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Author name code: ruzmaikin
ADS astronomy entries on 2022-09-14
author:"Ruzmaikin, Alexander"
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Title: Clustering of Fast Coronal Mass Ejections during Solar Cycles
23 and 24 and Implications for CME-CME Interactions
Authors: Rodriguez Gomez, Jenny Marcela; Podlachikova, Tatiana;
Veronig, Astrid; Ruzmaikin, Alexander; Feynman, Joan; Petrukovich,
Anatoly
2021EGUGA..23.3990R Altcode:
Coronal Mass Ejections (CMEs) and their interplanetary counterparts
(ICMEs) are the major sources for strong space weather disturbances. We
present a study of statistical properties of fast CMEs (v≥1000
km/s) that occurred during solar cycles 23 and 24. We apply the Max
Spectrum and the declustering threshold time methods. The Max Spectrum
can detect the predominant clusters, and the declustering threshold
time method provides details on the typical clustering properties
and timescales. Our analysis shows that during the different phases
of solar cycles 23 and 24, fast CMEs preferentially occur as isolated
events and in clusters with, on average, two members. However, clusters
with more members appear, particularly during the maximum phases of
the solar cycles. During different solar cycle phases, the typical
declustering timescales of fast CMEs are τc =28-32 hrs, irrespective
of the very different occurrence frequencies of CMEs during a solar
minimum and maximum. These findings suggest that τc for extreme events
may reflect the characteristic energy build-up time for large flare and
CME-prolific active regions. Statistically associating the clustering
properties of fast CMEs with the disturbance storm time index at Earth
suggests that fast CMEs occurring in clusters tend to produce larger
geomagnetic storms than isolated fast CMEs. Our results highlight the
importance of CME-CME interaction and their impact on Space Weather.
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Title: Clustering of Fast Coronal Mass Ejections during Solar Cycles
23 and 24 and the Implications for CME-CME Interactions
Authors: Rodríguez Gómez, Jenny M.; Podladchikova, Tatiana; Veronig,
Astrid; Ruzmaikin, Alexander; Feynman, Joan; Petrukovich, Anatoly
2020ApJ...899...47R Altcode: 2020arXiv200610404R
We study the clustering properties of fast coronal mass ejections
(CMEs) that occurred during solar cycles 23 and 24. We apply two
methods: the Max Spectrum method can detect the predominant clusters,
and the declustering threshold time method provides details on the
typical clustering properties and timescales. Our analysis shows that
during the different phases of solar cycles 23 and 24, CMEs with speeds
≥1000 km s<SUP>-1</SUP> preferentially occur as isolated events and
in clusters with, on average, two members. However, clusters with more
members appear, particularly during the maximum phases of the solar
cycles. Over the total period and in the maximum phases of solar cycles
23 and 24, about 50% are isolated events, 18% (12%) occur in clusters
with two (three) members, and another 20% in larger clusters ≥4,
whereas in a solar minimum, fast CMEs tend to occur more frequently as
isolated events (62%). During different solar cycle phases, the typical
declustering timescales of fast CMEs are τ<SUB>c</SUB> = 28-32 hr,
irrespective of the very different occurrence frequencies of CMEs during
a solar minimum and maximum. These findings suggest that τ<SUB>c</SUB>
for extreme events may reflect the characteristic energy build-up
time for large flare and CME-prolific active regions. Statistically
associating the clustering properties of fast CMEs with the disturbance
storm time index at Earth suggests that fast CMEs occurring in clusters
tend to produce larger geomagnetic storms than isolated fast CMEs. This
may be related to CME-CME interaction producing a more complex and
stronger interaction with Earth's magnetosphere.
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Title: Nonlinear mean-field dynamo and prediction of solar activity
Authors: Safiullin, N.; Kleeorin, N.; Porshnev, S.; Rogachevskii,
I.; Ruzmaikin, A.
2018JPlPh..84c7306S Altcode: 2017arXiv171207501S
We apply a nonlinear mean-field dynamo model which includes a
budget equation for the dynamics of Wolf numbers to predict solar
activity. This dynamo model takes into account the algebraic and dynamic
nonlinearities of the α effect, where the equation for the dynamic
nonlinearity is derived from the conservation law for the magnetic
helicity. The budget equation for the evolution of the Wolf number
is based on a formation mechanism of sunspots related to the negative
effective magnetic pressure instability. This instability redistributes
the magnetic flux produced by the mean-field dynamo. To predict solar
activity on the time scale of one month we use a method based on a
combination of the numerical solution of the nonlinear mean-field dynamo
equations and the artificial neural network. A comparison of the results
of the prediction of the solar activity with the observed Wolf numbers
demonstrates a good agreement between the forecast and observations.
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Title: Solar cycle variations in mesospheric carbon monoxide
Authors: Lee, Jae N.; Wu, Dong L.; Ruzmaikin, Alexander; Fontenla, Juan
2018JASTP.170...21L Altcode:
As an extension of Lee et al. (2013), solar cycle variation of carbon
monoxide (CO) is analyzed with MLS observation, which covers more
than thirteen years (2004-2017) including maximum of solar cycle
24. Being produced primarily by the carbon dioxide (CO<SUB>2</SUB>)
photolysis in the lower thermosphere, the variations of the mesospheric
CO concentration are largely driven by the solar cycle modulated
ultraviolet (UV) variation. This solar signal extends down to the
lower altitudes by the dynamical descent in the winter polar vortex,
showing a time lag that is consistent with the average descent
velocity. To characterize a global distribution of the solar impact,
MLS CO is correlated with the SORCE measured total solar irradiance
(TSI) and UV. As high as 0.8 in most of the polar mesosphere, the
linear correlation coefficients between CO and UV/TSI are more
robust than those found in the previous work. The photochemical
contribution explains most (68%) of the total variance of CO while the
dynamical contribution accounts for 21% of the total variance at upper
mesosphere. The photochemistry driven CO anomaly signal is extended
in the tropics by vertical mixing. The solar cycle signal in CO is
further examined with the Whole Atmosphere Community Climate Model
(WACCM) 3.5 simulation by implementing two different modeled Spectral
Solar Irradiances (SSIs): SRPM 2012 and NRLSSI. The model simulations
underestimate the mean CO amount and solar cycle variations of CO, by a
factor of 3, compared to those obtained from MLS observation. Different
inputs of the solar spectrum have small impacts on CO variation.
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Title: Solar Cycle Variations as Observed by MLS Carbon Monoxide
Authors: Lee, J. N.; Wu, D. L.; Ruzmaikin, A.; Fontenla, J. M.
2017AGUFMSH43B2813L Altcode:
More than thirteen years (2004-2017) of carbon monoxide (CO)
measurements from the Aura Microwave Limb Sounder (MLS) are analyzed
to better understand impacts of solar cycle 24. The upper mesospheric
CO, produced primarily by the carbon dioxide (CO2) photolysis in the
lower thermosphere, is sensitive to solar irradiance variability. We
find that interannual variations of the mesospheric CO concentration
are largely driven by the solar-cycle modulated ultraviolet (UV)
variation in most of the UV wavelengths (120 to 280 nm) in high
latitude regions. Despite different mean CO abundances in the SH and
NH winters, their solar-cycle dependence appears to be symmetric with
respect to the winter pole. This solar signal extends down to the
lower altitudes by the dynamical descent in the polar vortex, showing
a time lag that is consistent with the average descent velocity. To
characterize a global distribution of the solar influence, Aura MLS CO
is correlated with the Solar Radiation and Climate Experiment (SORCE)
Total Irradiance Monitor (TIM) measured total solar irradiance (TSI)
and with the SORCE Solar-Stellar Irradiance Comparison Experiment
(SOLSTICE) measured UV. As high as 0.8 in most of the polar mesosphere,
the linear correlation coefficients between CO and UV/TSI are more
robust than those found in the previous work, with the extended
analysis period. Different from the result shown in Lee et al. (2013),
the downward propagation of the solar signals is similar in both NH
and SH high latitudes. Effects of solar forcing on mesospheric CO
extend far beyond the polar region. CO is a good tracer to show that
the solar induced CO anomaly seems to follow the global meridional
residual circulation and hemispheric transition from pole to pole in
every six months. WACCM simulation experiment with two different solar
spectral irradiance models, SRPM (Solar Radiation Physical Modeling)
2012 and NRLSSI (Naval Research Laboratory Spectral Solar Irradiance),
shows that the modeled CO variability in the mesosphere over a solar
cycle is weaker by a factor of three than that shown from MLS CO
observation. Two different model inputs for the solar spectrum have
small impacts, not enough to explain the large discrepancy with the
observation. Lacks of strength and variability of the mean meridional
circulation in the model, instead of the model photochemistry, most
likely cause the weak CO variability in the mesosphere.
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Title: The Earth's Climate at Minima of the Centennial Gleissberg
Cycles
Authors: Ruzmaikin, A.; Feynman, J.
2016AGUFMSH43D2593R Altcode:
The recent extended and deep minimum of solar variability and the
extended minima in the 19th and 20th centuries (1810-1830 and 1900-1920)
are consistent with minima of the Centennial Gleissberg Cycle (CGC),
a 90-100 year variation of the amplitude of the 11-year sunspot
cycle observed on the Sun, solar wind, and at the Earth. The CGC has
been identified in the Total Solar Irradiance reconstructed for over
three centuries. The Earth's climate response to the prolonged low
solar irradiance involves heat transfer to the deep ocean with a time
lag longer than a decade. The CGC minima, sometimes coincidently in
combination with volcanic forcing, are associated with severe weather
extremes. Thus the 19th century CGC minimum, coexisted with volcanic
eruptions, led to especially cold conditions in United States, Canada
and Western Europe ("a year without summer"). Using the reconstructed
solar forcing and modeled and reconstructed Earth's temperature data
we identify the timing and spatial pattern of the Earth's climate
response that allows distinguishing the solar forcing from other
climate forcings.
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Title: The Earth's climate at minima of Centennial Gleissberg Cycles
Authors: Ruzmaikin, Alexander; Feynman, Joan
2015AdSpR..56.1590R Altcode:
The recent extended, deep minimum of solar variability and the extended
minima in the 19th and 20th centuries (1810-1830 and 1900-1920)
are consistent with minima of the Centennial Gleissberg Cycle (CGC),
a 90-100 year variation of the amplitude of the 11-year sunspot cycle
observed on the Sun and at the Earth. The Earth's climate response to
these prolonged low solar radiation inputs involves heat transfer to the
deep ocean causing a time lag longer than a decade. The spatial pattern
of the climate response, which allows distinguishing the CGC forcing
from other climate forcings, is dominated by the Pacific North American
pattern (PNA). The CGC minima, sometimes coincidently in combination
with volcanic forcing, are associated with severe weather extremes. Thus
the 19th century CGC minimum, coexisted with volcanic eruptions, led to
especially cold conditions in United States, Canada and Western Europe.
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Title: Clustering of atmospheric data by the deterministic annealing
Authors: Ruzmaikin, Alexander; Guillaume, Alexandre
2014JASTP.120..121R Altcode:
The Deterministic Annealing (DA) clustering method, which determines
the cluster centers, their sizes, and probability with which data
are associated with each cluster, is tested using artificial data and
applied to atmospheric satellite data. It is also shown how the method
can be advantageously used to characterize data outliers. The method
is based on the optimization of a cost function that depends both
on the averaged distance of data points to cluster centers and the
Shannon entropy of the data. The cost function uses two independent
parameters in a close analog to the Gibbs' thermodynamics (with the
averaged distance similar to the internal energy) allowing a sufficient
control of the formation of new clusters as “phase transitions”
by changing the clustering parameter similar to the thermodynamical
temperature. The satellite data used are a temperature-water vapor
data set and the positions of deep convective clouds obtained from
the measurements of the Atmospheric InfraRed Sounder (AIRS) on the
Aqua satellite. The clustering of these data is demonstrated for the
2D case (at fixed pressure level) and for the 3D case at multiple
pressure levels indicating potential applications to investigation of
distributions of atmospheric profiles.
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Title: The Centennial Gleissberg Cycle and its association with
extended minima
Authors: Feynman, J.; Ruzmaikin, A.
2014JGRA..119.6027F Altcode:
The recent extended minimum of solar and geomagnetic variability
(XSM) mirrors the XSMs in the nineteenth and twentieth centuries:
1810-1830 and 1900-1910. Such extended minima also were evident in
aurorae reported from 450 A.D. to 1450 A.D. This paper argues that these
minima are consistent with minima of the Centennial Gleissberg Cycles
(CGCs), a 90-100 year variation observed on the Sun, in the solar
wind, at the Earth, and throughout the heliosphere. The occurrence
of the recent XSM is consistent with the existence of the CGC as
a quasiperiodic variation of the solar dynamo. Evidence of CGCs
is provided by the multicentury sunspot record, by the almost 150
year record of indexes of geomagnetic activity (1868 to present),
by 1000 years of observations of aurorae (from 450 to 1450 A.D.) and
millennial records of radionuclides in ice cores. The aa index of
geomagnetic activity carries information about the two components
of the solar magnetic field (toroidal and poloidal), one driven by
flares and coronal mass ejections (related to the toroidal field) and
the other driven by corotating interaction regions in the solar wind
(related to the poloidal field). These two components systematically
vary in their intensity and relative phase giving us information
about centennial changes of the sources of solar dynamo during the
recent CGC over the last century. The dipole and quadrupole modes of
the solar magnetic field changed in relative amplitude and phase; the
quadrupole mode became more important as the XSM was approached. Some
implications for the solar dynamo theory are discussed.
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Title: Patterns of carbon monoxide in the middle atmosphere and
effects of solar variability
Authors: Ruzmaikin, Alexander; Lee, Jae N.; Wu, Dong L.
2014AdSpR..54..320R Altcode:
We determine the spatial-time patterns of zonally averaged carbon
monoxide (CO) in the middle atmosphere by applying Principle Component
Analysis to the CO data obtained from the Microwave Limb Sounder (MLS)
measurements on the Aura satellite in 2004-2012. The first two principal
components characterize more than 90% of the CO variability. Both
principal components are localized in the low thermosphere near the
mesopause. The first principal component is asymmetric relative to the
poles. It has opposite signs in the Northern and Southern Hemisphere
at mid to high latitudes and strongly oscillates with an annual
periodicity. The second principal component has the same sign in both
hemispheres and oscillates mainly with a semi-annual frequency. Both
principal components are modulated by the 11-year solar cycle and
display short-term variations. To test possible correlations of these
variations with the short term solar ultraviolet (UV) variability we
use the simultaneous measurements of the UV solar radiance from the
Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) on the Solar
Radiation and Climate Experiment (SORCE) satellite to investigate
the correlation between CO in the middle atmosphere and solar UV in
2004-2012. Using a wavelet coherence technique a weak, intermittent
27-day signal is detected in high-frequency parts of the CO principal
components.
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Title: The Centennial Gleissberg Cycle: Origin and Forcing of Climate
Authors: Ruzmaikin, A.; Feynman, J.
2014ASPC..484..189R Altcode:
We discuss the origin of the Centennial Gleissberg Cycle (CGC) of
solar activity and its forcing of the Earth's climate. The solar
dynamo models, which explain the process of generating the 11-year
cycle via the differential rotation and mean helicity, need to be
extended to a non-linear regime that includes feedback processes. The
strongest feedback on the centennial time scale is expected from the
mean helicity. We advocate that the best way to see the response
of the Earth's climate to the CGC forcing is to investigate the
climate patterns, not the global temperature. There is anecdotal
evidence of extreme low temperatures in the climate patterns at the
GCC minima. Numerical modeling indicates a patterned response of the
ocean to the CGC forcing.
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Title: Minima of the Centennial Gleissberg Cycle and the Heliospheric
Boundary
Authors: Feynman, J.; Ruzmaikin, A.
2014ASPC..484...36F Altcode:
The Centennial Gleissberg Cycle (CGC) is a 90-100 year variation
observed on the Sun, in the solar wind, at Earth and throughout the
Heliosphere. The CGC is expressed as a systematic variation of the
amplitude of the 11-year sunspot cycle. The reality of the CGC was a
matter of some debate, but the very weak solar wind that occurred during
the recent transition from solar cycle 23 to 24 followed by a low cycle
24 maximum sunspot number, strongly supports the concept. In this paper
we demonstrate the strong similarities among the CGC minima observed
at the beginnings of the 18th, 19th, 20th, and 21st century. These
similarities support the notion that we are now experiencing a typical
CGC minimum solar wind that is significantly different from the solar
wind observed earlier in the space age. We suggest that the current CGC
minimum may be implicated in producing some aspects of the unexpected
observations at the heliosphere boundary reported at this conference.
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Title: Solar Variability on Centennial Time Scale
Authors: Ruzmaikin, Alexander
2014cosp...40E2819R Altcode:
The recent extended minimum of solar variability mirrors the minima
in the 20th, 19th, 18th and earlier centuries. These minima fit
into the Centennial Gleissberg Cycle (CGC), a 90-100 year variation
observed on the Sun, in the solar wind, at the Earth and throughout
the Heliosphere. Evidence of the CGC is provided by the multi-century
sunspot record, and by longer records of the geomagnetic activity and
radio nuclear isotopes. To explain the centennial solar variability
in the framework of the mean-field solar dynamo the back action of
the mean magnetic field on the sources of its generation must be taken
into account. There is observational evidence of extreme low Earth’s
temperatures at the GCC minima indicating the CGC variability influence
on climate. A good way to see the response of the Earth's climate to
the CGC forcing is to investigate the climate patterns.
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Title: Interannual variations of MLS carbon monoxide induced by
solar cycle
Authors: Lee, Jae N.; Wu, Dong L.; Ruzmaikin, Alexander
2013JASTP.102...99L Altcode:
More than eight years (2004-2012) of carbon monoxide (CO) measurements
from the Aura Microwave Limb Sounder (MLS) are analyzed. The mesospheric
CO, largely produced by the carbon dioxide (CO<SUB>2</SUB>) photolysis
in the lower thermosphere, is sensitive to the solar irradiance
variability. The long-term variation of observed mesospheric MLS CO
concentrations at high latitudes is likely driven by the solar-cycle
modulated UV forcing. Despite of different CO abundances in the southern
and northern hemispheric winter, the solar-cycle dependence appears
to be similar. This solar signal is further carried down to the lower
altitudes by the dynamical descent in the winter polar vortex. Aura MLS
CO is compared with the Solar Radiation and Climate Experiment (SORCE)
total solar irradiance (TSI) and also with the spectral irradiance in
the far ultraviolet (FUV) region from the SORCE Solar-Stellar Irradiance
Comparison Experiment (SOLSTICE). Significant positive correlation
(up to 0.6) is found between CO and FUV/TSI in a large part of the
upper atmosphere. The distribution of this positive correlation in the
mesosphere is consistent with the expectation of CO changes induced
by the solar irradiance variations.
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Title: Decadal variability of tropical Pacific temperature in relation
to solar cycles
Authors: Ruzmaikin, Alexander; Aumann, Hartmut H.
2012AdSpR..49..572R Altcode:
We use the 8-year long satellite temperature data (2002-2010) from
Atmospheric InfraRed Sounder (AIRS) and Atmospheric Microwave Sounding
Unit (AMSU) on the Aqua satellite to identify temperature trends in
the troposphere and low stratosphere over the Niño 3.4 region of the
Tropical Pacific Ocean in the most recent 11-year solar cycle. Employing
more extended sea surface temperature (SST) data for five solar cycles
(1950-2009) in this region we show that the satellite trends reflect
a typical decrease of the sea surface temperature (SST) in the Niño
3.4 region in the declining phase of the solar cycle. The magnitude
of the SST decrease depends on the solar cycle and ranges between 0.07
K/yr and 0.27 K/yr for the last five solar cycles.
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Title: Implications of the Deep Cycle 23/24 Minimum for our
Understanding of the Solar Dynamo
Authors: Feynman, J.; Ruzmaikin, A.
2011AGUFMSH24B..03F Altcode:
When the cycle 23/24 minimum is considered in the light of the existing
record of 1,500 years of solar output proxies, it can be understood
as a typical minimum of a periodic modulation of the amplitude of
the 11-year solar cycle, which we call the Centennial Gleissberg Cycle
(CGC). This 90-100 year amplitude variation has been well established by
earlier studies (Gleissberg, 1965, Siscoe, 1980, Silverman and Feynman,
1980, Sonnett, 1982) and is present at least 80% of the time since 450
AD. It consists of a series of about nine or ten 11-year cycles with
amplitudes that gradually rise and then fall (Feynman and Fougere,
1988). Previous well-established deep minima took place about 1710,
1810 (Dalton Minimum) and 1910. Because of this record a minimum about
2010 was not unexpected (e.g. Silverman, 1992). The CGC was also seen
in auroral observations from 450 AD to 1450 AD. It thus appears that
the magnetic field generated by the solar dynamo has a quasi-periodic
variation of about 100 years, the cause of which demands future
study. In this talk we will review the evidence that the peculiar
behavior noticed during 23/24 minimum was a CGC minimum. We will
describe the CGC and develop criteria to distinguish it from Grand
Minima such as the Maunder Minimum. When these criteria are applied
to the observations, the CGC hypothesis is clearly favored. We will
discuss possible models of non-linear dynamos that can explain the
origin of the CGC.
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Title: The Sun's Strange Behavior: Maunder Minimum or Gleissberg
Cycle?
Authors: Feynman, J.; Ruzmaikin, A.
2011SoPh..272..351F Altcode:
During the last few years the Sun and solar wind have shown a behavior
that was so unexpected that the phenomena was described as "the
strange solar minimum". It has been speculated that the 23/24 solar
cycle minimum may have indicated the onset of a Maunder-Minimum-type
Grand Minimum. Here we review what is known from 1500 years of proxy
data about Maunder-type Grand Minima and the minima of the cyclic
Centennial Gleissberg variations. We generate criteria that distinguish
between the two types of event. Applying these criteria to the observed
solar terrestrial data we conclude that the unexpected behavior began
well before the solar cycle 23/24 minimum. The data do not support the
Maunder Minimum conjecture. However, the behavior can be understood as
a minimum of the Centennial Gleissberg Cycle that previously minimized
in the beginning of the 20th century. We conclude that the Centennial
Gleissberg Cycle is a persistent variation that has been present 80%
of the time during the last 1500 years and should be explained by
solar dynamo theory.
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Title: Distribution and clustering of fast coronal mass ejections
Authors: Ruzmaikin, A.; Feynman, J.; Stoev, S. A.
2011JGRA..116.4220R Altcode:
The purpose of this paper is to investigate the statistical properties
of high-speed coronal mass ejections (fast CMEs), which play a major
role in Space Weather. We study the cumulative distribution of the
initial CME speeds applying a new, advanced statistical method based
on the scaling properties of averages of maximal speeds selected in
time intervals of fixed sizes. This method allows us for the first
time to obtain a systematic statistical description of the fast CME
speeds. Using this method, we identify a self-similar (power law)
high-speed portion of the spectrum of the speed maxima in the range
of speeds from about 700 km/s to 2000 km/s. This self-similar range
of the speed distribution provides a meaningful definition of “the
fast” CMEs and indicates that these CMEs are produced by a process
that is the same across the range of scales. The investigation of
the temporal behavior of the fast CME events indicates that the
time intervals between fast CMEs are not independent, i.e., fast
CMEs arrive in clusters. We characterize the fast CMEs clustering
by the exponent $\theta$ called the extremal index, which is the
inverse of the averaged number of CMEs per cluster. An independent
correlation analysis of the tail of the CME distribution confirms
and further quantifies the temporal dependence among the fast CME
events. To illustrate the predictive capabilities of the method, we
identify clusters in the time series of CMEs with speeds greater than
1000 km/s and calculate their statistical characteristics such as the
size and duration of the clusters. The method used in this paper can
be applied to many other extreme geophysical events.
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Title: Distribution of extreme solar energetic proton fluxes
Authors: Ruzmaikin, Alexander; Feynman, Joan; Jun, Insoo
2011JASTP..73..300R Altcode:
The knowledge of the high intensity tails of probability distributions
that determine the rate of occurrence of extreme events of solar
energetic particles is a critical element in the evaluation of hazards
for human and robotic space missions. Here instead of the standard
approach based on fitting a selected distribution function to the
observed data we investigate a different approach, which is based on a
study of the scaling properties of the maximum particle flux in time
intervals of increasing length. To find the tail of the probability
distributions we apply the “Max-Spectrum” method (Stoev, S.A.,
Michailidis, G., 2006. On the estimation of the heavy-tail exponent in
time series using the Max-Spectrum. Technical Report 447, Department
of Statistics, University of Michigan) to 1973-1997 IMP-8 proton
data and the 1987-2008 GOES data, which cover a wide range of proton
energies. We find that both data sets indicate a power-law tail with
the power exponents close to 0.6 at least in the energy range 9-60
MeV. The underlying probability distribution is consistent with the
Fréchet type (power-law behavior) extreme value distribution. Since
the production of high fluxes of energetic particles is caused by fast
Coronal Mass Ejections (CMEs) this heavy-tailed distribution also
means that the Sun generates more fast CMEs than would be expected
from a Poissonian-type process.
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Title: Distribution and Clustering of Fast Coronal Mass Ejections
Authors: Feynman, J.; Ruzmaikin, A.; Stoev, S.
2010AGUFMSH43A1809F Altcode:
In many geophysical phenomena such as hurricanes, the solar energetic
particle events and the coronal mass ejections we discuss here, the
knowledge of the tails of the probability distribution functions is
critical to our understanding and forecasting of the most hazardous
extreme events. In addition, often the events appear to cluster making
†he statistical samplings based on independent events incorrect. The
probability distributions of extreme events are not Gaussian but are
characterized by extended high intensity tails. In practice, it has
become common to estimate the shape of the tail using an empirical
fit to a known distribution function, such as a log-normal. These
empirical estimates are often challenged because the validity of
the basic mathematics of statistics underlying them has not been
demonstrated. Recently new statistical techniques have been developed
that allow us to test the validity of our empirical methods. We apply
one of the new methods based on the use of scaling properties of the
data maxima to the distribution of speeds of coronal mass ejections
(CMEs). We show that the distribution function of the fast CME speeds
asymptotically follows the power-law extreme value distribution and
that the intervals between fast CMEs do not follow the exponential
distribution expected for independent random events but cluster in
time. This work was supported by the Jet Propulsion Laboratory of the
California Institute of Technology, under a contract with the National
Aeronautics and Space Administration.
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Title: The DynaMICCS perspective. A mission for a complete and
continuous view of the Sun dedicated to magnetism, space weather
and space climate
Authors: Turck-Chièze, S.; Lamy, P.; Carr, C.; Carton, P. H.;
Chevalier, A.; Dandouras, I.; Defise, J. M.; Dewitte, S.; Dudok de Wit,
T.; Halain, J. P.; Hasan, S.; Hochedez, J. F.; Horbury, T.; Levacher,
P.; Meissonier, M.; Murphy, N.; Rochus, P.; Ruzmaikin, A.; Schmutz,
W.; Thuillier, G.; Vivès, S.
2009ExA....23.1017T Altcode: 2008ExA...tmp...42T
The DynaMICCS mission is designed to probe and understand the dynamics
of crucial regions of the Sun that determine solar variability,
including the previously unexplored inner core, the radiative/convective
zone interface layers, the photosphere/chromosphere layers and the
low corona. The mission delivers data and knowledge that no other
known mission provides for understanding space weather and space
climate and for advancing stellar physics (internal dynamics)
and fundamental physics (neutrino properties, atomic physics,
gravitational moments...). The science objectives are achieved
using Doppler and magnetic measurements of the solar surface,
helioseismic and coronographic measurements, solar irradiance at
different wavelengths and in-situ measurements of plasma/energetic
particles/magnetic fields. The DynaMICCS payload uses an original
concept studied by Thalès Alenia Space in the framework of the
CNES call for formation flying missions: an external occultation of
the solar light is obtained by putting an occulter spacecraft 150 m
(or more) in front of a second spacecraft. The occulter spacecraft,
a LEO platform of the mini sat class, e.g. PROTEUS, type carries
the helioseismic and irradiance instruments and the formation flying
technologies. The latter spacecraft of the same type carries a visible
and infrared coronagraph for a unique observation of the solar corona
and instrumentation for the study of the solar wind and imagers. This
mission must guarantee long (one 11-year solar cycle) and continuous
observations (duty cycle > 94%) of signals that can be very weak
(the gravity mode detection supposes the measurement of velocity
smaller than 1 mm/s). This assumes no interruption in observation
and very stable thermal conditions. The preferred orbit therefore is
the L1 orbit, which fits these requirements very well and is also an
attractive environment for the spacecraft due to its low radiation and
low perturbation (solar pressure) environment. This mission is secured
by instrumental R and D activities during the present and coming
years. Some prototypes of different instruments are already built
(GOLFNG, SDM) and the performances will be checked before launch on
the ground or in space through planned missions of CNES and PROBA ESA
missions (PICARD, LYRA, maybe ASPIICS).
---------------------------------------------------------
Title: Quasi-periodic patterns coupling the Sun, solar wind and
the Earth
Authors: Ruzmaikin, Alexander; Cadavid, Ana Cristina; Lawrence, John
2008JASTP..70.2112R Altcode:
The spectrum of velocity and magnetic fields in the solar wind is
self-similar (power-law type) in the frequency range greater than
>1/day indicating well-mixed turbulence. But it loses self-similarity
for lower frequencies indicating the presence of large-scale patterns,
which are intermittently generated inside the Sun and propagate from the
Sun to the Earth. Here we discuss the spatia-temporal characteristics
and origin of the 1.3-year quasi-periodic pattern found inside the Sun
by helioseismic methods and detected in the solar wind. To identify
and characterize this pattern on the Sun we use time series of solar
magnetic Carrington maps generated at the Wilcox Solar Observatory
and independent component data analysis. This analysis shows the
latitudinal distribution of the pattern, its variable frequency and
intermittent appearance.
---------------------------------------------------------
Title: Frequency of severe storms and global warming
Authors: Aumann, Hartmut H.; Ruzmaikin, Alexander; Teixeira, Joao
2008GeoRL..3519805A Altcode:
We use five years of data from the Atmospheric Infrared Sounder (AIRS)
to develop a correlation between the frequency of Deep Convective Clouds
(DCC) and the zonal mean tropical surface temperature. AIRS data show
that the frequency of DCC in the tropical oceans is very temperature
sensitive, increasing 45% per 1 K increase of the zonal mean surface
temperature. The combination of the sensitivity of the DCC frequency to
temperature indicates that the frequency of DCC, and as a consequence
the frequency of severe storms, increases at the rate of 6%/decade with
the current +0.13 K/decade rate of global warming. This result is only
qualitatively consistent with state-of-the-art climate models, where the
frequency of the most intense rain events increases with global warming.
---------------------------------------------------------
Title: Rotational Quasi-Periodicities and the Sun - Heliosphere
Connection
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
2008SoPh..252..179L Altcode: 2008arXiv0803.3260L; 2008SoPh..tmp..138L
Mutual quasi-periodicities near the solar-rotation period appear in
time series based on the Earth's magnetic field, the interplanetary
magnetic field, and signed solar-magnetic fields. Dominant among these
is one at 27.03±0.02 days that has been highlighted by Neugebauer et
al. (J. Geophys. Res.105, 2315, 2000). Extension of their study in
time and to different data reveals decadal epochs during which the
≈ 27.0 days, or a ≈ 28.3 days, or other quasi-periods dominate
the signal. Space-time eigenvalue analyses of time series in 30 solar
latitude bands, based on synoptic maps of unsigned photospheric fields,
lead to two maximally independent modes that account for almost 30%
of the data variance. One mode spans 45° of latitude in the northern
hemisphere and the other one in the southern. The modes rotate
around the Sun rigidly, not differentially, suggesting connection
with the subsurface dynamo. Spectral analyses yield familiar dominant
quasi-periods 27.04±0.03 days in the North and at 28.24±0.03 days
in the South. These are replaced during cycle 23 by one at 26.45±0.03
days in the North. The modes show no tendency for preferred longitudes
separated by ≈ 180°.
---------------------------------------------------------
Title: Principal Components and Independent Component Analysis of
Solar and Space Data
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
2008SoPh..248..247C Altcode: 2007arXiv0709.3263C
Principal components analysis (PCA) and independent component analysis
(ICA) are used to identify global patterns in solar and space data. PCA
seeks orthogonal modes of the two-point correlation matrix constructed
from a data set. It permits the identification of structures that remain
coherent and correlated or that recur throughout a time series. ICA
seeks for maximally independent modes and takes into account all
order correlations of the data. We apply PCA to the interplanetary
magnetic field polarity near 1 AU and to the 3.25R<SUB>⊙</SUB>
source-surface fields in the solar corona. The rotations of the
two-sector structures of these systems vary together to high accuracy
during the active interval of solar cycle 23. We then use PCA and ICA
to hunt for preferred longitudes in northern hemisphere Carrington
maps of magnetic fields.
---------------------------------------------------------
Title: Search for Persistent Quasi-Periodicities in the Solar and
Interplanetary Magnetic Fields
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
2007AGUFMSH23A1165L Altcode:
Previous analysis of the radial component of the interplanetary magnetic
field from 1962 - 1998 has revealed a dominant frequency of 27.03 days
to 0.02 day accuracy (Neugebauer, et al., 2000). We have repeated and
extended this analysis with OMNI data from 1963 - 2007 obtained from the
Coordinated Heliospheric Observations (COHO) database. Over this longer
data string we find that the 27.03 day Lomb-Scargle periodogram peak
is reduced while two side peaks near 26.8 days and 27.6 days become
almost as strong. In the interval 1999-2007 there are two dominant
periods near 26.5 days and 27.2 days. As a solar counterpart to the
above analysis we have searched for persistent rotation periods near
27 days of global patterns of photospheric magnetic fields derived from
Wilcox Solar Observatory synoptic Carrington rotation maps. Techniques
applied include, principal components analysis, independent component
analysis, singular spectrum analysis, wavelet spectral analysis,
and complex demodulation. We find a variety of quasi- periodicities
between 26 and 29 days that remain coherent for 1 - 2 years. In the
southern solar hemisphere the strongest periodicity is at 28.2 days,
while in the northern hemisphere it is around 26.5 days. Neugebauer,
M., Smith, Smith, E.J., Ruzmaikin, A., Feynman, J., Vaughan, A.H. 2000,
J. Geophys. Res., 106, A5, 8363.
---------------------------------------------------------
Title: Sunspots, El Niño, and the levels of Lake Victoria, East
Africa
Authors: Stager, J. Curt; Ruzmaikin, Alexander; Conway, Declan;
Verburg, Piet; Mason, Peter J.
2007JGRD..11215106S Altcode:
An association of high sunspot numbers with rises in the level of Lake
Victoria, East Africa, has been the focus of many investigations and
vigorous debate during the last century. In this paper, we show that
peaks in the ~11-year sunspot cycle were accompanied by Victoria level
maxima throughout the 20th century, due to the occurrence of positive
rainfall anomalies ~1 year before solar maxima. Similar patterns also
occurred in at least five other East African lakes, which indicates
that these sunspot-rainfall relationships were broadly regional in
scale. Although irradiance fluctuations associated with the sunspot
cycle are weak, their effects on tropical rainfall could be amplified
through interactions with sea surface temperatures and atmospheric
circulation systems, including ENSO. If this Sun-rainfall relationship
persists in the future, then sunspot cycles can be used for long-term
prediction of precipitation anomalies and associated outbreaks of
insect-borne disease in much of East Africa. In that case, unusually
wet rainy seasons and Rift Valley Fever epidemics should occur a year
or so before the next solar maximum, which is expected to occur in
2011-2012 AD.
---------------------------------------------------------
Title: Impact of Solar Variability on the Earth's Climate Patterns
Authors: Ruzmaikin, A.
2007AGUSM.A52B..02R Altcode:
We discuss the effect of solar variability on the Earth climate
patterns. The climate patterns are naturally excited in the noisy
atmosphere-ocean dynamical system as deviations (anomalies) from a
global (mean) state. Some of the climate patterns couple the upper
and lower atmosphere and are affected by the ocean. An example of
this type of climate pattern is the Northern Annular Mode (NAM),
a climate anomaly with two basic states corresponding to higher
pressure at high latitudes with a band of lower pressure at lower
latitudes and the other way round (Thompson & Wallace, 1998;
Baldwin & Dunkerton, 1999). Two states of the NAM arise due to
the dynamical interaction of planetary waves and zonal mean wind
(Limpasuvan & Hartmann, 2001; Ruzmaikin et al., 2006). The NAM
accounts for 23% of atmospheric variability at sea level and about 50%
of the variability in the stratosphere. Solar variability influences
the NAM through the change of the UV flux in upper atmosphere. The
influence depends on the phase of the Quasi Biennial Oscillation and
time in the winter season (Ruzmaikin & Feynman, 2002). We discuss
a possible mechanism by which solar variability can affect the NAM and
the climate patterns in general (involving the Rossby-Palmer conjecture,
Palmer, 1999). In contrast to the standard linear evaluation of climate
sensitivity to an external forcing we outline a non-linear approach
to the forcing problem. In particular, we evaluate the distributions
of residence times spent in each state of the pattern and show
how these distributions depend on external forcing caused by the
anthropogenic and solar changes. References: Thompson, D. W. J. &
J. M. Wallace, Geophys. Res. Lett., 25, 1297, 1998; Baldwin, M. P. &
T. J. Dunkerton, J. Geophys. Res. 104, 30,937, 1999; Limpasuvan,
V., & D. Hartmann, J. Climate, 13, 4414, 2001; Ruzmaikin, A.,
J, Feynman, J. Geophys. Res., 107, D14, 10.1029/2001JD001239, 2002;
Ruzmaikin, A., J. K. Lawrence & A. C. Cadavid, J. Atmos. Space
Phys., 68, 1311, 2006; Palmer, T. N., Bull. Amer. Meteor. Soc., 79,
1412 1998.
---------------------------------------------------------
Title: Effect of solar variability on the Earth’s climate patterns
Authors: Ruzmaikin, Alexander
2007AdSpR..40.1146R Altcode:
We discuss effects of solar variability on the Earth's large-scale
climate patterns. These patterns are naturally excited as deviations
(anomalies) from the mean state of the Earth's atmosphere-ocean
system. We consider in detail an example of such a pattern, the North
Annular Mode (NAM), a climate anomaly with two states corresponding
to higher pressure at high latitudes with a band of lower pressure
at lower latitudes and the other way round. We discuss a mechanism
by which solar variability can influence this pattern and formulate
an updated general conjecture of how external influences on Earth's
dynamics can affect climate patterns.
---------------------------------------------------------
Title: The 27-day variations in stratospheric ozone and temperature:
New MLS data
Authors: Ruzmaikin, A.; Santee, M. L.; Schwartz, M. J.; Froidevaux,
L.; Pickett, H. M.
2007GeoRL..34.2819R Altcode:
We use new data obtained by the Microwave Limb Sounder (MLS) onboard
of Aura spacecraft to investigate variations in stratospheric ozone
and temperature concurrent with the 27-day variations of solar UV
irradiance, measured simultaneously by the Solar Radiation and Climate
Experiment (SORCE) during the declining phase of solar activity. Using
Empirical Mode Decomposition we determine the latitudinal and height
distributions of the 27-day modes for ozone and temperature and find
that these modes are enhanced in the lower tropical stratosphere,
and at high latitudes in winter.
---------------------------------------------------------
Title: Statistics of solar energetic particle events: Fluences,
durations, and time intervals
Authors: Jun, I.; Swimm, R. T.; Ruzmaikin, A.; Feynman, J.; Tylka,
A. J.; Dietrich, W. F.
2007AdSpR..40..304J Altcode:
The high-energy solar proton data obtained from instruments onboard the
IMP-8 spacecraft are used to investigate statistical distributions
of event fluences, event durations, and time intervals between
adjacent events. The results show that: (1) the event fluences can be
approximately fit to a log-normal distribution and (2) the distributions
of event durations and time intervals between the events can be
represented by Poisson distributions. A virtual data set was generated
using these distributions to extend the Solar Probe method [Feynman, J.,
Tylka, A.J., Reames, D.B., Gabriel, S.B. Near-sun energetic particle
environment of Solar Probe-Phase1 final report, JPL Report, 2000] of
obtaining the mission-integrated fluences to longer missions. By using
the virtual data set generated in this study, we are able to obtain the
smooth distribution of mission fluences for missions of any duration,
which is not possible when only the available data sets was used.
---------------------------------------------------------
Title: Quasi-Periodicities, Magnetic Clusters and Solar Activity
Authors: Cadavid, A. C.; Lawrence, J. K.; Sandor, C.; Ruzmaikin, A.
2006AGUFMSH21A0325C Altcode:
To investigate quasi-periodicities, 12 hour averages of the radial
component of the interplanetary magnetic field and the solar wind speed,
covering ~ 42 (1963-2005) years were analyzed. A Lomb periodogram for
data up to 1998 showed a dominant period of 27.03 days as fpund in
earlier results. Including cycle 23, a dominant period of 27.06 days
was identified. Analysis of the solar cycles independently showed a
dominant period of 27.03 days in solar cycle 20, but not in the other
cycles. To investigate the degree of persistency of a particular signal,
the technique of complex demodulation was applied since it permits
the determination of continuous changes in time of the amplitude and
frequency of the signal relative to the test signal. It was found that
a period of ~27.6 days gave an overall flat phase function in time,
while other periods < ~0.5 day shorter and longer, with comparable
but lesser amplitude, come and go. To investigate the solar sources
of these periods, the method of principal component analysis (PCA) was
applied to ~ 27 years (1976-2003) of synoptic maps obtained with the NSO
Kitt Peak Vaccum Telescope. Before the analysis, the original synoptic
maps were shifted relative to the previous maps using the period under
investigation. Using PCA the Empirical Orthogonal Functions (EOFs)
and Pricipal Components (PCs) were found for the set of synoptic maps
rescaled to the rotation rate 27.03 days in 1999-2003. The patterns
characterized by EOFs 1 and 2 are mostly axisymmetric and PCs 1 and
2 show solar cycle variability. EOF3 shows only one well-localized
pattern in the Southern Hemisphere which is markedly non-axisymmetric
and PC3 has peaks at times when fast CMEs occur.
---------------------------------------------------------
Title: The New JPL Interplanetary Solar High-Energy Particle
Environment Model
Authors: Jun, I.; Swimm, R. T.; Ruzmaikin, A.; Feynman, J.; Tylka,
A. J.; Dietrich, W. F.
2006AGUFMSH51A1468J Altcode:
The high-energy protons and heavy ions from solar energetic particle
(SEP) events present hazard to space systems: damage to science
instruments/electronics or to astronauts. A reliable estimate of
the high-energy particle environment is very important to assure the
mission success. Without it, system survivability is often ensured
by setting grossly over-conservative mission requirements, resulting
in high mission costs, weight and physically large systems. However,
at present our ability to reliably predict the space environments for
missions not shielded by planetary magnetic fields is surprisingly poor,
especially for missions not at 1 AU. The primary reasons for this are
that: (1) SEP events are infrequent and sporadic, (2) statistically
valid data exist only at 1 AU, and (3) radial dependence of SEP
fluxes and fluences is still to be determined. Our ultimate goal is
to develop an advanced model that can reliably provide statistical
estimates of mission- integrated fluences of SEP high-energy protons
and heavy ions for arbitrary trajectories, launches on arbitrary future
dates, and an improved radial dependence law. This will be achieved by
adopting an approach used in a preliminary Solar Probe mission study,
that is, by flying a spacecraft through the database (described below)
with an appropriate radial dependence law being applied at each time
step. Here we present the preliminary results for a high-energy "proton"
model. For the study, we use the data obtained from the instruments
onboard the IMP-8 spacecraft: Goddard's Low Energy Detector (LED)
and Medium Energy Detector (MED) and the University of Chicago's
Cosmic Ray Nuclear Composition (CRNC) telescope. The data set covers
the period between 1973, day 305, and 1997, day 319, at 1 AU. All the
data were averaged over 6- hour intervals and corrected for background
by subtracting non-SEP contributions (i.e., contributions from galactic
cosmic rays and spurious instrumental effects).
---------------------------------------------------------
Title: Quasi-periodicities and Empirical Modes of the Heliospheric
Magnetic Field
Authors: Smith, E. J.; Zhou, X.; Ruzmaikin, A.
2006AGUFMSH53B1506S Altcode:
Quasi-periodicities in solar phenomena including variations in
the heliospheric magnetic field have attracted attention in the
past. Recently, such a periodicity near 140- 150 days has been of
interest. In a recent analysis of solar cycle variations in the Sun's
open magnetic flux, we found a quasi-periodicity of approximately one
and one-half years in the radial component and the field magnitude
that persists during the last four sunspot cycles. Inspection of the
data revealed that this signal was variable in both amplitude and
period. Power spectra having proved marginally useful in revealing
the signal properties, we apply a new technique called Empirical Mode
Decomposition (Huang et al., 1998) that treats both the frequency and
amplitude as time-dependent. Application of this technique revealed
several quasi-periodic modes including the mode near 1 and 1/2
years and the mode near 140 days that was not evident by inspection
alone. The results of this analysis will be presented and the origin
of the several periodicities will be discussed. Reference: Huang,
N. E. Z. Shen, S. R. Long, M. C. Wu, H. H. Shih, Q. Zheng, N.-C. Yen,
C. C. Tung, and H. H. Liu, Proc. R. Soc. Lond., A 454, 903-995, 1998.
---------------------------------------------------------
Title: Effect of Solar Variability on Earth Climate Patterns.
Authors: Ruzmaikin, A.; Feynman, J.
2006AGUFMSH11A0357R Altcode:
We discuss the impact of solar variability on the patterns of Earth
climate variability. These climate patterns are naturally excited in the
noisy atmosphere-ocean dynamical system as deviations (anomalies) from
a global (mean) state. The patterns include North Atlantic Oscillation
(NAO) and related Northern Annular Mode (NAM), Southern Annular Mode
(SAM), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal
Oscillation (AMO). An example of a pattern influenced by variations
in solar UV irradiance is the NAM, a wintertime climate anomaly with
two states corresponding to higher pressure at high latitudes with
a band of lower pressure at lower latitudes and the other way round
(Thompson &Wallace, 1998). Two states of the NAM arise due to
the dynamical interaction of planetary waves and zonal mean wind
(Limpasuvan &Hartmann, 2001; Ruzmaikin et al., 2006). The NAM
accounts for 23% of atmospheric variability at sea level and about
50% of the variability in the stratosphere. Solar variability affects
the NAM and that the influence varies dependent on the phase of the
Quasi Biennial Oscillation and time in the winter season (Ruzmaikin
&Feynman, 2002). The temperature pattern (cold in Europe-warm
in Greenland) produced by the negative NAM was dominant during the
Maunder Minimum of solar activity (Ruzmaikin et al., 2004). We
discuss possible physical mechanisms by which solar variability
can influence the climate patterns. In particular, we address the
Rossby-Palmer hypothesis (Palmer, 1998) that external forcing (in our
case solar variability) may affect only the magnitude of the pattern
variability without changing its spatial structure. References:
Thompson, D. W. J. &J. M. Wallace, Geophys. Res. Lett., 25,
1297, 1998; Palmer, T. N., Bull. Amer. Meteor. Soc., 79, 1412 1998;
Baldwin, M. P. and T. J. Dunkerton, J. Geophys. Res. 104, 30,937, 1999;
Limpasuvan, V., &D. Hartmann, J. Climate, 13, 4414, 2001; Ruzmaikin,
A., J, Feynman, J. Geophys. Res., 107, D14, 10.1029/2001JD001239,
2002; Ruzmaikin, A., J, Feynman, Xun Jiang, D. C. Noone, A. M. Waple
&Y. L. Yung, Geophys. Res. Let., 31, L12201, 2004; Ruzmaikin,
A., J. K. Lawrence &A. C. Cadavid, J. Atmos. Space Phys., 68,
1311, 2006.
---------------------------------------------------------
Title: Stratospheric wave-mean flow interaction: Simple modeling
Authors: Ruzmaikin, Alexander; Cristina Cadavid, Ana; Lawrence, John K.
2006JASTP..68.1311R Altcode: 2006JATP...68.1311R
We show that the interaction between planetary waves and the
stratospheric zonal mean flow results in bi-modal (direct-reverse
flow) or unimodal state depending on wave number of the waves. First
we demonstrate this using a simple non-linear dynamic system of the
wave-flow interaction, which has two stable equilibrium states and one
unstable state (attractors) in its phase space. Then we compare this
model dynamics with the stratosphere dynamics using the same dynamical
variables and a similar parameter range in the National Centers for
Environmental Prediction (NCEP) Reanalysis data. This comparison
supports the tendency for the states of planetary wave zonal mean
flow in the upper stratosphere to be bi-modal for wave number 2 and
unimodal for wave number 1.
---------------------------------------------------------
Title: Persistent Peridicities in the Solar Wind and Photospheric
Magnetic Field Coherent Structures
Authors: Cadavid, Ana C.; Lawrence, J. K.; Ruzmaikin, A.
2006SPD....37.1106C Altcode: 2006BAAS...38..239C
To investigate persistent periodicities, 12-hour averages of the
radial component of the interplanetary magnetic field and the solar
wind speed, covering 42 years (1963-2005), were analyzed. A Lomb
periodogram for the data up to 1998 showed maximum spectral power at
a period of 27.03 days, as encountered previously by Neugebauer et
al. (2000). Including cycle 23 shifted the peak to 27.06 days. Analysis
of solar cycles 20 - 23 separately showed a dominant period of 27.03
days in solar cycle 20, but not in the other cycles.To investigate
the degree of persistency and phase coherence of a particular signal,
the technique of complex demodulation was applied since it permits
the determination of continuous changes in time of the amplitude and
frequency of the signal relative to a test signal. It was found that
for a reference signal of 27.03 days, the phase was a flat function of
time during the intervals 1965-1972 and 1995-1997. The phase decreased
in time from 1972-1995 and increased after 1997. This implies that
for the intervals 1972-1995 and 1997-2005 other periodicities better
characterize the data. A period of 27.6 days gave an overall flat phase
function in time, while other periods < 0.5 day shorter and longer,
with comparable but lesser amplitude, come and go.To investigate the
solar sources of these periods, the methods of principal component
analysis (PCA) and independent component analysis (ICA) were applied
to 27 years (1976-2003) of synoptic maps obtained with the NSO Kitt
Peak Vacuum Telescope. Before the analysis, the original synoptic
maps were shifted relative to the previous maps using the particular
period under investigation. PCA and ICA identified 3 modes for the
27.03 reference period and 2 modes for the 27.6 period that showed
clusters of magnetic activity at preferred longitudes.
---------------------------------------------------------
Title: Statistics of solar energetic particle events: fluences,
durations, and time intervals
Authors: Swimm, R.; Jun, I.; Ruzmaikin, A.; Feynman, J.; Tylka, A. J.;
Dietrich, W. F.
2006cosp...36..664S Altcode: 2006cosp.meet..664S
The high-energy protons and heavy ions from solar energetic particle SEP
events present hazard to space systems damage to science instruments
electronics or to astronauts A reliable estimate of the high-energy
particle environment is very important to assure the mission success
Without it system survivability is often ensured by setting grossly
over-conservative mission requirements resulting in high mission costs
weight and physically large systems However at present our ability to
reliably predict the space environments for missions not shielded by
planetary magnetic fields is surprisingly poor especially for missions
not at 1 AU The primary reasons for this are that 1 SEP events are
infrequent and sporadic 2 statistically valid data exist only at 1
AU and 3 radial dependence of SEP fluxes and fluences is still to be
determined Our ultimate goal is to develop an advanced model that can
reliably provide statistical estimates of mission-integrated fluences
of SEP high-energy protons and heavy ions for arbitrary trajectories
launches on arbitrary future dates and an improved radial dependence law
This will be achieved by adopting an approach used in a preliminary
Solar Probe mission study that is by flying a spacecraft through
the database described below with an appropriate radial dependence
law being applied at each time step While we are still progressing
towards the goal we present here the first results of our study on
statistical distributions of event fluences of event durations and of
time intervals between adjacent events For
---------------------------------------------------------
Title: Does the Nile reflect solar variability?
Authors: Ruzmaikin, Alexander; Feynman, Joan; Yung, Yuk
2006IAUS..233..511R Altcode:
Historical records of the Nile water level provide a unique opportunity
to investigate the possibility that solar variability influences
the Earth's climate. Particularly important are the annual records
of the water level, which are uninterrupted for the years 622-1470
A.D. These records are non-stationary, so that standard spectral
analyses cannot adequately characterize them. Here the Empirical Mode
Decomposition technique, which is designed to deal with non-stationary,
nonlinear time series, becomes useful. It allows the identification
of two characteristic time scales in the water level data that can be
linked to solar variability: the 88 year period and a time scale of
about 200 years. These time scales are also present in the concurrent
aurora data. Auroras are driven by coronal mass ejections and the
rate of auroras is an excellent proxy for solar variabiliy. Analysis
of auroral data contemporaneous with the Nile data shows peaks at
88 years and about 200 years. This suggests a physical link between
solar variability and the low-frequency variations of the Nile water
level. The link involves the influence of solar variability on the
North Annual Mode of atmospheric variability and its North Atlantic
and Indian Oceans patterns that affect rainfall over Eastren Equatorial
Africa where the Nile originates.
---------------------------------------------------------
Title: The radial and longitudinal dependence of SEP intensities
and fluences
Authors: Li, G.; Zank, G.; Verkhoglyadova, O.; Ruzmaikin, A.; Feynman,
J.; Jun, I.
2006cosp...36.3428L Altcode: 2006cosp.meet.3428L
Solar Energetic Particles SEPs are an important hazard in the context
of space weather These particles bombard spacecraft and can cause
instruments onboard to malfunction At sufficiently high energies and
dosages they can also be extremely harmful to biological materials
human bodies and are therefore one of the major safety concerns for
the future manned spacecraft program We now know that these particles
are associated with Coronal Mass Ejection CMEs driven shocks As
a CME-driven shock propagates outward particles are injected and
accelerated at the shock front via a first order Fermi mechanism aka
diffusive shock acceleration After being accelerated the particles
convect with the shock diffuse both upstream and downstream of the
shock and many eventually escape the shock complex after reaching far
upstream downstream In this work we present a model calculation of the
SEP time intensity profile The model is based on a 2D-ZEUS MHD code
which is used to simulate the solar wind The shock is modeled using
a shell model where particle convection and diffusion are followed
numerically When particles reach some distance ahead of the shock they
are can escape from the shock Their subsequent motion is followed using
a Monte-Carlo approach This sophisticated model allows us to obtain a
time intensity profile and instantaneous particle spectra at various
locations We will discuss the radial and longitudinal dependence of
both the intensities and fluences
---------------------------------------------------------
Title: Causes of extremely fast CMEs
Authors: Feynman, Joan; Ruzmaikin, Alexander
2006IAUS..233..343F Altcode:
We study CMEs observed by LASCO to have plane of the sky velocities
exceeding 1500 km/sec. We find that these extremely fast CMEs
are typically associated with flares accompanied by erupting
prominences. Our results are consistent with a single CME initiation
process that consists of three stages. The initial stage is brought
about by the emergence of new magnetic flux, which interacts with the
pre-existing magnetic configuration and results in a slow rise of the
magnetic structure. The second stage is a fast reconnection phase with
flaring, filament eruption and a sudden increase of the rise velocity of
the magnetic structure (CME). The third stage consists of propagation
in the corona. We discuss the sources of these CMEs and the need for
improved understanding of the first and third stages.
---------------------------------------------------------
Title: Coherent Structures vs Independent Modes of the Axisymmetric
Magnetic Field Fluctuations
Authors: Cadavid, A. C.; Lawrence, J. K.; McDonald, D. P.; Ruzmaikin,
A.
2005ASPC..346...91C Altcode:
Quasi periodicities on scales of 1 to 2.5 years have been observed in
solar, interplanetary and geomagnetic time series. The relation of
these signals to 1 and 1.3 yr fluctuations in the solar interior,
suggest the presence of structures or characteristic modes in
the magnetic field, generated by the dynamo, that extend into the
heliosphere. We have applied the methods of principal component
analysis (PCA) and independent component analysis (ICA) to search
for the coherent structures (PCA) and independent global modes (ICA)
of the axisymmetric solar magnetic field. While PCA is effective in
identifying the coherent modes that describe the 22 yr solar cycle,
ICA uncovers the independent global modes the with characteristic 1 to
2.5 yr quasi periods observed in heliospheric and helioseismic time
series. Five modes capture the salient properties of the data. Two
modes describe the polar and high latitude fields, and present 1-1.5
yr quasi periodicities. The other three modes correspond to low and
mid-latitude phenomena and show both 1.3 yr and 1.7 yr variations.
---------------------------------------------------------
Title: The Radial Dependence of Solar Energetic Particle Fluxes
Authors: Ruzmaikin, Alexander; Li, Gang; Zank, Gary; Feynman, Joan;
Jun, Insoo
2005ESASP.592..441R Altcode: 2005soho...16E..77R; 2005ESASP.592E..77R
No abstract at ADS
---------------------------------------------------------
Title: Quasi periodicities in the Fluctuations of the Axisymmetric
Solar Magnetic Field from Independent Component Analysis
Authors: McDonald, D. P.; Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin,
A.
2005AGUSMSP43B..05M Altcode:
Observed solar, interplanetary and geomagnetic time series contain quasi
periodicities on the order of 1 to 2.5 years. The further discovery
of 1.3 year fluctuations in helioseismic observations suggests that
a variety of signals may be related to the underlying dynamo in the
Sun. We have applied the methods of principal component analysis (PCA)
and independent component analysis (ICA) to search for the coherent
structures (PCA) and independent global modes (ICA) of the axisymmetric
solar magnetic field. While PCA was shown to be effective in identifying
the coherent modes that describe the 22 yr solar cycle, ICA uncovers the
independent global modes with characteristic 1 to 2.5 yr quasi periods
observed in heliospheric and helioseismic time series. We found that
five modes effectively describe the data in both spatial and temporal
domains. Two modes describe the polar and high latitude fields,
and present 1-1.5 year quasi periodicities. The other three modes
correspond to low and mid-latitude phenomena and show both 1.3 year
and 1.7 year variations. By comparing the characteristic timescales,
dates of occurrence and heliocentric latitudes of these modes, we
connect them to their manifestations in heliospheric time series.
---------------------------------------------------------
Title: Coherent Structures and Rotation Rates in Coronal Activity,
from Principal Component Analysis
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
2005AGUSMSP21B..07C Altcode:
Principal component analysis (PCA) offers a way to extract those
structures that remain spatially coherent throughout a time series. We
apply this method to a ~ 28 year time series of Wilcox Solar Observatory
Carrington rotation maps (CR) of the 3.25 R coronal source surface field
obtained via a potential field extrapolation. We find that over 99%
of the variance is contained in the first eight modes. Mode 1, carrying
81.5% of the variance, and modes 2 and 3 containing 13% of the variance,
have "dipole" structures. Modes 4-8, with a "quadruple" structure,
contain 4.5% of the variance. The principal components (PCs) give the
time dependence of the modes. We combine the PCs of modes 2 and 3 to
get the amplitude and phase of a structure that behaves essentially as
a dipole in the equatorial plane. During activity minima the structure
is relatively weak and rotates at the 27.275 day Carrington rate. During
the active periods of cycles 21 and 22 the amplitude is large and highly
intermittent, and the dipole rotates more rapidly than the Carrington
rate with a synodic period of 26.6 days. During cycle 23, however, the
dipole moves backward in Carrington longitude with a synodic period
of 27.8 days. The average of these is ~ 27.0 days, though this is
actually realized only sporadically. The phase changes that occur at
shorter time scales and that coincide with intermittent changes in the
dipole amplitude seem to represent essentially random effects of the
passage of the magnetic field through the convection zone. While the
lower modes tend to lock the hemispheres together the higher modes
present separate Northern and Southern hemisphere quadrupole-type
patterns that drift in Carrington longitude similarly to the equatorial
dipole. Over some periods the drift in each hemisphere closely tracks
the other over a wide range of timescales. However, there are large,
decadal-scale excursions in which first one hemisphere leads in phase
by 3 or 4 rotations and then the other leads by a similar amount.
---------------------------------------------------------
Title: Independent Global Modes of Solar Magnetic Field Fluctuations
Authors: Cadavid, A. C.; Lawrence, J. K.; McDonald, D. P.; Ruzmaikin,
A.
2005SoPh..226..359C Altcode:
Observed solar, interplanetary and geomagnetic time series contain
quasi periodicities on scales of 1-2.5 years. The further discovery
of 1.3 year fluctuations in helioseismic observations suggests that
a variety of signals may be related to the underlying dynamo in the
Sun. We use independent component analysis to study the temporal and
spatial variations of a few statistically independent global modes of
the axisymmetric solar magnetic field over a period of 25 years. Five
modes capture the salient properties of the data. Two modes describe
the polar and high latitude fields, and present 1-1.5 year quasi
periodicities. The other three modes correspond to low and mid-latitude
phenomena and show both 1.3 and 1.7-year variations. By comparing
the characteristic time scales, dates of occurrence and heliocentric
latitudes of these modes, we connect them to their manifestations in
heliospheric time series.
---------------------------------------------------------
Title: Principal Component Analysis of the Solar Magnetic Field I:
The Axisymmetric Field at the Photosphere
Authors: Lawrence, John K.; Cristina Cadavid, Ana; Ruzmaikin, Alexander
2004SoPh..225....1L Altcode:
A principal component analysis, or proper orthogonal decomposition,
of the axisymmetric magnetic field at the photosphere is carried out to
find an optimal representation of the observed solar cycle. The 22-year
periodic field requires just two modes. NSO Kitt Peak synoptic maps for
Carrington rotations 1664-2007 were reduced by taking both the mean and
the median field over longitude to produce two sequences of functions
of sine latitude spanning 25.7 years. The lowest modes of each are
determined by the polar fields. The mean field is most efficient at
representing the periodic field, but the median field is more efficient
at representing the evolution of the diffuse field patterns.
---------------------------------------------------------
Title: The pattern of northern hemisphere surface air temperature
during prolonged periods of low solar output
Authors: Ruzmaikin, Alexander; Feynman, Joan; Jiang, Xun; Noone,
David C.; Waple, Anne M.; Yung, Yuk L.
2004GeoRL..3112201R Altcode:
We show that the reconstructed sensitivity of the sea level temperature
to long term solar forcing in the Northern Hemisphere is in very good
agreement with the empirical temperature pattern corresponding to
changes of the North Annular Mode (NAM). This implies that long-term
variations of solar output affect climate predominantly through the
NAM that extends throughout the stratosphere and troposphere.
---------------------------------------------------------
Title: The Influence of the QBO and Solar Variability on the North
Annular Mode.
Authors: Ruzmaikin, A.; Feynman, J.; Jiang, X.; Camp, C. D.; Yung, Y.
2004AGUSM.A14A..05R Altcode:
The Quasi-Biennial Oscillations (QBO) and solar variability are two
natural stratospheric forcings affecting atmospheric dynamics and
possibly climate. We study how these forcings affect the major mode
of the wintertime atmospheric variability in the Northern Hemisphere,
the North Annular Mode (NAM). This mode extends from the top of the
stratosphere through the troposphere to sea level accounting for 22%
of the variance in geopotential heights at sea level and more in
the stratosphere (Thompson and Wallace, 1998; Baldwin and Dunkerton,
1999). It has been found (Ruzmaikin and Feynman, 2002) that the NAM of
the coupled troposphere-stratosphere is influenced by decadal solar
variability. But the influence depends on the phase of the QBO and
phase of the winter season. Thus, in early (late) winter for the West
(East) QBO, the NAM is more positive for low UV than for high UV
fluxes. The effect was shown to be statistically significant. Here
we present the results of our search for a physical mechanism by
which the QBO and solar variability combined with seasonality affect
the NAM. Because the NAM is excited in the interplay between the
planetary waves and mean zonal wind (see for example Limpasuvan and
Hartmann, 2000), we investigate the latitudinal, vertical and time
distributions of the wave (EP) fluxes employing the NCEP Reanalysis
Data and the ECMWF Data. We also investigate the possible effect of the
QBO associated circulation on the NAM. References: Baldwin, M. P. and
T. J. Dunkerton, J. Geophys. Res. 104, 30,937, 1999; Limpasuvan, V., and
D. L. Hartmann, J. of Climate, 4414, 2000; Ruzmaikin, A., J, Feynman,
J. Geophys. Res., 107, D14, 10.1029/2001JD001239, 2002; Thompson,
D. W. J. and J. M. Wallace, Geophys. Res. Lett., 25, 1297, 1998.
---------------------------------------------------------
Title: Principal Component Analysis of the Latitudinal and
Longitudinal Structure of the Photospheric Magnetic Cycle
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
2004AAS...204.3708L Altcode: 2004BAAS...36Q.710L
We average magnetic fields in NSO synoptic maps over longitude and bin
the result by sin(latitude). Also, we average over a band of latitudes
and bin by longitude. A time stack of one-dimensional latitude "images"
resembles the Maunder butterfly diagram. Time stacks of longitude
"images" can be re-mapped to arbitrary rotation periods. <P />Principal
component analysis recombines images in a stack into mutually orthogonal
"empirical orthogonal functions" (EOFs). The EOFs are ordered by
how well each correlates with the full set of images. The principal
components (PCs) give the evolution of each EOF as a function of any
ordering parameter, such as time. The original data can be wholly or
partially reconstructed from subsets of the EOFs and their PCs. <P />Our
latitudinal EOFs have a few leaders whose PCs show both the 11/22-year
cycle and repeating substructure. Following are EOFs whose PCs show
the cycle but no repeated substructure. Next are EOFs with small scale
structure independent of the cycle. The least correlated EOFs contain
high latitude, mostly unipolar fields. We suggest associating these four
subsets of the EOFs with, respectively, global dynamo toroidal fields,
turbulently disordered structures fed by the toroidal fields, a possible
local surface dynamo process, and a global poloidal component. <P
/>We also studied a stack of longitudinal images of fields that were
averaged over latitude between N25 and N35 degrees. Two especially
active longitudes 180 degrees apart rotate with a period of 27.8
days. Structure at these longitudes dominates the leading EOFs. The
corresponding PCs are active over the whole span of the data. <P />This
work was supported by NASA Grant NAG5-10880. NSO/Kitt Peak data used
here are produced cooperatively by NSF/NOAO, NASA/GSFC, and NOAA/SEL.
---------------------------------------------------------
Title: Two-dimensional Empirical Orthogonal Functions of the
Photospheric Magnetic Cycle
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
2004AAS...204.3707C Altcode: 2004BAAS...36Q.710C
We carried out a principal component analysis (PCA) on sequences
of NSO magnetic flux synoptic maps by Carrington rotation. Two
data sets were investigated: (i) a sequence of 364 images from
Carrington rotation 1625 to 2007, with image size 360 x 180 pixels
(1 degree/pixel in longitude and sin(latitude)*90 in latitude for
both hemispheres); (ii) a sequence of 79 higher resolution maps of
size 1800 x 900 pixels starting at Carrington rotation 1913. The PCA
of a time series yields an eigenvalue spectrum, the corresponding
eigenfunctions (modes or "empirical orthogonal functions" (EOFs)),
and the principal components which describe the time evolution of the
modes. The dominant EOFs are associated with those structures that
remain spatially coherent throughout intervals of the time series,
and correspond to the functions with the highest eigenvalues. If the
eigenvalue spectrum is dominated by only a few large members, then
the corresponding few EOFs will mainly characterize the data. The rest
will contain transient fluctuations. We apply the technique to the two
dimensional maps and determine which EOFs dominate during different
times of the solar cycle. We find that the dominant modes are associated
with the active part of the cycle as expected, while the weaker modes
characterize the quiet periods. The increasing and declining phases
are associated with modes of intermediate eigenvalues. We reconstruct
the time series by projecting onto the three classes of modes and
investigate the probability distribution function (PDF) of "projected"
magnetic flux. We compare these results to the PDFs obtained from
artificial data generated by dynamo models. This work was supported
in part by Grant NASA-NAG5-10880. NSO/Kitt Peak data used here are
produced cooperatively by NSF/NOAO, NASA/GSFC, and NOAA/SEL.
---------------------------------------------------------
Title: The Sun's Preferred Longitudes and the Coupling of Magnetic
Dynamo Modes
Authors: Bigazzi, Alberto; Ruzmaikin, Alexander
2004ApJ...604..944B Altcode: 2003astro.ph.12212B
Observations show that solar activity is distributed
nonaxisymmetrically, concentrating at “preferred longitudes.” This
indicates the important role of nonaxisymmetric magnetic fields in
the origin of solar activity. We investigate the generation of the
nonaxisymmetric fields and their coupling with the axisymmetric solar
magnetic field. Our kinematic generation (dynamo) model operating in a
sphere includes a model of solar differential rotation, as obtained by
inversion of helioseismic data, modeled distributions of the turbulent
resistivity, nonaxisymmetric mean helicity, and meridional circulation
in the convection zone. We find that (1) the nonaxisymmetric modes are
localized near the base of the convection zone, where the formation of
active regions starts, and at latitudes around 30° (2) the coupling
of nonaxisymmetric and axisymmetric modes causes the nonaxisymmetric
mode to follow the solar cycle; the phase relations between the modes
are found; and (3) the rate of rotation of the first nonaxisymmetric
mode is close to that determined in interplanetary space.
---------------------------------------------------------
Title: A High-Speed Erupting-Prominence CME: A Bridge Between Types
Authors: Feynman, Joan; Ruzmaikin, Alexander
2004SoPh..219..301F Altcode:
Several studies have indicated that there may be two distinct types
of coronal mass ejections (CMEs); a high-velocity bright energetic
type associated with flares, and a smaller slower less impressive type
associated with erupting prominences. How valid is this distinction? We
analyze a CME combining attributes of both types, a high-velocity bright
CME associated with an erupting prominence. A study of this event
and several others allows us to argue that the apparent differences
separating the two types may be an observational effect. Our results
are consistent with a single CME process for both flare-associated and
filament-associated CMEs. This process consists of three stages. The
initial stage is brought about by the emergence of new magnetic flux,
which interacts with the pre-existing magnetic configuration and
results in a slow rise of the magnetic structure, which later becomes
the CME. The second stage is a fast reconnection phase with flaring and
a sudden increase of the rise velocity of the magnetic structure. It
also includes a rapidly increasing CME acceleration followed by a
rapidly falling acceleration. The third stage or CME propagation stage
shows only slow changes in the acceleration and finally the velocity
becomes constant. LASCO observes only the third stage. The differences
found between observed flare-associated and prominence-associated CME
velocity behavior appear to be primarily due to the relative heights
in the corona at which the erupting structures form.
---------------------------------------------------------
Title: A simple model of solar variability influence on climate
Authors: Ruzmaikin, Alexander; Lawrence, John K.; Cadavid, Ana Cristina
2004AdSpR..34..349R Altcode:
We present a simple dynamic model of solar variability influence on
climate, which is truncated from the stratospheric wave-zonal flow
interaction dynamics over a β-plane. The model consists of three
ordinary differential equations controlled by two parameters: the
initial amplitude of planetary waves and the vertical gradient of the
zonal wind. The changes associated with the solar UV variability, as
well as with seasonal variations, are introduced as periodic modulations
of the zonal wind gradient. Influence of the Quasi-Biennial Oscillation
is included as a periodic change of the width of the latitudinal extent
of the β-plane. The major climate response to these changes is seen
through modulation of the number of cold and warm winters.
---------------------------------------------------------
Title: Preferred longitudes and the solar dynamo.
Authors: Bigazzi, A.; Ruzmaikin, A.
2004cosp...35.3578B Altcode: 2004cosp.meet.3578B
Magnetic activity in the Sun tends to cluster at preferred longitudes,
giving rise to non-axisymmetric structures. The origin of this
phenomenon is unclear. Dynamo theory has not consistently addressed
this outstanding feature of solar magnetism, so far. We discuss the
dynamics of the non--axisymmetric modes of the large--scale fields and
show its possible connections with the phenomena of preferred longitudes
and the clustering of magnetic activity. In our mean--field model, a
non-axisymmetric alpha-effect, possibly originating from instabilities
of the flow field, couples together the longitudinal modes of the
dynamo. The amplitude of the modes thus generated is modulated in time
following the solar cycle, in agreement with the observed phase shift
between the axisymmetric field, which reaches its largest amplitude
close to solar minimum, and the non-axisymmetric field, which is
larger close to solar maximum. Unlike the axisymmetric fields,
the non-axisymmetric ones are influenced by the radial structure
of the solar rotation rate. As a result, they concentrate in a
region around 30° latitude, where the radial gradient of the solar
rotation is minimal as shown by helioseismology. This may contribute
to understanding the origin of the latitudinal distribution of sunspots
through the cycle. The non-axisymmetric modes represent rigid patterns
rotating in longitude with a rate determined by the solutions of the
dynamo equations. This rate can be measured and checked against that of
the oscillating magnetic features found in the interplanetary medium,
or against the rotation rate of the tilted dipole field reconstructed
during the last fast scan of the Ulysses spacecraft, returning a value
close to the core rotation rate.
---------------------------------------------------------
Title: Influence of Photospheric Magnetic Fields and Dynamics on
Chromospheric K-Line Emission
Authors: Lawrence, J. K.; Cadavid, A. C.; Miccolis, D.; Berger, T. E.;
Ruzmaikin, A.
2003ApJ...597.1178L Altcode:
We analyze a 9 hr sequence of simultaneous, high-resolution,
high-cadence G-band and K-line solar filtergrams plus magnetograms
of lower cadence and resolution. Images include both network
and internetwork. The magnetic and filtergram intensities, their
fluctuations, and relative phases change with progressive strengthening
of local magnetic field. At increased flux levels, sudden photospheric
downflows create long-lived magnetic elements. For weak magnetic fields
the K-line and G-band intensities include an oscillatory component
with period 4 minutes. For stronger fields, the K-line period shifts
to 5 minutes, while the G-band fluctuations fade due to dissociation
of their source, the CH radical. These K-line and G-band fluctuations,
whose periods are longer than the acoustic cutoff, are coherent and
in phase. They also are coherent with fluctuations of the magnetic
field. Weak-field magnetic fluctuations lead the intensity fluctuations
by a phase shift of 90°. Strong-field magnetic fluctuations trail the
intensities by 100°. These are interpreted as standing waves in the
photosphere and low chromosphere. Another class of G-band fluctuations,
with periods shorter than the acoustic cutoff, is associated both
with stronger magnetic fields and with enhanced K-line emission with
fluctuations longer than the cutoff period. This suggests waves excited
by rapid photospheric perturbations and propagating up along magnetic
flux tubes.
---------------------------------------------------------
Title: Multi-Angle Viewing of the Sun and the Inner Heliosphere
Authors: Ruzmaikin, Alexander
2003AIPC..679..826R Altcode:
We describe the concept of a proposed mission, called Multi-Angle Solar
Sources Explorer (MASSÉ), that would observe the Sun and the inner
Heliosphere from an orbit at 0.72 AU over all solar longitudes. It
would, in coordination with observations from Earth's side, investigate
the sources of solar activity from their origin deep within the Sun,
their emergence onto the photosphere, and their ejection into the
Heliosphere. It carries a Doppler-magnetic imager, and in situ energetic
particle, solar wind, and magnetic field detectors. Three-dimensional
views of the convection zone, where solar activity originates, are
reconstructed by correlating MASSÉ and earth-side Doppler signals
from acoustic wave packets traversing deep solar layers. Magnetic
images reveal the evolution of active regions over their life-time
and allow the study of emerging fields from deep layers. Particle,
plasma, and magnetic field data provide information on the sites and
mechanisms of acceleration of hazardous high-energy particles produced
by coronal mass ejections.
---------------------------------------------------------
Title: Influence of Photospheric Magnetism and Dynamics on
Chromospheric K-line Emission
Authors: Lawrence, J. K.; Cadavid, A. C.; Miccolis, D.; Berger, T. E.;
Ruzmaikin, A.
2003SPD....34.0704L Altcode: 2003BAAS...35..820L
We analyze a unique 9 hr sequence of near simultaneous, high resolution
and high cadence G-band and K-line SVST solar filtergrams together
with magnetograms of lower cadence and resolution. We focus on a
region of the solar surface that includes both internetwork and
network. We examine how the (temperature minimum/chromospheric)
CaII K-line and (photospheric) G-band intensities, their temporal
fluctuations and their coherence and phase relations, with each other
and with magnetic fluctuations, change as we progress from weak magnetic
fields (internetwork) to intermediate and strong fields (network). <P
/>As the background level of flux is increased, sudden photospheric
downflow events can create long-lived, compact (i.e. network) magnetic
elements. For weak magnetic fields the K-line and G-band intensity
signals show an oscillatory component with period centered on 4 min. As
we pass to strong fields, the K-line signal shifts to a 5 min period
while the G-band signal fades, presumably due to dissociation of the
CH radical. The K-line and G-band signals are coherent and nearly
in-phase. They are both coherent with fluctuations of the magnetic
field. For weak field the magnetic signal leads the intensity signals by
90<SUP>o</SUP> in phase. For intermediate and strong fields the magnetic
signal trails the intensities by 110<SUP>o</SUP>. We interpret this as
a transition from acoustic standing waves with weak, passive magnetic
field to a slow mode trapped magnetoacoustic wave. For intermediate
magnetic field we find, in addition to the coherent waves, that G-band
fluctuations at frequencies above the acoustic cutoff (period <
3.5 min) are associated with magnetic fields and with K-line emission
at periods > 3.5 min. This suggests the presence of flux tube
waves excited by rapid photospheric perturbations. <P />This work
was supported by grants NSF-ATM 9987305 and NASA-NAG5-10880. The SVST
is operated by the Swedish Royal Academy of Sciences at the Spanish
Observatorio del Roque de los Muchachos of the Instituto de Astrofisica
de Canarias.
---------------------------------------------------------
Title: A Simple Model of Stratospheric Dynamics Including Solar
Variability.
Authors: Ruzmaikin, Alexander; Lawrence, John; Cadavid, Cristina
2003JCli...16.1593R Altcode:
A simple dynamic model, truncated from the stratospheric wave-zonal
flow interaction Holton and Mass model, is introduced and studied. This
model consists of three ordinary differential equations controlled
by two parameters: the initial amplitude of planetary waves and the
vertical gradient of the zonal wind. The changes associated with
seasonal variations and with the solar variability are introduced as
periodic modulations of the zonal wind gradient. The major climatic
response to these changes is seen through modulation of the number of
cold and warm winters.
---------------------------------------------------------
Title: Photospheric Sources of Chromospheric Dynamics in the
Internetwork
Authors: Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.; Ruzmaikin, A.
2003SPD....34.0703C Altcode: 2003BAAS...35..820C
We analyze a unique 9 hr sequence of near simultaneous, high
resolution and high cadence G-band and K-line solar filtergrams
together with magnetograms of lower cadence and resolution, taken
with the SVST. We investigate an internetwork region characterized
by magnetic fields with strength < 150 Gauss and focus on the
phenomena surrounding discrete photospheric darkening “events”
in G-band intensities. 72 % of the darkenings are followed after 2
min by K-line brightenings. In the remaining cases the darkenings are
instead preceded by K-line brightenings 2 min earlier. In both cases
the preceding and following G-band minima are each associated with
transient magnetic enhancements, and thus, presumably, photospheric
inflows followed by outflows. The magnetic field appears to have no
role in coupling the photospheric phenomena to the chromosphere, and
acts as a passive tracer of horizontal photospheric flows that converge
on the photospheric darkening events and then rebound. The timing and
coupling of the photospheric darkenings and chromospheric brightenings
appear to be regulated by a pre-existing 4 min oscillation of the
solar atmosphere. Other oscillations with periods in the range 1-8
min also are present, and in general the wave power is doubled at the
time of an event. At short periods temporal structure is resolved. Our
results favor an acoustic source for enhanced amplitudes of K-line
intensity oscillations.
---------------------------------------------------------
Title: Photospheric Sources and Brightening of the Internetwork
Chromosphere
Authors: Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.; Ruzmaikin, A.
2003ApJ...586.1409C Altcode:
We analyze a unique 9 hr sequence of near-simultaneous, high-resolution
and high-cadence G-band and K-line solar filtergrams, together with
magnetograms of lower cadence and resolution. Our focus is on the
phenomena surrounding discrete photospheric darkening “events” in
internetwork G-band intensities. 72% of the darkenings are followed
after 2 minutes by K-line brightenings. In the remaining cases,
the darkenings are instead preceded by K-line brightenings 2 minutes
earlier. Equivalent results are found when reference is shifted to
K-line brightening events, although these two sets overlap by no more
than 15%. The timing and coupling of the photospheric darkenings and
chromospheric brightenings appear to be regulated by a preexisting 4
minute oscillation of the solar atmosphere. Other oscillations with
periods in the range 1-8 minutes also are present, and in general
the wave power is doubled at the time of an event. Our results
favor an acoustic source for enhanced amplitudes of K-line intensity
oscillations. The magnetic field acts as a passive tracer of horizontal
photospheric flows that converge on the photospheric darkening events
and then rebound.
---------------------------------------------------------
Title: Signs of magnetic helicity in interplanetary coronal mass
ejections and associated prominences: Case study
Authors: Ruzmaikin, Alexander; Martin, Sara; Hu, Qiang
2003JGRA..108.1096R Altcode:
We study the distribution of magnetic helicity in interplanetary coronal
mass ejections (CMEs) separated into magnetic clouds and remnants of
the prominence structures for three cases with identified remnants
of prominences. The magnetic configurations of magnetic clouds and
prominence remnants can satisfactorily be described by the flux rope
approximation. It is shown that the magnetic helicities in both parts of
the CMEs have the same sign. This sign is consistent with the dominance
of CMEs with negative helicity in the northern hemisphere and positive
in the southern hemisphere. The results are discussed in the context
of different models of CME eruption at the Sun.
---------------------------------------------------------
Title: Helioseismic probing of the solar dynamo
Authors: Ruzmaikin, Alexander; Lindsey, Charles
2003ESASP.517...71R Altcode: 2003soho...12...71R
According to theoretical predictions, the solar dynamo operating in
the convection zone generates maximal magnetic fields near the base
of the convection zone. Detection of this field is a challenging task
for helioseismology. We discuss the ways of probing the magnetic field
in the solar interior and estimate the magnitude of the field that can
be detected with presently achievable accuracy. It is easier, however,
to detect the flows that drive the dynamo. We describe the major flow
parameters related to the dynamo flows and present the requirements
for measurement of these parameters with local helioseismic techniques.
---------------------------------------------------------
Title: The magnetic field in the convection zone
Authors: Bigazzi, Alberto; Ruzmaikin, Alexander A.
2003ESASP.517..239B Altcode: 2002astro.ph.11116B; 2003soho...12..239B
One of the key questions in solar physics that remains to be answered
concerns the strength and the distribution of the magnetic fields at
the base of the convection zone. The flux tube dynamics requires that
toroidal fields of strength as large as 100 kilogauss be present at
the base of the convection zone. The kinetic-magnetic equipartition
argument leads to smaller field strengths. For possible detection
of these relatively small (compared to pressure effects) fields by
helioseismic methods it is important to know the range of the field
strengths and their distribution. We estimate a range for the toroidal
magnetic field strengths at the base of the convection zone using
dynamo simulations in a spherical shell. These simulations involve the
distribution of rotation provided by helioseismic inversions of the GONG
and MDI data. Combining the simulations with the observed line-of-sight
surface poloidal field we extract the spatial pattern and magnitude
of the mean toroidal magnetic field at the base of the convection zone.
---------------------------------------------------------
Title: The JPL proton fluence model: an update
Authors: Feynman, Joan; Ruzmaikin, Alexander; Berdichevsky, Victor
2002JASTP..64.1679F Altcode: 2002JATP...64.1679F
The development of new technologies and the miniaturization of sensors
bring new requirements for our ability to predict and forecast hazardous
space weather conditions. Of particular importance are protons in
the energy range from 10s to 100s of MeV which cause electronic part
and solar cell degradation, and pose a hazard to biological systems
in space and to personnel in polar orbit. Sporadic high-energy solar
particle events are a main contributor to the fluences and fluxes of
such protons. A statistical model, JPL 1991 (J. Geophys. Res. 98 (1991)
13,281), was developed to specify fluences for spacecraft design and is
now widely used. Several major solar proton events have occurred since
that model was developed and one objective of this paper is to see if
changes need to be made in the model due to these recent events. Another
objective is to review the methods used in JPL 1991 in the light of new
understandings and to compare the JPL methods with those used in other
models. We conclude that the method used in developing JPL 1991 model
is valid and that the solar events occurring since then are completely
consistent with the 1991 model. Since no changes are needed we suggest
that the name of the model be changed to “the JPL fluence model”.
---------------------------------------------------------
Title: Multi-angle exploration of the Sun
Authors: Ruzmaikin, Alexander
2002ESASP.505...53R Altcode: 2002IAUCo.188...53R; 2002solm.conf...53R
We describe the concept of a proposed new mission, called Multi-Angle
Solar Sources Explorer (MASSÉ), that would observe the Sun from
an orbit at 0.72 AU and over all solar longitudes. It would, in
coordination with observations taken from Earth's side, investigate
the sources of solar activity from their origin deep within the Sun,
their emergence onto the photosphere, and their ejection into the
heliosphere. It carries a Doppler-magnetic imager, and in situ energetic
particle, solar wind, and magnetic field detectors. Three-dimensional
views of the convection zone, where solar activity originates, are
reconstructed by correlating MASSÉ and Earth-side Doppler signals from
acoustic wave packets traversing deep solar layers. Magnetic images
reveal the evolution of active regions over the entire solar surface and
allow the study of emerging fields from deep layers. MASSÉ particle,
plasma, and magnetic field data provide information on the sites and
mechanisms of acceleration of hazardous high-energy particles produced
by coronal mass ejections.
---------------------------------------------------------
Title: Observations of the Structure of small scale photospheric
fields
Authors: Lawrence, J.; Cadavid, A.; Ruzmaikin, A.; Berger, T.
2002ocnd.confE..26L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A simple model of solar variability influence on climate.
Authors: Ruzmaikin, A.; Lawrence, J.; Cadavid, A.
2002cosp...34E.336R Altcode: 2002cosp.meetE.336R
We introduce and study a simple dynamic model of solar influence on
climate. The model is truncated from the stratospheric wave-zonal
flow interaction model suggested by Holton and Mass (1976). Our model
consists of three ordinary differential equations controlled by two
parameters: the initial amplitude of planetary waves and the vertical
gradient of the zonal wind. The changes associated with seasonal
variations and with the solar variability are introduced as periodic
modulations of the zonal wind gradient. The major atmospheric response
to these changes is seen through modulation of the number of cold and
warm winters.
---------------------------------------------------------
Title: A search for the source spectrum of solar wind fluctuations
Authors: Ruzmaikin, Alexander
2001ESASP.493..455R Altcode: 2001sefs.work..455R
No abstract at ADS
---------------------------------------------------------
Title: Strength and phase of the solar dynamo during the last
12 cycles
Authors: Ruzmaikin, A.; Feynman, J.
2001JGR...10615783R Altcode:
We use the aa index of geomagnetic activity recorded for 130 years to
study the strength and phase properties of the solar dynamo. We split
the monthly averaged aa into two parts: one part proportional to the
sunspot number and the other part proportional to the residual. We
argue that the first part is a proxy for the solar dynamo's large-scale
mean toroidal magnetic field. The residual has the same periodicity as
the sunspot cycle and has closely related amplitude, but is shifted
in phase. We relate this residual to the poloidal field generated
from the toroidal field in the dynamo process. The changes in both
components demonstrate that there was a long-term trend in the strength
and relative phases of the toroidal and poloidal components of the
mean-field dynamo. The changes in the relative phase of the toroidal
and poloidal fields suggest that the distributions of the differential
rotation and helicity within the Sun's convection zone have changed
over timescales of 50 years.
---------------------------------------------------------
Title: Mesogranulation and Turbulence in Photospheric Flows
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
2001SoPh..202...27L Altcode: 2001astro.ph..4354L
Below the scale of supergranules we find that cellular flows are present
in the solar photosphere at two distinct size scales, approximately 2 Mm
and 4 Mm, with distinct characteristic times. Simultaneously present in
the flow is a non-cellular component, with turbulent scaling properties
and containing 30% of the flow energy. These results are obtained by
means of wavelet spectral analysis and modeling of vertical photospheric
motions in a 2-hour sequence of 120 SOHO/MDI, high-resolution, Doppler
images near disk center. The wavelets permit detection of specific
local flow patterns corresponding to convection cells.
---------------------------------------------------------
Title: Spatiotemporal Scaling of Solar Surface Flows
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.; Berger, T. E.
2001PhRvL..86.5894L Altcode: 2001astro.ph..1224L
The sun provides an excellent natural laboratory for nonlinear
phenomena. We use motions of magnetic bright points on the solar
surface, at the smallest scales yet observed, to study the small scale
dynamics of the photospheric plasma. The paths of the bright points
are analyzed within a continuous time random walk framework. Their
spatial and temporal scaling suggests that the observed motions are
the walks of imperfectly correlated tracers on a turbulent fluid flow
in the lanes between granular convection cells.
---------------------------------------------------------
Title: Preferred solar longitudes with signatures in the solar wind
Authors: Ruzmaikin, A.; Feynman, J.; Neugebauer, M.; Smith, E. J.
2001JGR...106.8363R Altcode:
Using spacecraft data collected over three solar cycles, Neugebauer et
al. [2000] found a persistent dependence of the solar wind speed and
the radial component of the interplanetary magnetic field on solar
longitude, defined in a coordinate system with a rotation period
of 27.03 days. Here we investigate the solar source of this period
using observations of the photospheric magnetic field. We study the
lowest-order nonaxisymmetric modes of the solar field extracted from
synoptic charts of the Wilcox Solar Observatory. We find there is a
robust magnetic structure on the Sun, which rotates with the period
found by Neugebauer et al. [2000] in the solar wind. This rotation is
more rapid than the solar equatorial and core rotations. We discuss
the association of this nonaxisymmetric mode with the magnetic field
generated by the solar mean field dynamo.
---------------------------------------------------------
Title: Magnetic Footpoint Motions and Superdiffusion
Authors: Cadavid, C.; Lawrence, J.; Ruzmaikin, A.
2001AGUSM..SP51B07C Altcode:
In order to study the properties of the velocities of magnetic foot
points in the photosphere, we analyzed the dynamics of magnetic G-band
bright points (MBP's) from data obtained at the Swedish Vacuum Solar
Telescope. Almost universally, random walks and diffusion are studied by
looking at the square of the displacement of an average fluid element in
a given time. For normal diffusion the scaling exponent that describes
the relation of the mean squared displacement to the time has a value
of 1. However this approach is inadequate for the study of the observed
motions, since the magnetic features are stopped in their motion at
“traps” in the intergranular lanes. Additionally we only have access
to a limited amount of data. A more reliable characterization of the
fluid motions is obtained from low statistical moments, such as the
square root, or lower, of the displacements. In this case the scaling
exponent is 1.4. The motions are therefore superdiffusive: faster
than normal but slower than purely fluid turbulence. This not only
reveals turbulent dynamics between convection cells on the Sun, but
also gives quantitative information on the coupling of magnetic fields
to the solar flows. In turn these superdiffusive motions can be used to
drive the footpoints of magnetic flux tubes in a model of chromospheric
heating. This is a more realistic approach than using Gaussian noise
to approximate the turbulence component to the velocity field.
---------------------------------------------------------
Title: Mesogranulation and Turbulence in Photospheric Flows
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
2001AGUSM..SP41C02L Altcode:
Cellular flows are present in the solar photosphere at two
distinct size scales, 2 Mm and 4 Mm, with distinct characteristic
times. Simultaneously present in the flow is a non-cellular component,
with turbulent scaling properties between 1 Mm and 64 Mm, and containing
30 % of the flow energy. These results are obtained by means of wavelet
spectral analysis and modeling of vertical photospheric motions in
a 2-hour sequence of 120 SOHO/MDI, high resolution, Doppler images
near disk center. The wavelets permit detection of specific local flow
patterns corresponding to convection cells. Standard spectral techniques
have difficulty resolving mesogranules for three basic reasons: (1) the
mesogranules are near in scale to granules and weaker in velocity and
(2) they are hidden by overlying turbulence because (3) global basis
functions, such as Fourier waves or spherical harmonics, do not allow
attention to be paid to the local topologies that label cellular flows.
---------------------------------------------------------
Title: Origin of Sunspots
Authors: Ruzmaikin, Alexander
2001SSRv...95...43R Altcode:
Sunspots, seen as cool regions on the surface of the Sun, are a thermal
phenomenon. Sunspots are always associated with bipolar magnetic loops
that break through the solar surface. Thus to explain the origin of
sunspots we have to understand how the magnetic field originates inside
the Sun and emerges at its surface. The field predicted by mean-field
dynamo theories is too weak by itself to emerge at the surface of the
Sun. However, because of the turbulent character of solar convection
the fields generated by dynamo are intermittent - i.e., concentrated
into ropes or sheets with large spaces in between. The intermittent
fields are sufficiently strong to be able to emerge at the solar
surface, in spite of the fact that their mean (average) value is
weak. It is suggested here that magnetic fields emerge at the solar
surface at those random times and places when the total magnetic field
(mean field plus fluctuations) exceeds the threshold for buoyancy. The
clustering of coherently emerged loops results in the formation of a
sunspot. A non-axisymmetric enhancement of the underlying magnetic
field causes in the clustering of sunspots forming sunspot groups,
clusters of activity and active longitudes. The mean field, which
is not directly observable, is also important, being responsible for
the ensemble regularities of sunspots, such as Hale's law of sunspot
polarities and the 11-year periodicity.
---------------------------------------------------------
Title: Rate of helicity production by solar rotation
Authors: Berger, Mitchell A.; Ruzmaikin, Alexander
2000JGR...10510481B Altcode:
In recent years, solar observers have discovered a striking pattern in
the distribution of coronal magnetic structures: northern hemisphere
structures tend to have negative magnetic helicity, while structures in
the south tend to have positive magnetic helicity. This hemispheric
dependence extends from photospheric observations to in situ
measurements of magnetic clouds in the solar wind. Understanding the
source of the hemispheric sign dependence, as well as its implications
for solar and space physics has become known as the solar chirality
problem. Rotation of open fields creates the Parker spiral which carries
outward 10<SUP>47</SUP>Mx<SUP>2</SUP> of magnetic helicity (in each
hemisphere) during a solar cycle. In addition, rough estimates suggest
that each hemisphere sheds on the order 10<SUP>45</SUP>Mx<SUP>2</SUP>
in coronal mass ejections each cycle. Both the α effect (arising
from helical turbulence) and the Ω effect (arising from differential
rotation) should contribute to the hemispheric chirality. We show that
the Ω effect contribution can be captured in a surface integral, even
though the helicity itself is stored deep in the convection zone. We
then evaluate this surface integral using solar magnetogram data and
differential rotation curves. Throughout the 22 year cycle studied
(1976-1998) the helicity production in the interior by differential
rotation had the correct sign compared to observations of coronal
structures-negative in the north and positive in the south. The net
helicity flow into each hemisphere over this cycle was approximately
4×10<SUP>46</SUP>Mx<SUP>2</SUP>. For comparison, we estimate the
α effect contribution; this may well be as high or higher than the
differential rotation contribution. The subsurface helicity can be
transported to the corona with buoyant rising flux tubes. Evidently
only a small fraction of the subsurface helicity escapes to the surface
to supply coronal mass ejections.
---------------------------------------------------------
Title: Response to weak solar forcing in a general circulation model
of the atmosphere.
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
2000BAAS...32R.832C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Random Walks of Magnetic Bright Points and Coronal Loop Heating
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
2000AAS...196.4903L Altcode: 2000BAAS...32..750L
The random walks of small-scale ( ~ 0.2 arcsec) magnetic bright points
(MBPs) in the lanes between photospheric granules are anomalous. The
temporal growth of the q-th moment of the displacement r(t) is a
power law with exponent q γ (q)/2. For normal, Gaussian walks γ
(q)= 1 for all q. However, for the MBP walks on time scales <
45 minutes we find that γ (2)<1 and that γ (q) is a decreasing
function of q. Many viable models for the heating of coronal loops are
based on the additon of energy via twisting and braiding of magnetic
flux lines by the random motions of their footpoints. If the MBPs are
associated with such footpoints, then the statistics of their motions
are directly relevant to coronal heating. For example, a number of
models derive heating rates based on moments of the displacements and
include the standard assumption that γ = 1. However, this assumption
is wrong for MBPs, and the actual value of γ depends on exactly which
moment enters the expression. All such models are therefore subject to
modification. The result γ (2)<1 is a result of pauses in the MBP
walks on all time scales (”fractal time”) up to ~ 45 min. This implies
that the motions of an individual footpoint are not statistically
stationary. This in turn means that the injection of energy into a
given loop will be strongly variable and intermittent. This can be
related to observations of the details of variability in coronal loop
emissions, giving information on the locations of energy deposition and
on time scales of energy release. We thus hope to further constrain
acceptable heating models. This work was supported in part by NSF
Grant ATM-9628882.
---------------------------------------------------------
Title: Response to Weak Solar Forcing in a General Circulation Model
of the Atmosphere
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
2000SPD....3102117C Altcode: 2000BAAS...32..832C
We study the effect of variable external forcing on a dynamical
system proposed by Lorenz as a simple general circulation model of
the atmosphere. When a strong annual cycle is included, numerical
exploration reveals the existence of a variety of multi-year climate
states, which fall into two basic types. In the space of external
forcing parameters, the different kinds of climate state are interleaved
in an intricate pattern at scales < 0.01. This is below the ~ 0.1
level of observed solar cycle irradiance variability which can thus
modulate the model climate state. If the solar cycle is accompanied
by a steady drift in forcing, it can produce periodic modulation
which appears, disappears and even reverses its phase. A parametric
drift by itself produces intervals of steady, but sometimes differing,
climates punctuated by intermittent bursts of variability. Different
forcing parameters for the Northern and Southern Hemispheres produce
different responses to variable forcing.
---------------------------------------------------------
Title: On the Nature and Persistence of Preferred Longitudes of
Solar Activity.
Authors: Ruzmaikin, A. A.; Feynman, J.; Neugebauer, M.; Smith, E. J.
2000SPD....31.0404R Altcode: 2000BAAS...32..835R
Several studies of the distribution of activity on the solar surface
indicate preferred longitude patterns sometimes lasting longer than a
solar cycle. We have analyzed 150 years of daily sunspot number and
find evidence for a preferred longitude zone that persisted over 13
solar cycles. The relative intensity of the preferred zone varied from
cycle to cycle and, in some individual cycles the preference was not
evident. This complements the recent analysis of the measured solar
wind speed and interplanetary magnetic field over more than three
solar cycles, which implied that the solar magnetic moment returned
to the same longitude after each reversal (Neugebauer et al., JGR,
105, 2315, 2000). These findings suggest a long-term memory built into
the mechanism generating the solar magnetic field responsible for the
activity. The solar magnetic field is generated by a dynamo located
near the bottom of the convection zone. A particular role is played
by a thin tachocline layer on the border between the convection
zone and the radiative core. The structure and motions inferred
from helioseismic data and models do not, however, indicate any
preferred longitude. Preferred longitudes can arise due to excitation
of non-axisymmetric magnetic modes. These modes have been invoked
for explanation of clustering of emerging activity (Ruzmaikin, Solar
Phys., 182, 1, 1998). The solar magnetic moment is determined by the
sum of the axisymmetric (m = 0) and the first non-axisymmetric (m =
1) mode. We will discuss the conditions of excitation and persistence
of non-axisymmetric modes on the Sun implied by the results of our
data analyses. The work was performed in part for the Jet Propulsion
Laboratory, California Institute of Technology, under a contract with
the National Aeronautics and Space Administration.
---------------------------------------------------------
Title: Can We Get the Bottom B?
Authors: Ruzmaikin, Alexander
2000SoPh..192...49R Altcode:
Understanding the solar dynamics and the origin of active regions
depends crucially on our knowledge of the magnetic fields deep within
the convection zone. Can we determine magnetic fields there? Some
clues are given by dynamo theories and modeling of those instabilities
in the convection zone which result in the emergence of magnetic
flux. Magnetic field generated by dynamo is predominantly azimuthal
and believed to be unstable to the formation of flux tubes. Simulations
indicate that the emergence of the magnetic flux tubes strongly depends
on the field strength and its longitudinal distribution at the bottom
of the convection zone. In a unifying approach advocated in this
paper the solar magnetic field is split into a mean part generated
by the mean-field dynamo and a fluctuating part approximated by an
ensemble of flux tubes. Observationally, the identification of the
longitudinal distribution of emerging photospheric magnetic fields
can give us information about the magnetic field strength at the
bottom of the convection zone. Distinguishing between the modes of
emerging field requires simultaneous magnetic imaging of both sides of
the Sun. Correlation of simultaneous Dopplergrams of the photosphere
from earthside and from the farside of the Sun opens an opportunity
to detect velocity structures at the base of the convection zone,
associated with the dynamo and emerging active regions. This global
imaging of the photosphere can also be used for detection of a magnetic
field in the solar core.
---------------------------------------------------------
Title: The solar magnetic field and the solar wind: Existence of
preferred longitudes
Authors: Neugebauer, M.; Smith, E. J.; Ruzmaikin, A.; Feynman, J.;
Vaughan, A. H.
2000JGR...105.2315N Altcode:
Direct measurements of the solar wind speed and the radial component
of the interplanetary magnetic field acquired over more than three
solar cycles are used to search for signatures of a persistent
dependence of solar wind properties on solar longitude. Two methods
of analysis are used. One finds the rotation period that maximizes
the amplitude of longitudinal variations of both interplanetary
and near-Earth data mapped to the Sun. The other is based on power
spectra of near-Earth and near-Venus data. The two methods give the
same result. Preferred-longitude effects are found for a synodic solar
rotation period of 27.03+/-0.02 days. Such high precision is attained by
using several hundred thousand hourly averages of the solar wind speed
and magnetic field. The 27.03-day periodicity is dominant only over
long periods of time; other periodicities are often more prominent for
shorter intervals such as a single solar cycle or less. The 27.03-day
signal is stronger and more consistent in the magnetic field than in
the solar wind speed and is stronger for intervals of high and declining
solar activity than for intervals of low or rising activity. On average,
solar magnetic field lines in the ecliptic plane point outward on
one side of the Sun and inward on the other, reversing direction
approximately every 11 years while maintaining the same phase. The
data are consistent with a model in which the solar magnetic dipole
returns to the same longitude after each reversal.
---------------------------------------------------------
Title: Anomalous Diffusion of Solar Magnetic Elements
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
1999ApJ...521..844C Altcode:
The diffusion properties of photospheric bright points associated
with magnetic elements (magnetic bright points) in the granulation
network are analyzed. We find that the transport is subdiffusive
for times less than 20 minutes but normal for times larger than 25
minutes. The subdiffusive transport is caused by the walkers being
trapped at stagnation points in the intercellular pattern. We find
that the distribution of waiting times at the trap sites obeys a
truncated Lévy type (power-law) distribution. The fractal dimension
of the pattern of sites available to the random walk is less than 2
for the subdiffusive range and tends to 2 in the normal diffusion
range. We show how the continuous time random walk formalism can
give an analytical explanation of the observations. We simulate this
random walk by using a version of a phenomenological model of renewing
cells introduced originally for supergranules by Simon, Title, &
Weiss. We find that the traps that cause the subdiffusive transport
arise when the renewed convection cell pattern is neither fixed nor
totally uncorrelated from the old pattern, as required in Leighton's
model, but in some intermediate state between these extremes.
---------------------------------------------------------
Title: Can El Nińo amplify the solar forcing of climate?
Authors: Ruzmaikin, A.
1999GeoRL..26.2255R Altcode:
ENSO (El Nińo and the Southern Oscillation) is considered as
a stochastic driver that excites the atmospheric anomaly states,
such as Pacific North American pattern. This can make 11-year solar
activity forcing of climate feasible through stochastic resonance-a
mechanism that amplifies a weak input to a nonlinear bistable system
by the assistance of noise.
---------------------------------------------------------
Title: Modulation of cosmic ray precipitation related to climate
Authors: Feynman, J.; Ruzmaikin, A.
1999GeoRL..26.2057F Altcode:
High energy cosmic rays may influence the formation of clouds
and thus impact weather and climate. Due to systematic solar wind
changes, the intensity of cosmic rays incident on the magnetopause
has decreased markedly during this century. The pattern of cosmic ray
precipitation through the magnetosphere to the upper troposphere has
also changed. Early in the century, the part of the troposphere open
to cosmic rays of all energies was typically confined to a relatively
small high-latitude region. As the century progressed the size of this
region increased by over 25% and there was a 6.5° equatorward shift
in the yearly averaged latitudinal position of the subauroral region
in which cloud cover has been shown to be cosmic ray flux dependent. We
suggest these changes in cosmic ray intensity and latitude distribution
may have influenced climate change during the last 100 years.
---------------------------------------------------------
Title: Three-dimensional Magnetohydrodynamic Simulationsof the
Interaction of Magnetic Flux Tubes
Authors: Kondrashov, D.; Feynman, J.; Liewer, P. C.; Ruzmaikin, A.
1999ApJ...519..884K Altcode:
We use a three-dimensional Cartesian resistive MHD code to investigate
three-dimensional aspects of the interaction of magnetic flux
tubes as observed in the solar atmosphere and studied in laboratory
experiments. We present here the first results from modeling the
reconnection of two Gold-Hoyle magnetic flux tubes that follow the
system evolution to a final steady state. The energy evolution and
reconnection rate for flux tubes with both parallel and antiparallel
axial fields and with equal and nonequal strengths are studied. For the
first time, we calculate a gauge-invariant relative magnetic helicity
of the system and compare its evolution for all the above cases. We
observed that the rate at which helicity is dissipated may vary
significantly for different cases, and it may be comparable with the
energy dissipation rate. The footpoints of the interacting flux tubes
were held fixed or allowed to move to simulate different conditions
in the solar photosphere. The cases with fixed footpoints had lower
magnetic energy release and reached a steady state faster than cases
with moving footpoints. For all computed cases the magnetic energy was
released mostly through work done on the plasma by the electromagnetic
forces rather than through resistive dissipation. The reconnection rate
of the poloidal magnetic field is faster for the case with antiparallel
flux tubes than for the case with parallel flux tubes, consistent with
laboratory experiments. We find that during reconnection supersonic (but
sub-Alfvénic) flows develop, and it may take a considerably longer
time for the system to reach a steady state than for magnetic flux
to reconnect. It is necessary to retain the pressure gradient in the
momentum equation; the plasma pressure may be significant for the final
equilibrium steady state even with low-β initial conditions, and the
work done on the plasma by compression is important in energy exchange.
---------------------------------------------------------
Title: On generation of high-frequency Alfvén waves in the solar
corona
Authors: Ruzmaikin, Alexander; Berger, Mitchell A.
1999AIPC..471..325R Altcode: 1999sowi.conf..325R
We discuss a source for high-frequency Alfvén waves, associated with
twisted magnetic loops emerging on the solar surface and reconnecting
with the open field. We identify the loops with the ephemeral regions
(small-scale bipoles) observed by ground-based instruments and by
SOHO. To characterize the loops we employ the concept of a minimum
energy state for topologically complex fields. Our estimates of the
power that can be released and the range of wave frequencies marginally
agree with models of coronal heating and acceleration of the solar wind
by high-frequency Alfvén waves. We suggest that severe requirements
on the upper-bound frequency, used in these models, can be relaxed by
taking into account the energy released due to reconnections within
magnetic loops whose footpoints are twisted by surface convective
motions. This presentation updates our more extended discussion of
the source of coronal heating (1).
---------------------------------------------------------
Title: Sun-Earth Connection Observatory (SECO)
Authors: Ruzmaikin, A.
1999AAS...194.7602R Altcode: 1999BAAS...31Q.956R
To understand fundamentals of Sun-Earth Connections in general and
Space Weather in particular, full-Sun viewing is required. A minimal
mission includes simultaneous observations from behind the Sun and
from the earthside. This mission will bring understanding of how
geoeffective solar magnetic activity originates by: (1) following
magnetic activity from its source in the solar interior to the solar
surface using deep helioseismic probing, (2) continuously observing the
solar surface development of sources of geoeffective (fast) CMEs and
particle events using Doppler-magnetic imaging, (3) observing coronal
magnetic fields using Faraday rotation measurements deconvolved by
modeling with full-Sun boundary conditions obtained from imaging, (4)
developing a capability for advanced space weather prediction with a
lead time of days using measurements of solar energetic particles and
magnetic fields simultaneously from both sides of the Sun. An extended,
4pi mission with additional spacecraft above the solar poles (solar
sail required) will allow the viewing of the entire solar globe. This
will combine the solar polar mission science goals (meridional flows,
polar magnetic fields) with those of the above minimal mission, plus
affording new synergistic opportunities such as interplay between active
regions (latitude <45deg ) and polar structures (latitude >45deg
) and 3-D imaging of CMEs. Suggested instrumentation includes a
Doppler-magnetograph for photospheric imaging, particle detectors and a
magnetometer for in-situ measurements, and a two-frequency radio system
(X and Ka bands) for communication and coronal sounding. Unique aspects
and advantages of the concept for the NASA Road Map are discussed.
---------------------------------------------------------
Title: Anomalous Diffusion of Solar Magnetic Elements
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
1999AAS...194.5506C Altcode: 1999BAAS...31..911C
The diffusion properties of photospheric bright points associated with
magnetic elements (MBP's) in the granulation network are analyzed. We
find that the transport is subdiffusive for times less than 20 minutes
but normal for times larger than 25 minutes. The subdiffusive transport
is caused by the walkers being trapped at stagnation points in the
intercellular pattern. We find that the distribution of waiting times at
the trap sites obeys a truncated Levy type (power law) distribution. The
fractal dimension of the pattern of sites available to the random
walk is less than 2 for the subdiffusive range and tends to 2 in the
normal diffusion range. We show how the continuous time random walk
formalism can give an analytical explanation of the observations. We
simulate this random walk by using a version of a phenomenological
model of renewing cells introduced originally for supergranules by
Simon, Title and Weiss (1995). We find that the traps which cause the
subdiffusive transport arise when the renewed convection cell pattern
is neither fixed nor is it totally uncorrelated from the old pattern
as required in Leighton's model, but in some intermediate state between
these extremes. (Work supported in part by NSF grant ATM-9628882).
---------------------------------------------------------
Title: Scaling Universality Classes and Analysis of Solar Data
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1999AAS...194.9301L Altcode: 1999BAAS...31..988L
Many solar phenomena display a scaling symmetry associated with random
multiplicative cascades. Here a physical measure, initially uniform
on a spatial, temporal, or space-time set, is divided among subsets
according to randomly determined fractions. This division is repeated
on smaller and smaller sub-subsets, so that the resulting measure at
the smallest scale is given at any point by the product of a string of
random fractions comprising its fragmentation history. Such measures
are highly intermittent. They characterize such solar phenomena as the
spatial distribution of magnetic flux in an active region and the time
distribution of global X-ray emission. The probability distribution
functions (PDFs) governing the random fractions fall into universality
classes with robust properties (Hentschel 1994). For example, all
PDFs which allow for zero fractions lead to measures with local peaks
of unlimited strengths which are progressively less and less space
filling. The GOES-2 X-ray data belong to this class, which indicates
the presence of critical behavior associated with flares (Lu &
Hamilton 1991). We investigate a number of time series for the presence
or absence of this property. Multifractals in nature may fall into a
narrow universality class described by just 3 parameters (Schertzer, et
al. 1997). We find that at least some examples of active region magnetic
fields do indeed have the conjectured form. Further, we apply a causal
space-time version of this class of multiplicative cascade processes
to forecasting the evolution of solar velocity fields. This work was
supported in part by NSF grant ATM-9628882. Hentschel, H.G.E. 1994,
Phys. Rev. E, 50, 243. Lu, E.T. & Hamilton, R.J. 1991, ApJ, 380,
L89. Schertzer, D., Lovejoy, S., Schmitt, F., Chigirinskaya, Y. &
Marsan, D. 1997, Fractals, 5, 427.
---------------------------------------------------------
Title: Characteristic Scales of Photospheric Flows and Their Magnetic
and Temperature Markers
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1999ApJ...513..506L Altcode:
We study the characteristic scales of quiet-Sun photospheric velocity
fields along with their temperature and magnetic markers in Doppler
images from the Michelson Doppler Imager aboard the SOHO satellite
(SOHO/MDI) in simultaneous, Doppler, magnetic, and intensity images
from the San Fernando Observatory and in full-disk magnetograms
and an intensity image from National Solar Observatory (Kitt
Peak). Wavelet flatness spectra show that velocity fluctuations are
normally distributed (Gaussian). This is often assumed in stochastic
models of turbulence but had not yet been verified observationally
for the Sun. Temperature fluctuations also are Gaussian distributed,
but magnetic fields are intermittent and are gathered into patterns
related to flow structures. Wavelet basis functions designed to detect
characteristic convection cell-flow topologies in acoustically filtered
SOHO/MDI Doppler images reveal granulation scales of 0.7-2.2 Mm and
supergranulation scales of 28-40 Mm. Mesogranular flows are weakly but
significantly detected in the range 4-8 Mm. The systematic flows account
for only 30% of the image variances at granular and supergranular
scales and much less in between. The main flows for the intermediate
range of 2-15 Mm are self-similar, i.e., chaotic or turbulent.
---------------------------------------------------------
Title: Can We Get the Bottom B?
Authors: Ruzmaikin, Alexander
1999soho....9E..26R Altcode:
Understanding the solar dynamics and the origin of active regions
depends crucially on knowledge of magnetic fields in the convection
zone. According to the SOHO/MDI results (Kosovichev et al. 1997)
the dynamo generates magnetic fields mainly near the bottom of the
convection zone. How can we get there? Some clues are given by dynamo
theories, and modeling of instabilities in the convection zone and
processes which result in the emergence of magnetic flux. Magnetic
fields are believed to be generated in the form of predominantly
azimuthal flux tubes. When the magnetic field strength exceeds some
critical value, MHD instabilities break the azimuthal symmetry and
lead to the formation of magnetic loops emerging as active regions
at the solar photosphere. Simulations of instability and emergence
include buoyancy, rotational, and curvature effects and permit
prediction of some properties of the emerging magnetic loops. An
example is the prediction of the distribution of emerging magnetic
fields in solar longitude. Simulations by Caligari et al. (ApJ, 441,
886, 1995) indicate that the emergence of a certain azimuthal mode of
magnetic field strongly depends on the field strength at the bottom
of the convection zone. Hence identification of the longitudinal
distribution of emerging photospheric magnetic fields can give us
the information about the magnetic field strength at the bottom of the
convection zone. Distinguishing between the modes of emerging field most
probably requires simultaneous magnetic imaging of both sides of the
Sun. Simultaneous Doppler imaging of the photosphere from earthside
and from behind the Sun combined with the time-distance technique
(Duvall et al., Nature, 362, 430, 1993) opens an opportunity to detect
fine structures at the base of the convection zone, such as localized
jets or magnetic-field-aligned temperature perturbations associated
with originating active regions (Ruzmaikin et al. in Synoptic Physics,
ed. by Balasubramaniam and Harvey, 1998).
---------------------------------------------------------
Title: Spatiotemporal Correlations and Turbulent Photospheric Flows
from SOHO/MDI Velocity Data
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.; Walton,
S. R.; Tarbell, T.
1998ApJ...509..918C Altcode:
Time series of high-resolution and full-disk velocity images obtained
with the Michelson Doppler Imager (MDI) instrument on board SOHO
have been used to calculate the spacetime spectrum of photospheric
velocity flow. The effects of different methods for filtering acoustic
oscillations have been carefully studied. It is found that the spectra
show contributions both from organized structures that have their origin
in the convection zone and from the turbulent flow. By considering
time series of different duration and cadence in solar regions with
different line-of-sight projections, it is possible to distinguish the
contributions of the spectra from the two different kinds of flows. The
spectra associated with the turbulent velocity fields obey power laws
characterized by two scaling parameters whose values can be used to
describe the type of diffusion. The first parameter is the spectral
exponent of the spatial correlation function and the second is a
scaling parameter of the time correlation function. Inclusion of the
time parameter is an essential difference between the present work
and other solar studies. Within the confidence limits of the data,
the values of the two parameters indicate that the turbulent part of
the flow in the scale range 16-120 Mm produces superdiffusive transport.
---------------------------------------------------------
Title: Compact Doppler magnetograph
Authors: Ruzmaikin, Alexander; Moynihan, Philip I.; Vaughan, Arthur
H.; Cacciani, Alessandro
1998SPIE.3442..115R Altcode:
We designed a low-cost flight instrument that images the full solar
disk through two narrow band filters at the red nd blue 'wings' of
the solar potassium absorption line. The images are produced on a
1024 X 1024 charge-coupled device with a resolution of 2 arcsec per
pixel. Four filtergrams taken in a very short time at both wings in
the left and right states of circular polarization are used to yield
a Dopplergram and a magnetogram simultaneously. The noise-equivalent
velocity associated with each pixel is less than 3 m/s. The measured
signal is linearly proportional to the velocity in the range +/-
4000 m/s. The range of magnetic fields is from 3 to 3000 Gauss. The
optical system of the instrument is simple and easily aligned. With
a pixel size of 12 micrometers , the effective focal length is 126
cm. A Raleigh resolution limit of 4 arcsec is achieved with a 5-cm
entrance apertures, providing an f/25 focal ratio. The foreoptic is
a two-component telephoto lens serving to limit the overall optical
length to 89 cm or less. The mass of the instrument is 14 kg. the power
required is less than 30 Watts. The Compact Doppler Magnetograph can
be used in space mission with severe mass and power requirements. It
can also be effectively used for ground-based observations: large
telescope, dome or other observatory facilities are not required.
---------------------------------------------------------
Title: On a source of Alfven waves heating the solar corona
Authors: Ruzmaikin, Alexander; Berger, Mitchell A.
1998A&A...337L...9R Altcode:
Studies of the origin of coronal heating and acceleration of the solar
wind invoke high-frequency Alfv{e}n waves. Here we suggest a source
for such waves associated with twisted magnetic loops emerging on
the solar surface and reconnecting with the open field. We identify
the loops with the ephemeral regions (small-scale bipoles) observed
by ground-based instruments and by SOHO. To characterize the loops
we employ the concept of a minimum energy state for topologically
complex fields. Emerging loops release energy relaxing to the minimum
state. Relaxation along the minimum state-due to a competition between
footpoint twisting by photospheric motions and reconnections inside
the loops- releases blinks of energy into the solar atmosphere. We
estimate the power released and the range of wave frequencies.
---------------------------------------------------------
Title: Clustering of Emerging Magnetic Flux
Authors: Ruzmaikin, A.
1998SoPh..181....1R Altcode:
Observations show that newly emerging flux tends to appear on the
solar surface at sites where there is flux already; this results in
clustering of solar activity. Standard dynamo theories do not predict
this effect, and the mean field estimated by the theories is too weak
to emerge at the surface of the Sun at all. Here a solution of the
problem is suggested that involves strong fluctuating fields generated
by the dynamo. The magnetic field emerges at the solar surface when the
total field (the mean field plus fluctuations) exceeds the threshold
for buoyancy. A slowly changing enhancement of the mean field provides
a long-living basis ('hump') for emergence of fluctuating fields. The
enhancements are gradually destroyed by the solar differential rotation,
the stretching time scale of which defines the lifetime of clusters
of activity. A simple 2-dimensional model explaining the appearance
of persistent clusters of emerging flux is presented.
---------------------------------------------------------
Title: Transient solar influence on terrestrial temperature
fluctuations
Authors: Lawrence, J. K.; Ruzmaikin, A. A.
1998GeoRL..25..159L Altcode:
We argue that the 11-year periodic solar cycle input assisted by
intrinsic climatic noise can produce transient correlations between
activity on the Sun and the Earth's temperature. The argument is based
on wavelet analysis of simultaneous, 140-year time series of terrestrial
global temperature and solar activity. It is supported by a simple model
utilizing the concept of “stochastic resonance,” a unique effect of
amplification of a weak, periodic signal by a noisy, nonlinear system.
---------------------------------------------------------
Title: Enhanced Synoptic Observations: A Spacecraft on the Other
Side of the Sun
Authors: Ruzmaikin, A.; Feynman, J.; Harvey, J.; Harvey, K.;
Magsonas Team
1998ASPC..140..553R Altcode: 1998ssp..conf..553R
No abstract at ADS
---------------------------------------------------------
Title: Turbulence in coronal mass ejections
Authors: Ruzmaikin, A.; Feynman, J.; Smith, E. J.
1997JGR...10219753R Altcode:
The magnetic fields measured by the ISEE 3 spacecraft are used to study
MHD turbulence within coronal mass ejections (CMEs). The spectral
indices of the turbulence inside CMEs are compared with spectral
indices found in solar wind undisturbed by CMEs. Irrespective of
the CME velocities, the spectra within CMEs are found to differ from
those determined for the fast solar wind from coronal holes. Instead,
the CME spectra more closely resemble those found in the slow solar
wind. Since both CMEs and the plasma sheet are associated with closed
magnetic structures in the solar corona, it appears that the turbulence
in the solar wind arising from closed coronal regions is fundamentally
different from the turbulence in wind from coronal holes. Helical
properties of magnetic fields within CMEs at different scales are
studied. Preliminary results indicate that, in small scales, helical
fields are distributed in a random fashion with alternating signs of
twisting structures. In addition however, CMEs have largescale helical
structures. In the case of the magnetic cloud of day 302, 1978 this
structure is interpreted as a part of the helical structure identified
previously by fitting the data to a force-free flux rope configuration.
---------------------------------------------------------
Title: A model of diffusion produced by a cellular surface flow
Authors: Ruzmaikin, Alexander; Molchanov, Stanislav A.
1997SoPh..173..223R Altcode:
A model of diffusion induced by the joint action of random cells of two
different sizes (granulation and supergranulation) is developed. The
basic properties of the model are defined by the dimensionless ratio
ζ = (the life time)/(characteristic size/velocity) constructed for
these two types of cells. An analytical expression for the diffusivity
as a function of ζ is derived. It is estimated that for the standard
parameters used the contribution of granulation to the joint diffusion
is small. A comparison between the model and numerical simulations of
the kinematic diffusion of magnetic fields on the solar surface is made.
---------------------------------------------------------
Title: Scale Dependence of Photospheric Magnetic, Velocity and
Temperature Structure
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1997SPD....28.0247L Altcode: 1997BAAS...29..901L
Time series fluctuations may show different structure when observed
at different time scale resolutions. Thus, wavelet analysis reveals
that fluctuations in the International Sunspot Number are intermittent
(that is, distributed with kurtosis K>0) on scales less than 2 yr,
but truncated (K<0) on time scales between 2-8 yr. Terrestrial
temperature fluctuations are normally distributed (K=0) over discrete
timescale bands (<1 yr, 4-6 yr, 13 yr) interspersed by regimes of
intermittence (1-4 yr) and truncation (6-13 yr). Similar effects occur
for spatial phenomena. We employ various continuous, two-dimensional
wavelets to analyze digital solar images in Cartesian projection
(simultaneous, co-registered San Fernando Observatory magnetic,
Doppler and continuum images; SOHO/MDI high resolution Doppler images)
and full-disk images in hemispheric projection (KPNO magnetograms,
SOHO/MDI Doppler images). The temperature and velocity data are normally
distributed at all scales up to 64 arc sec, though the temperature
gradients are slightly intermittent (K~1). The magnetic data are mostly
intermittent. Wavelet power spectra for KPNO full-disk magnetograms
are quite featureless and indicate scale invariance of the magnetic
structures. Structural spectra of both active and quiet sun images,
however, show a strong peak in intermittence at a scale near 8 arc
sec. Wavelet analysis permits localization of structures in space as
well as in spatial scale. The highly intermittent structures can be
mapped and are found to be located not in active regions but in some,
though not all, areas of low magnetic activity. We discuss possible
physical relationships among the magnetic, velocity and temperature
distributions studied.
---------------------------------------------------------
Title: Decorrelation Time of Fourier modes in the Spectrum of Solar
Background Velocity Fields
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
1997SPD....28.0261C Altcode: 1997BAAS...29..904C
We calculate the power-energy spectrum of time series of SOHO/MDI
line-of sight high resolution Doppler images near disk center. While the
spatial spectrum presents velocity features at characteristic scales and
not a cascade in wavenumber space, we investigate the extent to which
it is still possible to describe in terms of a scaling exponent the
properties of the decorrelation time for each Fourier mode as a function
of wavelength. We explore the sensitivity of the result to different
methods for removing the contribution of the p-modes to the spectrum.
---------------------------------------------------------
Title: On the origin of sunspots.
Authors: Ruzmaikin, A.
1997A&A...319L..13R Altcode:
It is proposed that sunspots (and other flux emergence phenomena)
originate due to the presence of fluctuating magnetic fields in addition
to the regular, mean field in the convection zone. The mean field
predicted by dynamo theories is too weak by itself to emerge at the
surface of the Sun. However, the same dynamo processes that produce the
mean field also produce fluctuating fields. It is suggested here that
magnetic fields emerge at the solar surface at those random times and
places when the total magnetic field (mean field plus fluctuations)
exceeds the threshold for buoyancy. In this way the mean field is
responsible for observed regularities of the sunspot magnetic fields,
such as the Hale's law and the 11-year periodicity, and the fluctuations
are responsible for emergence of the magnetic field of individual
sunspots. A simple illustrative model calculation of a series of
"sunspot cycles" is presented. The model spectrum compares well with
the observed spectrum of sunspots.
---------------------------------------------------------
Title: Wavelet analysis of the structure of microstreams in the
polar solar wind
Authors: Neugebauer, M.; Ruzmaikin, A.; McComas, D. J.
1997AIPC..385...41N Altcode: 1997recs.conf...41N
The fluctuations in solar-wind velocity measured by the Ulysses
spacecraft above the polar regions of the Sun are organized
into structures called microstreams. The application of wavelet
transformations to the Ulysses data reveals the scales and positions of
the microstreams and their association with variations in the helium
content of the solar wind. It is concluded that the microstreams must
have their origin in solar structures associated with the acceleration
of the solar wind with little modification resulting from interplanetary
phenomena.
---------------------------------------------------------
Title: Wavelet and Multifractal Analyses of Spatial and Temporal
Solar Activity Variations
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1997scma.conf..421L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Spacecraft Going Behind the Sun Will Support SOHO
Authors: Ruzmaikin, A.; Anderson, J. D.; Asmar, S.; Bird, M.; Cassiani,
A.; Coles, W.; Feynman, J.; Harvey, J.; Harvey, K.; Hollweg, J.;
Linker, K.; Mikic, Z.; Pätzold, M.; Smith, E. J.
1997ESASP.404..653R Altcode: 1997cswn.conf..653R
No abstract at ADS
---------------------------------------------------------
Title: Spectral Properties of Solar Convection and Diffusion
Authors: Ruzmaikin, A. A.; Cadavid, A. C.; Chapman, G. A.; Lawrence,
J. K.; Walton, S. R.
1996ApJ...471.1022R Altcode:
We present the results of a study of the scaling properties of
solar photo spheric motions. We use time series of Doppler images
obtained in good seeing conditions with the San Fernando Observatory
28 cm vacuum telescope and vacuum spectroheliograph in video
spectra-spectroheliograph mode. Sixty line-of- sight Doppler images of
an area of the quiet Sun near disk center are investigated. They were
taken at 60 s intervals over a 1 hr time span at ∼2" resolution. <P
/>After filtering to remove 5 minute acoustic oscillations, the
time-spatial spectrum of the velocity is calculated. To study the
turbulence of photospheric flows in the mesogranulation scale range,
we estimate two scaling parameters in the spectrum: the exponent of
the spatial part of the power spectrum and the exponent governing the
scaling of time correlations of each spatial mode. These parameters
characterize the type of diffusion involved and the fractal dimension of
the diffusion front. Our results indicate that the turbulent diffusion
produced by motions in this scale range is not normal diffusion but
superdiffusion.
---------------------------------------------------------
Title: Redistribution of magnetic helicity at the Sun
Authors: Ruzmaikin, A. A.
1996GeoRL..23.2649R Altcode:
Evolution of magnetic loops associated with filaments and coronal mass
ejections involves a redistribution of solar magnetic helicity. Two
mechanisms of the helicity redistribution are discussed. The first
one involves magnetic reconnections among magnetic loops and can
introduce helicity into an erupting magnetic field accompanied with
an encapture of helicity by the Sun. The second one involves the MHD
helicity redistribution in the Sun and indicates that the magnetic
helicity of each hemisphere of the Sun oscillates about a mean with
the half-period of the solar cycle (11 years), but does not change
sign from one 11 year period to the next.
---------------------------------------------------------
Title: On the Multifractal Distribution of Solar Magnetic Fields:
Erratum
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1996ApJ...467..473L Altcode:
Many studies have pointed out fractal and multifractal properties of
photospheric magnetic fields, but placing the various approaches into
context has proved difficult. Although fractal quantities are defined
mathematically in the asymptotic limit of infinite resolution, real
data cannot approach this limit. Instead, one must compute fractal
dimensions or multifractal spectra within a limited range at finite
scales. The consequent effects of this are explored by calculation
of fractal quantities in finite images generated from analytically
known measures and also from solar data. We find that theorems relating
asymptotic quantities need not hold for their finite counterparts, that
different definitions of fractal dimension that merge asymptotically
give different values at finite scales, and that apparently elementary
calculations of dimensions of simple fractals can lead to incorrect
results. We examine the limits of accuracy of multifractal spectra from
finite data and point out that a recent criticism of one approach to
such problems is incorrect.
---------------------------------------------------------
Title: On the Multifractal Distribution of Solar Magnetic Fields
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1996ApJ...465..425L Altcode:
Many studies have pointed out fractal and multifractal properties of
photospheric magnetic fields, but placing the various approaches into
context has proved difficult. Although fractal quantities are defined
mathematically in the asymptotic limit of infinite resolution, real
data cannot approach this limit. Instead, one must compute fractal
dimensions or multifractal spectra within a limited range at finite
scales. The consequent effects of this are explored by calculation
of fractal quantities in finite images generated from analytically
known measures and also from solar data. We find that theorems relating
asymptotic quantities need not hold for their finite counterparts, that
different definitions of fractal dimension that merge asymptotically
give different values at finite scales, and that apparently elementary
calculations of dimensions of simple fractals can lead to incorrect
results. We examine the limits of accuracy of multifractal spectra from
finite data and point out that a recent criticism of one approach to
such problems is incorrect.
---------------------------------------------------------
Title: On the origin of the 1/f spectrum of fluctuations in the
solar wind
Authors: Ruzmaikin, A. A.; Goldstein, B. E.; Smith, E. J.; Balogh, A.
1996AIPC..382..225R Altcode:
The origin of the 1/f low-frequency spectrum of fluctuations observed
in the solar wind is discussed. It is suggested that this spectrum
arises due to sampling random perturbations produced at the Sun. The
perturbation process is characterized by a power-law distribution. It
is pointed out that, due to solar rotation, the sampling is equivalent
to scanning across different size scales on the Sun. The limits of
the spectrum found from the observations are used to estimate the
characteristic scales on the Sun, the scales related to the origin of
the solar wind.
---------------------------------------------------------
Title: Radial evolution of the high/low frequency breakpoint in
magnetic field spectra
Authors: Feynman, J.; Ruzmaikin, A. A.; Smith, E. J.
1996AIPC..382..347F Altcode:
Power spectra of magnetic field variations show different behavior
in two frequency regions; a high frequency region (f<SUP>-5/3</SUP>)
and a low frequency region (f<SUP>-1</SUP>). A clue to the relationship
between them is in the behavior of the breakpoint between the spectral
regions. Statistical studies of the average behavior of spectra
between 0.3 AU and 22 AU have shown that the breakpoint occurs at lower
frequencies with larger heliocentric distances. Ideally the behavior of
the breakpoint in a particular parcel of solar wind should be studied as
that parcel propagates to larger heliocentric distances. The possibility
of carrying out such a study is provided by the fact that in 1974 IMP
8 (1.0 AU), Pioneer 10 (4.3 AU) and Pioneer 11 (5.6 AU) were close
to being coaligned. We compare the breakpoint observed at Earth with
that observed at Pioneers 10 and 11 for closely matched samples of the
wind and find good agreement with a model in which the high frequency
spectrum develops in interplanetary space through a cascade from the
low frequency spectrum.
---------------------------------------------------------
Title: Spectral Properties of the Solar Background Velocity Field
Authors: Cadavid, A. C.; Chapman, G. A.; Lawrence, J. K.; Ruzmaikin,
A. A.; Walton, S. R.
1996AAS...188.3506C Altcode: 1996BAAS...28Q.872C
We study the scaling properties of time series of Doppler images
obtained in good seeing conditions with the San Fernando Observatory
28 cm vacuum telescope and vacuum spectroheliograph in video
spectra-spectroheliograph mode. The images correspond to two areas
of quiet Sun near disk center taken at 60 second intervals from one
hour to six hour spans at ~ 2 arcsec resolution. After removal of 5
min acoustic oscillations the time-spatial spectrum of the velocity is
calculated. To study the turbulence of photospheric flows we estimate
two scaling parameters: the exponent of the spatial part of the power
spectrum and the exponent governing the scaling of time correlations
of each spatial mode. The implied diffusive behavior produced by the
solar convection in the mesogranulation scale range is discussed. This
includes characterization of the type of diffusion involved and the
fractal dimension of the diffusion front.
---------------------------------------------------------
Title: Magnetic field asymptotics in a well conducting fluid
Authors: Dobrokhotov, Sergei; Olive, Victor M.; Ruzmaikin, Alexander;
Shafarevich, Andrei
1996GApFD..82..255D Altcode:
An asymptotic solution of the magnetic induction equation in a
given velocity field is constructed for large magnetic Reynolds
numbers. Initially localized distributions of the magnetic field
are considered. The leading term of the asymptotics is found. The
expansions are proved to be rigorously valid over a finite time
interval. Estimates for the residuals are given. The results are
illustrated by some examples: the Hubble flow with a linear dependence
of the velocity on coordinates, and ABC type flows. The solutions in
these cases are expressed in terms of elementary functions.
---------------------------------------------------------
Title: Turbulent and Chaotic Dynamics Underlying Solar Magnetic
Variability
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1995ApJ...455..366L Altcode:
We examine the temporal scaling properties of solar magnetic activity
on timescales from days to decades. Because of more than 63,000
usable data points, we concentrate on the daily International Sunspot
Number. Some results have been checked with other data sets, primarily
the 10.7 cm microwave flux with about 16,000 data points. Such time
series provide a measure whose scaling and intermittency properties
are analyzed. <P />By means of correlation analysis and both Fourier
and wavelet spectral analysis, we distinguish two regimes of temporal
behavior of the magnetic variability. The scaling of the time series is
analyzed in terms of multiplicative cascade processes which prove to
be invariant over more than two decades of scale from about 2 yr down
to about 2 days or less. We interpret this result to indicate generic
turbulent structuring of the magnetic fields as they rise through the
convection zone. We find that a low-dimensional, chaotic behavior in the
sunspot number operates entirely at timescales longer than a transition
threshold scale of about 8 yr. Magnetic variability on timescales
between 2 yr and 8 yr apparently requires handling by direct simulation.
---------------------------------------------------------
Title: Features of the Solar Background Velocity Field
Authors: Ruzmaikin, A.; Cadavid, C.; Chanpman, G.; Lawrence, J.;
Walton, S.
1995ESASP.376b.249R Altcode: 1995help.confP.249R; 1995soho....2..249R
No abstract at ADS
---------------------------------------------------------
Title: On the origin of 1/f spectrum of magnetic fluctuations in
the solar wind
Authors: Ruzmaikin, A.; Goldstein, B. E.; Smith, E. J.; Balough, A.
1995sowi.conf...38R Altcode:
Spacecraft measurements show that the spectrum of magnetic fluctuations
in the solar wind can be divided into low- and high frequency
parts. The low and high frequency parts are approximately self-similar
(follow a power-law) but with different spectral exponents. (There
is, in addition, a very low frequency range in which the spectrum
is dominated by structures coming directly from the Sun and it is
not self-similar.) For the wind coming from the south polar hole
the boundary between the low- and high frequency parts is at about
1 hour near 1 AU. The observed exponent of the low-frequency part
is approximately -1 . The high frequency spectrum is steeper with
an exponent of about -5/3 . The high frequency spectrum is commonly
believed to be the result of non-linear interactions of magnetic and
velocity perturbations which lead to a turbulent cascade. However,
for the low frequency fluctuations, the site of origin (on the Sun,
in the solar corona or in the solar wind?) and mechanism of generation
remain basically unknown. In this paper we consider the origin of the
1/f spectrum. The analysis of Ulysses data is compared with analysis
of Helios data and the results are used to confront possible models
of origin of the spectrum.
---------------------------------------------------------
Title: Radial evolution of the high/low frequency breakpoint in
magnetic field spectra
Authors: Feynman, J.; Ruzmaikin, A.; Smith, E. J.
1995sowi.conf...80F Altcode:
The spectra of magnetic field variations in the solar wind show
different behavior in two frequency regions; a high frequency region in
which the spectral exponent is about -5/3 and a low frequency region
in which it is typically -1. The two types of variations must arise
from different processes and a clue to the relationship between the
spectral regions lies in understanding the behavior of the breakpoint
between the spectral regions. Studies of the average behavior of
spectra have shown that the break point occurs at about 3.5 hours
at 1 AU. It is also known that, on average, the breakpoint occurs at
lower frequencies with larger heliocentric distances. Ideally however,
instead of the average properties of the spectra, we would like to
know how the breakpoint evolves in particular samples of the solar
wind as they propagate to larger heliocentric distances. In the study
reported here we take advantage of the fact that, in 1974, Pioneer 10
(4.4 AU) and Pioneer 11 (5.6 AU) were close to being co-aligned and
being aligned with the Earth. Solar wind observed at Earth can be
closely matched with solar wind later observed at P10 and P11. We
here compare the breakpoint observed at Earth with that observed at
Pioneers 10 and 11 for matched samples of the wind.
---------------------------------------------------------
Title: Magnitude of the dynamo-generated magnetic field in solar-type
convective zones.
Authors: Kleeorin, N.; Rogachevskii, I.; Ruzmaikin, A.
1995A&A...297..159K Altcode:
Using a nonlinear dynamo model (in a single-mode approximation),
an analytical expression is derived which gives the magnitude of the
mean magnetic field as a function of rotation and other parameters
for a solar-type convective zone. By means of this expression we
find a power-law relation between the X-ray luminosity and stellar
rotation. The exponent in this relation is in agreement with
observations.
---------------------------------------------------------
Title: Turbulence and Chaos in Solar Variability
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
1995SPD....26..514C Altcode: 1995BAAS...27..960C
No abstract at ADS
---------------------------------------------------------
Title: Intermittent turbulence in solar wind from the south polar hole
Authors: Ruzmaikin, A. A.; Feynman, J.; Goldstein, B. E.; Smith,
E. J.; Balogh, A.
1995JGR...100.3395R Altcode:
The magnetic fields measured by the Ulysses spacecraft are used to
study solar wind turbulence in the fast solar wind from the south
polar hole. The spacecraft was at about 46 deg south latitude and
3.9 AU. For a magnetic field with a Gaussian distribution the power
spectrum (second-order structure function) is sufficient to completely
characterize the turbulence. However, the actual distribution is
non-Gaussian so that the effects of intermittency must be taken
into account. The observed spectral exponents include effects of
intermittency and cannot be directly compared with the standard
second-order spectral theories such as the Kolmogorov and Kraichnan
theories. To permit a better comparison of the observations with the
theoretical models, we study the structure characteristics of the
data. We find the exponents of the second-order structure functions
(power spectra) and the higher-order normalized structure functions
for the components of the magnetic fields. We show that these sets of
exponents can be approximately described by two basic numbers: the
spectral exponent and the intermittency exponent. The intermittency
exponent characterizes correlation properties of the energy cascade
from large to small scales. Before comparing the observations to the
theoretically expected values, a reduction must be made to the observed
spectral exponent. The amount of the reduction depends on both the
intermittency exponent and the model of the energy cascade assumed in
the turbulence theory. We reduce the measured spectral indices according
to a simple model for Alfvén turbulence that is described here. We
then compare our reduced spectral indices with second-order spectral
theory. The reduced spectral indices for the period range of 1 min to
about a half hour are remarkably constant and in good agreement with
the value of 3/2. Thus our treatment is self-consistent. Our tentative
conclusion is that the high-frequency turbulence appears to agree with
the model of random-phased Alfvén waves. This tentative conclusion
must be tested by further theoretical and observational work.
---------------------------------------------------------
Title: Multiplicative cascade models of multifractal solar magnetic
fields
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1995PhRvE..51..316L Altcode:
We present a multifractal analysis of digital, photoelectric images
of line-of-sight magnetic fields in solar active regions and quiet
photosphere. We study a positive definite measure related to the Ohmic
dissipation of magnetic energy. After calculation of the multifractal
spectrum directly and by scaling of the moments of the measure, we
focus on a multiplicative cascade approach. We infer a scale-invariant
rule by which the Ohmic dissipation measure is allocated among subsets
of its support through a hierarchy of scales. Knowledge of this rule,
which is hampered to some extent by image noise, permits the calculation
of the multifractal spectrum to great accuracy. The scaling of the
solar dissipation field resembles that of fully developed turbulence
in an atmospheric boundary layer. The cascade multiplier probability
distribution is itself a very useful quantity. It allows a convenient
display of image properties, such as self-similarity. Further, it is
more closely related than the multifractal spectrum to the physics
of the turbulent field evolution, and it thus can be used to impose
stronger constraints on turbulent dynamo models of magnetic field
generation.
---------------------------------------------------------
Title: Spectra of Solar Magnetic Fields and Diffusion
Authors: Ruzmaikin, A. A.; Cadavid, A. C.; Chapman, G. A.; Lawrence,
J. K.; Walton, S. R.
1995ASPC...76..292R Altcode: 1995gong.conf..292R
No abstract at ADS
---------------------------------------------------------
Title: Scaling of Solar Magnetic Fields
Authors: Ruzmaikin, A.; Cadavid, C.; Lawrence, J.; Rabin, D.; Lin,
H. -S.
1995itsa.conf..375R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar irradiance variations and nonlinear mean field dynamo
Authors: Kleeorin, N.; Rogachevskii, I.; Ruzmaikin, A.
1994SoPh..155..223K Altcode:
By using a nonlinear model of an axisymmetricα - Ω dynamo, an
analytical expression which gives the magnitude of the mean magnetic
field as a function of rotation and other parameters for a solar-type
convective zone is obtained. The mean magnetic field varies as the
power of the rotation rate. The resulting theoretical relationship
of the X-ray luminosity as a function of the angular velocity is in
agreement with observations by Fleming, Gioia, and Maccacaro (1989).
---------------------------------------------------------
Title: Distribution of the interplanetary magnetic field revisited
Authors: Feynman, Joan; Ruzmaikin, Alexander
1994JGR....9917645F Altcode:
The adequacy of the power spectrum to characterize the variations of
a parameter depends on whether or not the parameter has a Gaussian
distribution. We here perform very simple tests of Gaussianity on the
distributions of the magnitudes of the interplanetary magnetic field,
and on the distributions of the components; that is, we find the
first four cumulants of the distributions (mean, variance, skewness,
and kurtosis) and their solar cycle variations. We find, consistent
with other recent analyses, that the traditional distributions of the
1-hour averaged magnitude are not distributed normally or lognormally
as has often been assumed and the 1-hour averaged z component is found
to have a nonzero kurtosis. Thus the power spectrum is insufficient to
completely characterize these variations and polyspectra are needed. We
have isolated variations in the 1/f frequency region of the spectrum
and show that the distributions of the magnitudes have nonzero skewness
and kurtosis, the magnitudes are not distributed lognormally, and the
distributions of the components have nonzero kurtosis. Thus higher-order
spectra are again needed for a full characterization.
---------------------------------------------------------
Title: Multifractal Models of Small-Scale Solar Magnetic Fields
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.;
Kayleng-Knight, A.
1994ApJ...429..391C Altcode:
We generate, both analytically and numerically, artifical,
two-dimensional images composed of a known self-similar, and thus
multifractal measured with added Gaussian white noise. These are
used to interpret observed, line-of-sight, solar magnetic field
distributions noisy multifractals. The range of self-similar scaling of
observed, distributions is extended beyond that of previous work. Our
interpretation of the data is then used to confront theoretical models
for the generation of small-scale solar magnetic fields. We investigate
the multifractial structure of the field generated by two-dimensional,
random cell dynamos and find that self-similarity is relatively enhanced
for more intermittent distributions and strong correlations between
cells. An optimum value of the intercellular diffusion coefficient
maximizes the degree of intermittency. The simulated field from
a linear, kinematic, fast dynamo with two-dimensional, chaotic,
'ABC' flow displays scaling properties resembling those of observed
solar fields. We suggest that the chaotic element of this model is
the crucial ingredient for the long-range correlations that lead to
multifractal scaling.
---------------------------------------------------------
Title: Long-term persistence of solar activity
Authors: Ruzmaikin, Alexander; Feynman, Joan; Robinson, Paul
1994SoPh..152..313R Altcode: 1994IAUCo.143..313R; 1994svs..coll..313R
The solar irradiante has been found to change by 0.1% over the recent
solar cycle. A change of irradiante of about 0.5% is required to
effect the Earth's climate. How frequently can a variation of this
size be expected?
---------------------------------------------------------
Title: Long-term persistence of solar activity
Authors: Ruzmaikin, Alexander; Feynman, Joan; Robinson, Paul
1994SoPh..149..395R Altcode:
We examine the question of whether or not the non-periodic variations
in solar activity are caused by a white-noise, random process. The
Hurst exponent, which characterizes the persistence of a time series,
is evaluated for the series of<SUP>14</SUP>C data for the time interval
from about 6000 BC to 1950 AD. We find a constant Hurst exponent,
suggesting that solar activity in the frequency range from 100 to
3000 years includes an important continuum component in addition to
the well-known periodic variations. The value we calculate,H ≈ 0.8,
is significantly larger than the value of 0.5 that would correspond
to variations produced by a white-noise process. This value is in
good agreement with the results for the monthly sunspot data reported
elsewhere, indicating that the physics that produces the continuum is
a correlated random process and that it is the same type of process
over a wide range of time interval lengths.
---------------------------------------------------------
Title: Scaling properties of photospheric magnetic fields
Authors: Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
1994ASIC..433..279L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Multifractal Measure of the Solar Magnetic Field
Authors: Lawrence, J. K.; Ruzmaikin, A. A.; Cadavid, A. C.
1993ApJ...417..805L Altcode:
We analyze high-resolution, digital, photoelectric images of solar
photospheric magnetic fields. The line-of-sight fields are found to
scale in a self-similar way with resolution and thus can be expressed
in the form of a signed multifractal measure. The scaling properties of
the measure are used to extrapolate field integrals, such as moments of
the magnetic field, below resolvable limits. The scaling of the field
moments is characteristic of highly intermittent fields. We suggest
that the quiet-Sun photospheric fields are generated by local dynamo
action based on random convective motions at high magnetic Reynolds
number. The properties of active region images are determined by the
presence of fields generated by the global, mean field dynamo.
---------------------------------------------------------
Title: The spectrum of the interplanetary magnetic field near 1.3 AU
Authors: Ruzmaikin, Alexander; Lyannaya, I. P.; Styashkin, Valerij A.;
Eroshenko, E.
1993JGR....9813303R Altcode:
A time series of the interplanetary magnetic field measured near 1.3
AU by Phobos 2 is analyzed as a fractal. The fractal dimension of
the curves corresponding to the components and to the strength of the
magnetic field are found to be close to 5/3. The corresponding spatial
spectra are interpreted in the framework of MHD turbulence.
---------------------------------------------------------
Title: Self-Similarity in Solar Magnetic Images
Authors: Lawrence, J. K.; Ruzmaikin, A. A.; Cadavid, A. C.
1993BAAS...25.1219L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Multiscale Measure of the Solar Magnetic Field
Authors: Ruzmaikin, A. A.; Lawrence, J. K.; Cadavid, A. C.
1993BAAS...25.1219R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Magnetic Fields, Multifractals and Dynamos
Authors: Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.;
Kayleng-Knight, A.
1993BAAS...25R1206C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ekman-Hartmann Boundary Layers and the Length of Day Variations
Authors: Kleeorin, N.; Rogachevskii, I.; Ruzmaikin, A.
1993IAUS..157..453K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Random cell dynamo
Authors: Ruzmaikin, Alexander; Liewer, Paulett C.; Feynman, Joan
1993GApFD..73..163R Altcode:
A simple numerical model of the self-excitation of the magnetic field
by chaotic motion of a highly conductive fluid is being developed. It
is based on the following approach to simulating the turbulent
dynamo generation of magnetic fields: the fluid is divided into
cells and each cell acts as a machine that can randomly amplify or
destroy a given magnetic field. The random amplification models the
effects of a chaotic fast dynamo and the random destruction models
the effects of reconnection. Uncorrelated and correlated processes
are considered. Effects of non-linearity, diffusion, and correlation
between cells in time and space are also included. Numerical results are
presented from one- and two-dimensional models and possible applications
to the generation and spatial-temporal distribution of solar, planetary
and interplanetary magnetic fields are discussed.
---------------------------------------------------------
Title: On the role of rotation of the internal core relative to
the mantle.
Authors: Ruzmaikin, A.
1993spd..conf..265R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic ropes in the solar wind
Authors: Ruzmaikin, Alexander; Shukurov, Anvar; Sokolov, Dmitrii
1992JGR....9715007R Altcode:
The generation of magnetic fluctuations by MHD turbulence in the
solar wind is discussed. An estimate of the effective magnetic
Reynolds number in the solar wind based on a width of the inertial
range of the turbulence is proposed. Dynamo activity is predicted to
lead to generation of magnetic ropes whose length is of the order of
the energy range scale, 2.5×10<SUP>11</SUP> cm, and whose thickness
can be as low as 5×10<SUP>8</SUP> cm. Experimental detection of the
ropes would require determination of two-point and higher correlation
functions for the magnetic fluctuations in the solar wind.
---------------------------------------------------------
Title: Differential rotation of the liquid core of the Earth.
Authors: Nikitina, L. V.; Ruzmaikin, A. A.
1992Ge&Ae..32..140N Altcode:
Conditions for the appearance of anisotropic convection (a possible
cause of the differential rotation of the earth's liquid core) are
examined, and its parameters for the earth's core are determined. The
distribution of the differential rotation is obtained, and the relative
gradient of the angular velocities of the core and the mantle produced
by the anisotropic convection is determined. The magnitude of this
gradient is of the order of 10 exp -6, which is comparable with the
western-drift velocity of the geomagnetic field.
---------------------------------------------------------
Title: Magnetic Intermittency on the Sun
Authors: Ruzmaikin, Alexander
1992ASPC...27..189R Altcode: 1992socy.work..189R
No abstract at ADS
---------------------------------------------------------
Title: On Long-Term Dynamics of the Solar Cycle
Authors: Ruzmaikin, Alexander; Feynman, Joan; Kosacheva, Valentina
1992ASPC...27..547R Altcode: 1992socy.work..547R
No abstract at ADS
---------------------------------------------------------
Title: On the origin of Uranus and Neptune magnetic fields
Authors: Ruzmaikin, A. A.; Starchenko, S. V.
1991Icar...93...82R Altcode:
The Uranus and Neptune magnetic fields discovered by Voyager 2 can be
explained by a dynamo acting in a thin conductive convective shell
existing at the bottom of the icy oceans of the planets. The main
helicity and differential rotation are the source for the dynamo
which effectively excites nonaxisymmetric modes of the mean magnetic
field. Estimates of the magnetic field amplitude in the nonlinear
regime and of the inclination between the magnetic moment and the
rotation axis are given.
---------------------------------------------------------
Title: Measurement of the magnetic field vector from a rotating
spacecraft.
Authors: Trubetskov, M. K.; Eroshenko, E. G.; Liannaia, I. P.;
Ruzmaikin, A. A.; Sokolov, D. D.; Stiazhkin, V. A.; Shukurov, A. M.
1991KosIs..29..597T Altcode: 1991CosRe..29..597T
The authors propose a method of restoration of magnetic field components
measured by a vector magnetometer onboard of a spacecraft which rotates
at an angular velocity unknown in advance. The available magnetometer
data are used for a precise estimation of the spacecraft angular
velocity. The latter estimate, combined with knowledge of the initial
orientation of the spacecraft, allows to restore the components of
the external magnetic field in an inertial frame. The proposed method
is applied to analysis of magnetic field measurements near Mars by
"Phobos 2". The angular velocity of the spacecraft is estimated to an
accuracy higher than 0.1 percent.
---------------------------------------------------------
Title: The Martian dynamo
Authors: Ruzmaikin, Alexander
1991PEPI...67..268R Altcode:
Mars has a well-conducting core composed of a mixture of iron and
sulphur. It is probably liquid and differentially rotating. The main
problem is whether the core is stably stratified or convective. About
10-15% of sulphur is enough to drive a compositional convection over
a great part of Martian evolution if an inner solid solid core was
formed. Convection in a liquid rotating stratified core results in a
mean helicity, which, together with differential rotation and turbulent
magnetic diffusivity, is a source for mean field dynamo. The magnitude
of the magnetic field generated can explain the origin of magnetization
of the shergottie, nakhlite and chassignite meteorites. However,
the dynamo probably does not work at present, in accordance with
a weak large-scale magnetic field on the Martian surface estimated
from the Mars-2, -3, -5, and Phobos mission results. This field is
interpreted as an external product of the magnetized mantle having
a slightly elliptical form. Some other possible explanations for the
outer magnetic field are discussed.
---------------------------------------------------------
Title: Large-scale flows excited by magnetic fields in the solar
convective zone
Authors: Kleeorin, N. I.; Ruzmaikin, A. A.
1991SoPh..131..211K Altcode:
Observations demonstrate a nearly 22-year periodic zonal flow
superimposed on general solar differential rotation (LaBonte and
Howard, 1982) and some meridional motions (e.g., Tuominen, Tuominen,
and Kyrolänen, 1983). Such flows can be excited by the magnetic wave
generated by the dynamo in the solar convective zone.
---------------------------------------------------------
Title: The Toroidal Magnetic Field Inside the Sun
Authors: Krivodubskij, V. N.; Dudorov, A. E.; Ruzmaikin, A. A.;
Ruzmaikina, T. V.
1991LNP...380..187K Altcode: 1991IAUCo.130..187K; 1991sacs.coll..187K
No abstract at ADS
---------------------------------------------------------
Title: Fractal Flux Tubes of the Solar Magnetic Field
Authors: Ruzmaikin, Alexander; Sokoloff, Dmitry; Tarbell, Theodore
1991LNP...380..140R Altcode: 1991IAUCo.130..140R; 1991sacs.coll..140R
The small-scale solar magnetic field exceeding a given threshold forms
a fractal set. A dimension of this fractal is found from magnetograms
with varying linear resolution. The dimension depends on the value
of the threshold magnetic field (multifractality). A simple dynamo
model explaining the origin of the fractal magnetic structure is
considered. The dynamo produces a magnetic field in the form of
flux tubes with a fractal distribution of magnetic field across the
tube. The observed dimension gives a possibility of estimating a degree
of structuredness of the solar velocity field.
---------------------------------------------------------
Title: Magnetic History of the Sun
Authors: Levy, E. H.; Ruzmaikin, A. A.; Ruzmaikina, T. V.
1991suti.conf..589L Altcode:
This review gives a brief overview of the major magnetic effects and
behavior that characterized and influenced aspects of the gross history
of the sun. The chapter surveys the behavior of magnetic fields in
the sun from the early effect of the interstellar field on protosolar
collapse through to the modern solar magnetic cycle. Emphasis is given
to the evolution of the sun's magnetic field, its memory of the past
magnetic states, and its loss of memory, as these depend on physical
episodes, conditions and phenomena during the sun's development.
---------------------------------------------------------
Title: Asymptotic Methods in the Nonlinear Mean-Field Dynamo
Authors: Sokoloff, D. D.; Shukurov, A.; Ruzmaikin, A. A.
1991LNP...380..135S Altcode: 1991IAUCo.130..135S; 1991sacs.coll..135S
We discuss the methods and results of analysis of nonlinear mean-field
dynamo models based on a-quenching in two asymptotic regimes, namely
for weakly and highly supercritical excitation. In the former case the
spatial distribution of the steady-state magnetic field is close to
that given by the neutrally stable eigenfunction of the corresponding
kinematic dynamo. In the latter case the magnetic field distribution
within the main part of the dynamo volume is presumably determined
by the balance between the Lorentz and Coriolis forces while near
the boundaries boundary layers arise in which the field adjusts
itself to the boundary conditions. The asymptotic behaviour of the
highly supercritical aw-dynamos is sensitive to the particular form
of dependence of the mean helicity on magnetic field while 2-dynamos
are less sensitive to this dependence.
---------------------------------------------------------
Title: Azimuthal modes of the geomagnetic field.
Authors: Ruzmaikin, A. A.; Tiurmina, L. O.
1990Ge&Ae..30.1022R Altcode:
The concept of the energy spectrum of azimuthal modes (or m-modes)
is introduced. The latitudinal amplitude distribution of the m-modes
on the earth's surface is determined along with their asymmetry with
respect to the equator; the mode with m greater than 2 is susbtantially
weaker in amplitude than the principal modes, m = 0, 1, 2. A comparison
of radial spectral distributions of the n and m modes indicates that
determinations of the depth of a geomagnetic-field source using the
'white noise' concept are inadequate.
---------------------------------------------------------
Title: Book-Review - the Almighty Chance
Authors: Zeldovich, Y. B.; Ruzmaikin, A. A.; Sokoloff, D. D.
1990Sci...249R.573Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Almighty Chance
Authors: Zeldovich, Y. B.; Ruzmaikin, A. A.; Sokoloff, D. D.
1990Sci...249Q.573Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Radio Carbon Evidence of the Global Stochasticity of Solar
Activity
Authors: Gizzatullina, S. M.; Rukavishnikov, V. D.; Ruzmaikin, A. A.;
Tavastsherna, K. S.
1990SoPh..127..281G Altcode:
An estimate of the dimension of the attractor of the dynamic system
responsible for solar activity is obtained from the time series of
carbon 14 experimental data (4300 BC to 1950 AD). According to this
estimate the attractor is a fractal, in shape close to a 3-torus. The
attractor's trajectories characterizing the evolution of the magnetic
field exhibit irregular long-term behaviour.
---------------------------------------------------------
Title: On Forecasting the Sunspot Numbers
Authors: Kurths, J.; Ruzmaikin, A. A.
1990SoPh..126..407K Altcode:
We have applied a technique recently proposed basing on learning
nonlinear dynamics locally to describe the annual sunspot relative
numbers. It is proved that the number of past points for prediction
should be greater than 4 but less than 10. This rather simple approach
yields in average relatively good results for short-term forecasts
(< 11 yr). Particularly, it predicts that the current cycle no. 22
will reach a very high maximum. However, this approach must be modified
in the vicinity of a grand minimum.
---------------------------------------------------------
Title: Magnetic field in the Andromeda nebula inferred from
polarization observations.
Authors: Ruzmaikin, A.; Sokolov, D.; Shukurov, A.; Beck, R.
1990A&A...230..284R Altcode:
We propose a method of pattern recognition intended primarily to
determine the configuration of large-scale magnetic fields in external
galaxies. Single-frequency polarization observations of M31 are
analyzed, to determine parameters of the large-scale magnetic field
in this galaxy. In the inner part of the magnetic ring in M31, for
7 < r < 10 kpc, deviations of the magnetic field configuration
from axial symmetry are noticeable at the 95% confidence level. The
basic axisymmetric component of the field can be distorted either
by the north-south asymmetry of the disk of M31, revealed earlier
in distributions of other constituents of the interstellar medium,
or by the spiral pattern; other possible explanations of apparent
deviations from axial symmetry are also proposed. In the outer parts
of M31 a purely axisymmetric field distribution is consistent with
the available observational data.
---------------------------------------------------------
Title: Book-Review - Magnetic Fields of Galaxies
Authors: Ruzmaikin, A. A.; Shukurov, A. M.; Sokoloff, D. D.;
Ward-Thompson, D.
1990JBAA..100...42R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The flow in the Earth's interior caused by the mutual rotation
of the mantle and the solid core.
Authors: Nikitina, L. V.; Ruzmaikin, A. A.
1990Ge&Ae..30..127N Altcode:
Differences in the angular velocities of the mantle and the solid
core are found to lead to large-scale flow including differential
rotation and meridional circulation in the density-stratified liquid
outer core. The steady-state differential of angular velocities is
sustained by the balance of moments of external (tidal) forces and
internal viscous and magnetic friction.
---------------------------------------------------------
Title: Order and Chaos in the Solar Cycle
Authors: Ruzmaikin, A. A.
1990IAUS..138..343R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Large-Scale Internal Magnetic Field of the Sun
Authors: Dudorov, A. E.; Krivodubskij, V. N.; Ruzmaikin, A. A.;
Ruzmaikina, T. V.
1990IAUS..138..391D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The almighty chance
Authors: Zeldovich, Ya. B.; Ruzmaikin, A. A.; Sokoloff, D. D.
1990alch.book.....Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Intermittent Magnetic Fields Generated by Turbulence in
Galaxies and Galaxy Clusters
Authors: Sokolov, D. D.; Ruzmaikin, A. A.; Shukurov, A.
1990IAUS..140..499S Altcode:
The turbulence of intracluster gas in galaxy clusters and interstellar
gas in galaxies can act as a dynamo generating chaotic magnetic
fields. These fields are concentrated in ropes. The field strength
within the ropes is close to equipartition with turbulent kinetic
energy. These results favorably agree with high-resolution observations
of the galaxy cluster around Cyg A and correlation analysis of the
Galactic nonthermal background. Ropy magnetic fields in interstellar
gas lead to observable variations of, e.g., the Faraday depth at time
scale of 1 month.
---------------------------------------------------------
Title: Dynamo in Astrophysics
Authors: Ruzmaikin, A. A.
1990IAUS..140...83R Altcode:
The origin of magnetic fields in astrophysical objects is developed
theoretically in a discussion of the fast dynamo. Magnetic fields
are described as being 'frozen,' but the complexity of turbulent
astrophysical flows facilitates the generation of the magnetic
field. The role of the mean magnetic field is considered in terms of
stellar activity cycles as well as large-scale magnetic structures in
spiral galaxies. Specific examples are given for the application of the
notion of 'small-scale', intermittent magnetic fields to clusters of
galaxies. The geometry of the Galactic dynamo is developed in terms
of its mean helicity, as derived from observations of the velocity
field. Plasma hydrodynamical motions are shown to preside in the
inception of magnetic fields in stars and galaxies, and the dynamo
process is theorized to be acting on observed plasmas with high magnetic
Reynolds numbers.
---------------------------------------------------------
Title: Magnetic Intermittency
Authors: Molchanov, S. A.; Ruzmaikin, A. A.; Sokoloff, D. D.
1990nowa.conf....2M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Galactic Dynamo Theory Confronted with Observations
Authors: Krasheninnikova, Iu. S.; Sokolov, D. D.; Ruzmaikin, A. A.;
Shukurov, A.
1990IAUS..140..119K Altcode:
Imprints of kinematic dynamo modes in observations of magnetic
structures are evaluated in terms of theoretical models of galactic
dynamos in axisymmetric disks. Direct comparisons of the theoretical
implications of kinematic modes and observations of spiral galaxies
are effective, but nonlinear effects evident in dynamos are not
included in the description. Galactic dynamo theory can only be
compared to observations in the Milky Way, where the asymptotic model
is confirmed. The properties of linear dynamo models in the global
magnetic configurations of spiral galaxies are examined, and nonlinear
distortions of the linear solutions are identified. It is unclear
whether the large-scale magnetic fields in the solar vicinity of the
Milky Way have reached the steady state or whether the calculated value
is accurate. Nonlinear effects in galactic dynamos are theorized to
be relatively weak.
---------------------------------------------------------
Title: Maximally-efficient-generation approach in the dynamo theory
Authors: Ruzmaikin, Alexander; Shukurov, Anvar; Sokoloff, Dmitry;
Starchenko, Sergey
1990GApFD..52..125R Altcode:
We propose a method of derivation of global asymptotic solutions
of the hydromagnetic dynamo problem at large magnetic Reynolds
number. The procedure reduces to matching the local asymptotic
forms for the magnetic field generated near individual extrema of
generation strength. The basis of the proposed method, named here the
Maximally-Efficient-Generation Approach (MEGA), is the assertion that
properties of global asymptotic solutions of the kinematic dynamo are
determined by the distribution of the generation strength near its
leading extrema and by the number and distribution of the extrema. The
general method is illustrated by the global asymptotic solution of the
2-dynamo problem in a slab. The nature of oscillatory solutions revealed
earlier in numerical simulations and the reasons for the dominance
of even magnetic modes in slab geometry are clarified. Applicability
of the asymptotic solutions at moderate values of the asymptotic
parameter is also discussed. We confirm this applicability using
comparisons with complementary asymptotic expansions and numerical
simulations. In particular, this justifies application of the MEGA
solutions to estimation of the generation threshold.
---------------------------------------------------------
Title: Generation of Cosmic Magnetic Fields
Authors: Ruzmaikin, A. A.
1990ASIC..305..235R Altcode: 1990pphc.conf..235R
The generation of magnetic fields by dynamo action of cosmic
turbulent plasmas is considered. Three levels of the mechanism are
discussed: (1) the mean field behaviour; (2) deviations from the
mean field, i.e. magnetic fluctuations; and (3) the generation and
distribution of random magnetic field in the random flow of a conducting
plasma. Examples of magnetic fields generated in the interiors of Uranus
and Neptune, in the Sun, and in clusters of galaxies are presented.
---------------------------------------------------------
Title: Dimension of geomagnetic attractor from data on length of
day variations
Authors: Malinetskii, G. G.; Potapov, A. B.; Gizzatulina, S. M.;
Ruzmaikin, A. A.; Rukavishnikov, V. D.
1990PEPI...59..170M Altcode:
Six-months averaged data on day length variations for 1656-1984 are
used to obtain a lower bound of the dimension of the attractor of a
dynamic system with the Earth's angular velocity as a variable. The
noise level is estimated from the observations available. It is
suggested that the data can be explained by using models with a few
degrees of freedom. Some problems associated with the analysis of
small data samples to determine the attractor dimension are discussed.
---------------------------------------------------------
Title: The galactic dynamo: Axisymmetric and non-axisymmetric modes
Authors: Krasheninnikova, Yulia; Ruzmaikin, Alexander; Sokoloff,
Dmitry; Shukurov, Anvar
1990GApFD..50..131K Altcode:
We discuss recent developments in the theory of large-scale magnetic
structures in spiral galaxies. In addition to a review of galactic
dynamo models developed for axisymmetric disks of variable thickness,
we consider the possibility of dominance of non-axisymmetric magnetic
modes in disks with weak deviations from axial symmetry. Difficulties of
straightforward numerical simulation of galactic dynamos are discussed
and asymptotic solutions of the dynamo equations relevant for galactic
conditions are considered. Theoretical results are compared with
observational data.
---------------------------------------------------------
Title: Book-Review - Magnetic Fields of Galaxies
Authors: Ruzmaikin, A. A.; Shukurov, A. M.; Sokoloff, D. D.
1989JBAA...99..313R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the origin of secular variations of the Earth's main
magnetic field.
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Shukurov, A. M.
1989Ge&Ae..29.1001R Altcode:
A mechanism is proposed for the excitation of magnetic disturbances
that induce secular geomagnetic variations with characteristic times
of less than 100 years (e.g., 60-year variations). These disturbances
have the form of concentrated flux ropes and loops generated by the
fluctuation-type MHD dynamo in the earth's liquid core. The observed
variations are caused by ropes situated in the 60-km-thick skin layer
near the core-mantle boundary.
---------------------------------------------------------
Title: The dynamo origin of magnetic fields in galaxy clusters.
Authors: Ruzmaikin, Alexander; Sokolov, Dmitrii; Shukurov, Anvar
1989MNRAS.241....1R Altcode:
The authors consider the gneration of magnetic fields by turbulent
motions of intracluster gas in rich galaxy clusters. A qualitative
discussion of the properties of intracluster MHD turbulence, its
spectrum, characteristic scales and velocities, and estimation of
hydrodynamic and magnetic Reynolds numbers is presented. Turbulence
arises in the wakes of galaxies which move transonically through the
gas. Magnetic field is generated at scales below the energy-range
scale of turbulence. The magnetic fields are concentrated within thin
intense ropes which occupy a small fraction of the total volume. The
field strength within the ropes is about 10 μG, as determined by
equipartition with kinetic energy of turbulence, while the rms field
strength within a turbulent cell is as low as 2 μG. The correlation
function of the chaotic magnetic field has a number of characteristic
scales ranging from 20 kpc (the turbulence correlation scale) to
2×10<SUP>-3</SUP>kpc (the skin-layer thickness). The results are in
agreement with observations of magnetic fields in the radiohaloes of
galaxy clusters, in particular with recent observations of Cygnus A.
---------------------------------------------------------
Title: The large-scale internal solar magnetic field
Authors: Dudorov, A. E.; Krivodubskij, V. N.; Ruzmaikina, T. V.;
Ruzmaikin, A. A.
1989AZh....66..809D Altcode:
It is hypothesized that, during the collapse of the protosolar cloud,
the magnetic field intensified. In the center of the just-formed,
nonturbulent sun, the intensity of the magnetic field was 10,000 to 1
million G. If the sun passed through a stage of turbulent convection,
only the field generated by dynamo action would remain. The poloidal
magnetic field at this stage could reach 1000-1,000,000 G, but the
intensity would decrease to 10-1 G during the decay of turbulent
convection. The toroidal magnetic field would remain at 1000-1,000,000
G. It is possible that nonuniform rotation of the radiative region
is related to distortions in the angular velocity in the internal
convective zone due to magnetic tension.
---------------------------------------------------------
Title: The Internal Largescale Magnetic Field of the Sun
Authors: Dudorov, A. E.; Krivodubskii, V. N.; Ruzmaikina, T. V.;
Ruzmaikin, A. A.
1989SvA....33..420D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Negative Magnetic Pressure as a Trigger of Largescale Magnetic
Instability in the Solar Convective Zone
Authors: Kliorin, N. I.; Rogachevskii, I. V.; Ruzmaikin, A. A.
1989SvAL...15..274K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The effect of negative magnetic pressure and the large-scale
magnetic field instability in the solar convective zone
Authors: Kleeorin, N. I.; Rogachevskii, I. V.; Ruzmaikin, A. A.
1989PAZh...15..639K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Configuration of large-scale magnetic fields in spiral
galaxies.
Authors: Krasheninnikova, Iu.; Shukurov, A.; Ruzmaikin, A.; Sokolov, D.
1989A&A...213...19K Altcode:
Within the framework of the thin-disc galactic dynamo model of
Baryshnikova et al. (1987), magnetic lines for the axisymmetric
m = 0 and non-axisymmetric m = 1 dynamo modes are presented. The
calculated pitch angles of magnetic lines in the galaxies M31,
M51, M81, IC 342 and the Milky Way agree with observational
data. Spatial distributions of the Faraday rotation measures produced
by axisymmetric and non-axisymmetric fields and their superpositions
are discussed. Effective generation of the m = 1 dynamo mode in M81
is shown. Distribution of magnetic field in IC 342 is discussed in
detail. It is shown that measurements of pitch angles of magnetic
lines in outer parts of galaxies can be used for estimation of the
ratio of the energy-range scale of interstellar turbulence to the
thickness of the ionized gaseous disc. We discuss possible reasons
of presence of bisymmetric fields among the observed magnetic
structures. Non-axisymmetric distortions of the galactic disc with
azimuthal wave number one result in two effects first, the basic
dynamo mode, remaining axisymmetric at small galactocentric distances,
acquires a m = 1 correction in the outer part of the disc. Second,
the difference between the growth rates of the m = 0 and m = 1 dynamo
modes considerably decreases In contrast, weak perturbations from spiral
arms do not affect growth rates of bisymetric dynamo modes Additional
generation of the azimuthal field by helical turbulence (α^2^-dynamo)
cannot make non-axisymmetric modes prevalent in a thin disc.
---------------------------------------------------------
Title: Generation of large-scale magnetic fields on Uranus and
Neptune by turbulent dynamo mechanism.
Authors: Ruzmaikin, A. A.; Starchenko, S. V.
1989KosIs..27..292R Altcode: 1989CosRe..27..292R
It is shown that the observed magnetic field of Uranus is a vector
sum of fields generated by the turbulent dynamo in the core of the
planet and the thin conducting shell surrounding the core. The large
inclination of the dipole moment to the axis of rotation is connected
with the predominant excitation of an axisymmetric field in the core,
and the predominant excitation of a nonaxisymmetric field in the
conducting shell. A configuration with a small inclination of the
dipole to the axis of rotation is expected for Neptune.
---------------------------------------------------------
Title: A generalized two-disk dynamo model
Authors: Ershov, Sergey V.; Malinetskii, George G.; Ruzmaikin,
Alexander A.
1989GApFD..47..251E Altcode:
A generalized two-disk dynamo model is considered that includes
mechanical friction; this model is intended to simulate in its broad
character the behavior of the geodynamo. Fixed points, limit cycles
and chaotic attractors are located for different input parameters
of the model. The chaotic regimes are of several kinds as are the
"routes to chaos". Several approximate models, helpful for studying
the dynamo are discussed. A number of essential differences from the
well-known Rikitake dynamo are demonstrated.
---------------------------------------------------------
Title: Correlation function and spectrum of solar small-scale
magnetic fields.
Authors: Kliorin, N. I.; Ruzmaikin, A. A.; Sokolov, D. D.
1988KFNT....4...28K Altcode:
Spectrum and time correlation function of a magnetic field generated by
reflectionally invariant short-correlated turbulent flow are found. The
results can be applied to study the correlation features of a solar
small-scale magnetic field independent of the solar cycle.
---------------------------------------------------------
Title: Magnetohydrodynamic effect of differential rotation in a
conducting spherical region
Authors: Brodskii, Iu. A.; Krasheninnikova, Iu. S.; Ruzmaikin, A. A.
1988MagGi.......13B Altcode:
A solution is presented for the problem of the eigenvalues and
eigenfunctions of a magnetic field decreasing at infinity for a
spherically symmetric rotating conducting region. Under conditions
of continuously distributed differential rotation, a nonaxisymmetric
magnetic field is completely displaced from the rotating region in the
limit of strong rotation. However, when changes in the angular rotation
velocity are concentrated near a certain radius, the eigenfunctions are
divided into two groups: internal (localized inside the rotating region)
and external. Thus, under conditions of concentrated differential
rotation, there is always a magnetic field in the rotating region. The
magnetic basis proposed here is important for stellar and planetary
dynamo models.
---------------------------------------------------------
Title: The mean-field kinematic turbulent geodynamo
Authors: Ruzmaikin, A. A.; Starchenko, S. V.
1988Ge&Ae..28..475R Altcode:
A WKB asymptotic method is used to obtain a solution to the kinematic
problem concerning the generation of the large-scale geomagnetic
field. The turbulent-dynamo generation of the mean field due to
differential rotation and helicity is considered. The solution obtained
yields a natural explanation for the small inclination of the dipole
component of the geomagnetic field and the westward drift of magnetic
irregularities (the first nonaxisymmetric field modes).
---------------------------------------------------------
Title: Magnetic Field in the Perseus Arm
Authors: Agafonov, G. I.; Ruzmaikin, A. A.; Sokolov, D. D.
1988SvA....32..268A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Excitation of Non-Axially Symmetric Modes of the Sun's Mean
Magnetic Field
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Starchenko, S. V.
1988SoPh..115....5R Altcode:
The kinematic dynamo equations for the mean magnetic field are solved
with an asymptotic method of the WKB type. The excitation conditions
and main characteristics of the non-axially symmetric modes for
a given distribution of the sources are obtained. Utilization of
the helioseismologic data on the Sun's internal rotation permits an
explanation, within the framework of dynamo theory, of the excitation
of the main non-axially symmetric modes revealed in the Sun's magnetic
field sector structure.
---------------------------------------------------------
Title: Magnetic field origin in astrophysical jets
Authors: Gvaramadze, V. V.; Lominadze, Dzh. G.; Ruzmaikin, A. A.;
Sokolov, D. D.; Shukurov, A. M.
1988AdSpR...8b.621G Altcode: 1988AdSpR...8..621G
We propose and analyze a possible mechanism of amplification and
variations in alignment of magnetic fields in astrophysical jets. We
associate these processes with combined action of helical turbulent
plasma motions and large-scale velocity within a jet which stretch
and distort a seed magnetic field.
---------------------------------------------------------
Title: Turbulent Generation of Magnetic Fields in Astrophysical Jets
Authors: Gvaramadze, V. V.; Lominadze, J. G.; Ruzmaikin, A. A.;
Sokoloff, D. D.; Shukurov, A. M.
1988Ap&SS.140..165G Altcode:
We consider evolution of the regular magnetic field in turbulent
astrophysical jets. The observed lateral expansion of a jet is
approximately described by a linear in coordinates regular velocity
field (the Hubble flow). It is shown that in expanding turbulent
jets with non-vanishing mean helicity of the turbulence temporal
amplification and effective realignment of the regular magnetic field
occurs with the field changing orientation from the transverse to
the longitudinal one along the jet axis. The distance at which the
realiggment occurs depends on parameters of the jet, in particular,
on the power of the central source. Estimates for the jet in a weak
source 3C 31 favourably agree with observations.
---------------------------------------------------------
Title: On the cyclicity and amplitude of the activity of rotating
stars
Authors: Kleeorin, N. I.; Ruzmaikin, A. A.
1988mast.conf..321K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Manifestations of Solar Rotation
Authors: Ruzmaikin, A. A.; Starchenko, S. V.
1987SvA....31..552R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic waves of solar activity.
Authors: Makarov, V. I.; Ruzmaikin, A. A.; Ruzmajkin, A. A.;
Starchenko, S. V.
1987SoPh..111..267M Altcode:
An asymptotic solution of generation equations for the solar mean
magnetic field is given and studied. The variation of rotational angular
velocity with depth is taken from helioseismological data. Average
helicity is prescribed according to the mixing length theory. It is
shown that three dynamo waves of the magnetic field are excited. The
first wave is generated at the surface layer and concentrates at
latitudes of about 60°. Its activity becomes apparent in the poleward
migration of the zone of polar faculae formation. The second more
powerful wave of the field is excited in the center of the convection
zone and its activity shows up in a sunspot cycle. The third wave
which is similar to the first wave, is generated at the bottom of the
convection zone and attenuates towards the surface. Its activity may
appear as a three-fold reversal of the polar magnetic field.
---------------------------------------------------------
Title: Generation of large-scale magnetic fields in spiral galaxies.
Authors: Baryshnikova, Iu.; Shukurov, A.; Ruzmaikin, A.; Sokoloff,
D. D.
1987A&A...177...27B Altcode:
The authors discuss the origin of bisymmetric and ring-like large-scale
magnetic structures in spiral galaxies. They develop further the idea
that bisymmetric structures observed in several galaxies are the result
of the generation of non-axisymmetric large-scale magnetic fields by
the turbulent dynamo mechanism. Observations indicate the ring-like
magnetic structure in M31 and the bisymmetric one in M51. The situation
in the Milky Way is more complicated. Our galaxy's rotation is such
that a non-axisymmetric magnetic field can only be generated here if
the half-thickness of the ionized gaseous disc in the solar vicinity
lies between 540 and 720 pc. Otherwise only axisymmetric fields are
generated. Unfortunately, observations allow a much wider range of
possible disc half-thicknesses, ranging from 400 to 1000 pc. The authors
propose some observational tests for verification of their theory.
---------------------------------------------------------
Title: Self-oscillations of a disk dynamo
Authors: Kliorin, N. I.; Lominadze, Dzh. G.; Ruzmaikin, A. A.;
Chagelishvili, G. D.
1987MagGi........3K Altcode:
The problem of a turbulent dynamo in a thin disk with a simple
nonlinearity is examined analytically. It is shown that a nonlinear
system is characterized by self-oscillations, whereas a linear
solution involves monotonic field growth. If differential rotation is
sufficiently large, the magnetic field amplitude may exceed the equal
distribution level, which may be an important factor in explaining
the observed spectra of accretion disks.
---------------------------------------------------------
Title: Magnetic fields of galaxies.
Authors: Ruzmaikin, A.; Ruzmajkin, A. A.
1987imfo.work...16R Altcode:
A global structure of the mean magnetic field in spiral galaxies is
presented. The discovery of two-spiral or bisymmetric configurations in
M51, M81, M33, NGC 6946 is reported. It is noted that the bisymmetric
magnetic structure can be interpreted as the lowest nonaxisymmetric
mode excited by the dynamo action. The structure of the maximal magnetic
field intensity for a galaxy like M51 is indicated schematically.
---------------------------------------------------------
Title: Magnetic fields of spiral galaxies
Authors: Ruzmaikin, A. A.; Sokoloff, D. D.; Shukurov, A. M.
1986ESASP.251..539R Altcode: 1986plas.work..539R
Observational data and theoretical results on the large-scale
magnetic fields in spiral galaxies are reviewed. Observed variations
of position angle of polarized radio emission over a galaxy image
are discussed. Observational data for our Galaxy are insufficient to
decide whether the galactic magnetic field has circular or bisymmetric
structure. Estimates and numerical calculations show that bisymmetric
magnetic structures observed in many galaxies are the result of
excitation of the lowest non axisymmetric magnetic field mode by the
turbulent dynamo. The growth time for bisymmetric field in M51 is
300 million yr. In contrast, all non axisymmetric modes decay in M31,
in accordance with observations. A source of galactic seed field due
to superposition of magnetic loops ejected by supernovae is proposed.
---------------------------------------------------------
Title: Correlative properties of self-exciting fluctuative magnetic
fields
Authors: Kleeorin, N. I.; Ruzmaikin, A. A.; Sokoloff, D. D.
1986ESASP.251..557K Altcode: 1986plas.work..557K
Correlation function of the magnetic fields excited in a reflectionally
symmetrical shortcorrelated turbulent flow is constructed. It is
based on an asymptotical solution valid at large magnetic Reynolds
numbers R<SUB>m</SUB>. Two magnetic correlation scales appear:
l×R<SUB>m</SUB><SUP>-1/2</SUP> and l×R<SUB>m</SUB><SUP>-1/4</SUP>
in addition to l, where l is a basic scale of the turbulence. The
results are discussed in application to the Sun and Galaxy.
---------------------------------------------------------
Title: Book-Review - Magnetic Fields in Astrophysics
Authors: Zeldovich, Y. B.; Ruzmaikin, A. A.; Sokoloff, D. D.;
Kleczek, J.
1986Ap&SS.120..155Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: - / Partial Distribution of the Mean Total Magnetic Flux
of Sunspots
Authors: Ruzmaikin, A. A.; Tavastsherna, K. S.
1986BSolD..10...78R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Magnetic Fields in Astrophysics
Authors: Zeldovich, Y. B.; Ruzmaikin, A. A.; Sokoloff, D. D.;
Downes, A.
1985Obs...105..213Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Solar Dynamo
Authors: Ruzmaikin, A. A.
1985SoPh..100..125R Altcode:
The basic features of the solar activity mechanism are explained
in terms of the dynamo theory of mean magnetic fields. The field
generation sources are the differential rotation and the mean helicity
of turbulent motions in the convective zone. A nonlinear effect of
the magnetic field upon the mean helicity results in stabilizing the
amplitude of the 22-year oscillations and forming a basic limiting
cycle. When two magnetic modes (with dipole and quadrupole symmetry)
are excited nonlinear beats appear, which may be related to the secular
cycle modulation.
---------------------------------------------------------
Title: Anisotropy of Turbulent Transport in a Convective Layer
Authors: Monin, A. S.; Rakhmanova, N. K.; Ruzmaikin, A. A.
1985Ap&SS.114..157M Altcode:
An estimate for the anisotropy of the turbulent viscositys is
given in a convective layer heated from below and rotating around a
vertical axis. In the case of two-dimensional convection, there is a
stationary regime withs⊇2 regardless of the rotation. In the case
of three-dimensional convection in a slowly rotating layer (with the
Taylor number equal to 1600), nonstationary turbulent regimes take
place withs⊇1.6 forR=2.5×10<SUP>4</SUP> (R is the Rayleigh number)
ands⊇1.2 forR=10<SUP>4</SUP>. The parameters plays an, important
role in the theory of differential rotation of the convective solar
or stellar envelopes. So far, it has been evaluated empirically or
semi-empirically. Some prospects in the development of the theory of
differential rotation are discussed here in terms of the moment theory
of hydrodynamic fields. The relation between this strict approach and
an anisotropic viscosity approximation is considered.
---------------------------------------------------------
Title: Book-Review - Magnetic Fields in Astrophysics
Authors: Zeldovich, Y. B.; Ruzmaikin, A. A.; Sokoloff, D. D.; van
der Hucht, K. A.
1985SSRv...41..400Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Magnetic Fields in Astrophysics
Authors: Zeldovich, Y. B.; Ruzmaikin, A. A.; Sokoloff, D. D.; Martens,
P. C. H.
1985SoPh...98..195Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic field distribution in spiral galaxies.
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Shukurov, A. M.
1985A&A...148..335R Altcode:
The spatial distribution of large-scale magnetic fields in gaseous discs
of spiral galaxies is discussed. The authors propose an asymptotic
method of solution of the kinematic turbulent dynamo equations that
is based on the smallness of the ratio of the disc thickness to
its radius. All generated modes of the large-scale magnetic field
have similar distributions over the vertical coordinate. However,
a great number of modes with different radial behavior are excited
simultaneously. A special attention is paid to comparison of these
results with observations of the magnetic fields of spiral galaxies,
e.g. the Galaxy, M31, IC 342, M81.
---------------------------------------------------------
Title: Book-Review - Magnetic Fields in Astrophysics
Authors: Zeldovich, Y. B.; Ruzmaikin, A. A.; Sokoloff, D. D.;
Mestel, L.
1985Natur.313..606Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Three-dimensional model for generation of the mean solar
magnetic field
Authors: Ivanova, T. S.; Ruzmaikin, A. A.
1985AN....306..177I Altcode:
A three-dimensional (non-axisymmetric) model for the solar mean
magnetic field generation is studied. The sources of generation are the
differential rotation and mean helicity in the convective shell. The
system is described by two equations of the first order in time and
the fourth order in space coordinates. The solution is sought for in
the form of expansion over the spherical functions Y(m)<SUB>n.</SUB>
The modes of different m are separated. A finite-difference scheme
similar to the Peaceman-Rachford scheme is constructed in order to
find coefficients of the expansion depending on the time and radial
coordinates. It is shown that a mode with a smaller azimuthal number m
is primarily excited. The axisymmetric mode m = o describes the 22 year
solar cycle oscillations. The modes of m o have no such periodicity,
they oscillate with a period of rotation of the low boundary of the
solar convective shell. The solutions which are symmetric relative
to the equator plane are excited more easily compared with the
antisymmetrical ones. The results obtained are confronted to the
observational picture of the non-axisymmetric large-scale solar
magnetic fields.
---------------------------------------------------------
Title: Book-Review - Magnetic Fields in Astrophysics
Authors: Zeldovich, Y. B.; Ruzmaikin, A. A.; Sokoloff, D. D.
1984JBAA...95...46Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The nature of the 11-year solar torsional oscillations
Authors: Kliorin, N. I.; Ruzmaikin, A. A.
1984PAZh...10..925K Altcode:
The 22-yr dynamo wave in the global solar magnetic field does
indeed generate the observed 11-yr torsional oscillations. The drift
direction, amplitude, and phase shift of the torsional wave relative
to the magnetic activity all agree with LaBonte and Howard's (1982)
measurements. Superposition of the dipole and quadrupole symmetry modes
produces secular asymmetry in the differential rotation relative to
the solar equator.
---------------------------------------------------------
Title: Non-linear dynamos.
Authors: Ruzmaikin, A. A.
1984ESASP.220...85R Altcode: 1984ESPM....4...85R
The basic large-scale features of solar activity are explained
by dynamo theory in terms of mean-field magnetohydrodynamics. The
helicity dependence on the magnetic field results in stabilization
of the basic 22-year oscillations. The excitation of two modes (of
dipole and quadrupole symmetry) can create non-linear beats which may
explain the secular (60 - 80 years) modulation. The observed torsional
waves can be interpreted as a back action of the dynamo waves on the
differential rotation. The actual variations in solar activity are
non-periodic. There are random recurrent episodes of reduced activity
like the Maunder Minimum. The non-linear dynamo models demonstrating
the oscillatory-chaotic behaviour are discussed.
---------------------------------------------------------
Title: A dynamo theorem
Authors: Molchanov, S. A.; Ruzmaikin, A. A.; Sokolov, D. D.
1984GApFD..30..241M Altcode:
It is shown that the frozen-in magnetic field in a given random
homogeneous flow of an incompressible fluid which is renewed after a
finite characteristic time grows exponentially. The rate-of-growth is
positive in the limit of small magnetic diffusivity and continuous in
the frozen-in condition Vm. The increase of the rates-of-growth for
successive field moments is revealed by the intermittent distribution
of the magnetic field generated. The results are obtained by reducing
the kinematic dynamo problem to the evaluation of the product of a
large number of independent random operators.
---------------------------------------------------------
Title: Magnetic field generation in an anisotropically conducting
fluid
Authors: Ruderman, M. S.; Ruzmaikin, A. A.
1984GApFD..28...77R Altcode:
An example of an exponentially growing magnetic field in a fluid
with shear and a homogeneous but anisotropic magnetic diffusivity is
constructed. An induction equation for an anisotropic fluid is derived
and a solution of the dynamo type in an unbounded fluid is obtained. The
motion with one coordinate bounded is analyzed. A similarity between
the solutions and the known homopolar disk dynamo is noted.
---------------------------------------------------------
Title: Mean maganetic field in renovating random flow
Authors: Dittrich, P.; Molchanov, S. A.; Sokolov, D. D.; Ruzmaikin,
A. A.
1984AN....305..119D Altcode:
An integral equation is derived for a mean magnetic field in a random
velocity field that renovates after a characteristic time τ. It
is shown that in two cases, i.e. when (1) the correlation time
is short, τ very low l/v<SUB>0</SUB> (where l and v<SUB>0</SUB>
are the characteristic scale and velocity), and (2) for long wave
components of the field, k<SUP>-1</SUP> very large v<SUB>0</SUB>τ, the
equation is reduced to the differential one, whose form has first been
given by Steenbeck, Krause and Rädler. Expressions for the equation
coefficients are obtained in the two above cases. In a general case the
integral equation cannot be reduced to the differential one although
its spectral properties are close in a certain sense to those of
the SKR-equation. There are differences, however, that are shown on
the example of the Gaussian distribution of particles moving along
random paths.
---------------------------------------------------------
Title: Kinematic dynamo problem in a linear velocity field
Authors: Zel'dovich, Ya. B.; Ruzmaikin, A. A.; Molchanov, S. A.;
Sokolov, D. D.
1984JFM...144....1Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Turbulent dynamo
Authors: Ruzmaikin, A. A.
1984ntpp.proc..481R Altcode:
A solution of the kinematic dynamo problem for a random renovating flow
modulating a turbulence is presented. A general solution of the Cauchy
problem is first obtained for the exponentially growing solution of
the magnetic field of an incomressible fluid with a constant magnetic
diffusivity. The solution is then used to derive moment equations for
the magnetic field for the case of a short-time correlated velocity
field. Finally, the dynamo theorem is presented, which describes the
magnetic field behavior at R(m) (magnetic Reynolds number) approaching
infinity. It is concluded that the field distribution is nonhomogeneous
in space.
---------------------------------------------------------
Title: Mean Magnetic Field in Renovating Random Flow
Authors: Dittrich, P.; Molchanov, S. A.; Sokoloff, D. D.; Ruzmaikin,
A. A.
1984AN....305Q.119D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Gemittelte magnetische Felder in sich erneuernden
Zufallsströmungen
Authors: Dittrich, P.; Molchanov, S. A.; Sokoloff, D. D.; Ruzmaikin,
A. A.
1984AN....305R.119D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Mean-field dynamo with cubic non-linearity
Authors: Kleeorin, N. I.; Ruzmaikin, A. A.
1984AN....305..265K Altcode:
A turbulent mean-field alpha-omega dynamo model of magnetic-field
generation in astrophysical objects is developed, assuming a quadratic
dependence of the helicity on the magnetic field. The mean-field
equation for cubic nonlinearity is reduced to a system of infinite
equations with coefficients determined by the eigenfunctions and
eigenvalues of the linear problem, and the one-mode and two-mode
approximations are examined in detail. The supercritical solution in the
one-mode approximation is found to be stable for d(gamma)/dD greater
than zero, where gamma is the growth rate of the linear solution and
D is the dynamo number. In the two-mode approximation, the nonlinear
interaction of a dipole mode and a weaker quadrupole mode is used to
derive the conditions for synchronization and beating.
---------------------------------------------------------
Title: The nature of the 11-year solar torsional oscillations
Authors: Kliorin, N. I.; Ruzmaikin, A. A.
1984SvAL...10..390K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Mean-Field Dynamo with Cubic Non-Linearity
Authors: Kleeorin, N. I.; Ruzmaikin, A. A.
1984AN....305R.265K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Mean-Field Dynamo mit kubischer Nichtlinearität
Authors: Kleeorin, N. I.; Ruzmaikin, A. A.
1984AN....305Q.265K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Asymptotic solution of the mean field dynamo problem
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Shukurov, A. M.
1984ntpp.proc..489R Altcode:
An asymptotic solution is found for the turbulent dynamo equation
to describe the evolution of the magnetic field of an astronomical
object. The solution to the problem is based on a quasi-classical
approximation from quantum mechanics. The cases of helical turbulence
and large-scale velocity shear are treated independently. It is found
that the asymptotic solution permits estimates of such parameters
as the growth rate of the mean magnetic field, its configuration,
and the threshold for generation of the magnetic field.
---------------------------------------------------------
Title: A Dynamo Theorem
Authors: Molchanov, S. A.; Ruzmaikin, A. A.; Sokoloff, D. D.
1984GApFD..30..242M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Activity Cycle Periods in Late-Type Stars
Authors: Kleeorin, N. I.; Ruzmaikin, A. A.; Sokolov, D. D.
1983Ap&SS..95..131K Altcode:
Period of magnetic activity versus the stellar angular velocity for
stars of given spectral type having extended convective shells is
estimated within the framework of mean field dynamo theory. The
dependence appears to be not monotonous, and can be checked by
observations.
---------------------------------------------------------
Title: Asymptotic solution of the alpha-squared-dynamo problem
Authors: Sokolov, D.; Shukurov, A.; Ruzmaikin, A.
1983GApFD..25..293S Altcode:
The turbulent dynamo equation with non-uniform mean helicity is
solved in an approximation, which is similar to the quasi-classical
approximation of quantum mechanics. The rate of growth of the
magnetic field is evaluated and a condition for dynamo action is
obtained. The generated magnetic field is concentrated in the vicinity
of an extremum of mean helicity but in general vanishes at the point
of the extremum. The field is asymptotically force-free. The results
obtained here clarify the fact, known from numerical calculations,
that the threshold values of the dynamo-number for excitation of dipole
and quadrupole modes are very close to each other.
---------------------------------------------------------
Title: Non-linear problems of the solar dynamo
Authors: Ruzmaikin, A. A.
1983spm..conf..151R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic fields in astrophysics
Authors: Zeldovich, Ia. B.; Ruzmaikin, A. A.; Sokolov, D. D.
1983flma....3.....Z Altcode:
The evidence of cosmic magnetism is examined, taking into account
the Zeeman effect, beats in atomic transitions, the Hanle effect,
Faraday rotation, gyro-lines, and the strength and scale of magnetic
fields in astrophysics. The origin of magnetic fields is considered
along with dynamos, the conditions for magnetic field generation,
the topology of flows, magnetic fields in stationary flows, kinematic
turbulent dynamos, the turbulent dynamo in a disk, topics in nonlinear
turbulent dynamo theory, stellar cycles, the galaxy and its magnetic
field, the galactic dynamo, the role of magnetic fields in star
formation, magnetic fields in cosmology, accretion on black holes,
and strong magnetic fields. Attention is given to frozen-in magnetic
fields, a relict field hypothesis, the random walk of fluid particles,
the problems of stellar taxonomy, evidence of stellar activity, the
stochastic nature of the prolonged weakening of solar activity, the
evolution of magnetic clouds, pulsars, and the problem of magnetic
charges, referred to as 'monopoles'.
---------------------------------------------------------
Title: Dynamo problems in astrophysics
Authors: Zeldovich, Ia. B.; Ruzmaikin, A. A.
1983ASPRv...2..333Z Altcode:
Some current topics in hydromagnetic dynamo theory are discussed in the
astrophysical context of large magnetic Reynolds number. Criteria are
defined for field generation in a state of near-complete freezing-in. An
account is given of certain qualitative aspects of a turbulent
dynamo operating through nonuniform rotation of a conducting medium
subject to random motions with helicity. Such dynamos might be at
work in planetary cores, stellar envelopes, galaxies, and the gaseous
accretion disks around X-ray sources. The concepts of stochasticity and
strange attractors in a magnetic dynamo are examined, and a qualitative
interpretation is offered for the occasional prolonged interruptions
of the solar activity cycle, such as the Maunder minimum.
---------------------------------------------------------
Title: Spectrum of the Galactic Magnetic Fields
Authors: Ruzmaikin, A. A.; Shukurov, A. M.
1982Ap&SS..82..397R Altcode:
The magnetic fields observed in the galactic disc are generated
by the differential rotation and the helical turbulent motions of
interstellar gas. On the scalesl=2πk <SUP>-1</SUP> which lie in the
intervall <SUB>0</SUB><l<l <SUB> e </SUB> (l <SUB>0</SUB>≃100
pc is the energy-range scale of the galactic turbulence), the spectral
density of the kinetic energy of turbulence (∝k <SUP>-5/3</SUP>)
exceeds the magnetic energy spectral density (∝k <SUP>-1</SUP>). The
equipartition between magnetic and kinetic energies is reached atl=l
<SUB> e </SUB>≃6 pc in the intercloud medium and is maintained down
to the scalel=l <SUB> d </SUB>≃0.03 pc. In dense interstellar cloudsl
<SUB> e </SUB> is determined by the individual cloud size andl <SUB>
d </SUB>≃0.1 pc.The internal turbulent velocities in H i clouds
(cloud size is assumed to be 10 pc) lie in the range from 1.8 to 5.6km
s<SUP>-1</SUP>, fitting well within the observed range of internal rms
velocities. Dissipation of the interstellar MHD turbulence leads to
creation of temperature fluctuations with amplitudes of 150 K and 65 K
in dense clouds and intercloud medium, respectively. The small-scale
fluctuations observed in the interstellar medium may arise from such
perturbations due to the thermal instability, for instance. Dissipation
of the MHD turbulence energy provides nearly half of the energy supply
needed to maintain the thermal balance of the interstellar medium.
---------------------------------------------------------
Title: The magnetic field in mirror-invariant turbulence
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1981PAZh....7..701R Altcode:
Exponential magnetic field growth in a mirror-symmetric (in the mean)
turbulent conducting fluid is shown to be possible. The back action
of the field on the turbulent motion is neglected. The excitation
criterion and spectrum are obtained for small wave numbers.
---------------------------------------------------------
Title: Asymptotic Properties of Disk Dynamo
Authors: Isakov, R. V.; Ruzmaikin, A. A.; Sokolov, D. D.; Faminskaia,
M. V.
1981Ap&SS..80..145I Altcode:
The asymptotic properties of a turbulent disk dynamo at large
dimensionless numbersR <SUB>α</SUB> andR <SUB>ω</SUB> characterizing
the helicity and the differential rotation are analysed. Three types of
generations in the dependence of the relations betweenR <SUB>α</SUB>
andR <SUB>ω</SUB> are found: α<SUP>2</SUP>-dynamo and two types of
αω-dynamo. For each of these types the rates of growth are obtained
and the forms of solution are pointed out. Boundaries of the disk
dynamo approximation are given.
---------------------------------------------------------
Title: Magnetic Field Generation in the Galactic Disk
Authors: Ruzmaikin, A. A.; Shukurov, A. M.
1981SvA....25..553R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic field generation in the galactic disk
Authors: Ruzmaikin, A. A.; Shukurov, A. M.
1981AZh....58..969R Altcode:
A model is developed wherein large-scale magnetic field generation
in the Galaxy is determined by two dimensionless dynamo numbers. This
relationship is examined using the observed rotation curve of the Galaxy
and taking into account the radial variations of the ionized gas layer
thickness and of the characteristic velocity of turbulent motions. It
is found that the (alpha)(omega) dynamo operates in the main body of
the galactic disk, producing an even nonoscillatory azimuthal field
and a quadrupole poloidal field. However, in the innermost part of the
Galaxy, the alpha-squared dynamo may operate, and both oscillatory and
steady fields of both dipole and quadrupole symmetry are possible. The
spatial boundaries of the regions of dynamo action are estimated using
the analytical solutions of thin-disk dynamo equations obtained in
the concentrated helicity approximation. The present model may also
be applied to other spiral galaxies, e.g., M31, M81, and NGC 4594.
---------------------------------------------------------
Title: The Magnetic Field in Mirror-Invariant Turbulence
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1981SvAL....7..388R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The solar cycle as a strange attractor
Authors: Ruzmaikin, A. A.
1981ComAp...9...85R Altcode:
The observed 11-year (or 22-year) cycle is not harmonic; short-term
disturbances and a long-term modulation are clearly noted. The most
impressive fact is a sharp weakening of solar activity in the period
1645-1715 (Maunder's minimum) and possibly in earlier epochs. Nonlinear
dynamo theory is necessary to explain these features of the solar
cycle. Such a theory does not yet exist, but some fragments of a future
theory are discussed in this paper in connection with observational
phenomena. Attention is given to the mechanism of solar activity,
11-year activity, quasi-periodic modulation, and the stochastic nature
of the prolonged weakening of solar activity.
---------------------------------------------------------
Title: Properties of a nonlinear solar dynamo model
Authors: Kleeorin, N. I.; Ruzmaikin, A. A.
1981GApFD..17..281K Altcode:
A simple nonlinear model is developed for the solar dynamo, in which
the real convective spherical shell is approximated by a thin flat
slab, and only the back-reaction of the field B on the helicity is
taken into account by choosing the simple law = (1-B2), where and are
constants, to represent the decrease in generation coefficient with
increasing field strength. Analytic expressions are obtained for the
amplitude of the field oscillation and its period, T, as functions of
the deviation d - dCT of a dynamo number d from its critical value dcr
for regeneration. A symmetry is found for the case of oscillations
of small constant amplitude: B(t+½T)= -B(t). A Landau equation is
obtained that describes the transition to such oscillations.
---------------------------------------------------------
Title: A disk dynamo with concentrated spirality
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Shukurov, A. M.
1980MagGi..16...20R Altcode:
The paper determines exact solutions of the equations for a thin disk
with a simultaneous consideration of alpha(omega) and alpha square
effects with a helicity function of alpha of the delta-type. It is shown
that such helicity can originate in a rotating turbulent disk with a
density discontinuity. The solutions have a discontinuous character,
and an associated specific nonlinear effect was also found.
---------------------------------------------------------
Title: The Turbulent Dynamo in a Disk
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Turchaninov, V. L.
1980SvA....24..182R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The turbulent dynamo in a disk
Authors: Ruzmaikin, A. A.; Sokoloff, D. D.; Turchaninoff, V. I.
1980AZh....57..311R Altcode:
The large-scale magnetic field in a rotating, turbulent gaseous
disk will be generated by a dynamo process (the alpha-omega-dynamo)
determined by the differential rotation omega (r) and the spirality
function alpha (z). The generation is best described by a difference
approximation to the dynamo equations, using a step greater than the
turbulence correlation length and a smooth function alpha (z). The
critical dynamo-number for exciting the lowest even quadrupole
mode is Dq = -8. The odd dipole mode will be excited only for large
dynamo-numbers, /Dd/ equal to or greater than 500. When /D/ equal to
or greater than 20, all modes other than the lowest quadrupole mode
(for which the threshold D = -500) are oscillatory. The results are
applied to the Galaxy (D = -10; characteristic growth time, 3 x 10
to the 8th yr) and to accretion disks in binary systems containing a
black hole, where several oscillatory modes can be excited.
---------------------------------------------------------
Title: A disk dynamo with concentrated helicity
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Shukurov, A. M.
1980MagGi.......20R Altcode:
The paper determines exact solutions of the equations for a thin disk
with a simultaneous consideration of alpha(omega) and alpha square
effects with a helicity function of alpha of the delta-type. It is shown
that such helicity can originate in a rotating turbulent disk with a
density discontinuity. The solutions have a discontinuous character,
and an associated specific nonlinear effect was also found.
---------------------------------------------------------
Title: The Role of Differential Rotation in the Solar Dynamo
Authors: Ivanova, T. S.; Ruzmaikin, A. A.
1980SvA....24...75I Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The role of differential rotation in the solar dynamo
Authors: Ivanova, T. S.; Ruzmaikin, A. A.
1980AZh....57..127I Altcode:
A nonlinear magnetohydrodynamic model of the solar dynamo is
considered. It is shown that in order for the solar dynamo theory
to be consistent with observations it is necessary that the angular
velocity of the convective shell have a radial gradient and that this
gradient be negative.
---------------------------------------------------------
Title: Helicity, linkage and dynamo action
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1980GApFD..16...73R Altcode:
A flux helicity pseudoscalar that determines the number of linked flow
lines in a simply connected volume is introduced along with a scalar
that is proportional to the number of linkages of flow lines with
magnetic field lines. These quantities are used to develop a topological
formulation of an antidynamo theorem. The conditions required for slow
dynamo action are clarified, and the relation between flux helicity
and the usual vortex helicity is considered.
---------------------------------------------------------
Title: The turbulent dynamo in astrophysics
Authors: Vainshtein, S. I.; Zeldovich, Ia. B.; Ruzmaikin, A. A.
1980MoIzN....R....V Altcode:
The work examines fundamental aspects of the derivation of equations of
generation and restructuring of magnetic fields in dynamo theory. The
generation and restructuring processes are examined in the linear and
nonlinear field approximations. As examples, consideration is given
to the solar dynamo, the generation of the large-scale magnetic field
of the Galaxy, and magnetic fields and vortex motions in cosmology.
---------------------------------------------------------
Title: The Disc Dynamo
Authors: Ruzmaikin, A. A.; Turchaninov, V. I.; Zeldovich, Ia. B.;
Sokoloff, D. D.
1979Ap&SS..66..369R Altcode:
The simplest αω dynamo in a thin disk is analysed. It the
antisymmetric helicity function α(z) (wherez is a coordinate
perpendicular to the disk plane) is smooth and limited, then the
conditions for generating a magnetic field and the symmetry of the
resulting solutions depend only on the form of α at the segment (0,h)
— whereh is the half-thickness of the disk — and the value of the
dimensionless dynamo numberD. When α(z) does not change its sign at
this segment andD>D <SUB> c </SUB>(the critical dynamo number),
the excitation of non-oscillating even (quadrupole) and oscillating
odd (dipole) fields are possible. When α(z) changes its sign at the
segment indicated, non-oscillating odd magnetic fields can also be
excited. The old exact solutions of the disk αω dynamo are studied
and new ones are found. The results can be of importance when applied
to the problem of the generation of a magnetic field in galactic and
turbulent disks appearing around some X-ray sources.
---------------------------------------------------------
Title: The calculation of Faraday rotation measures of cosmic radio
sources.
Authors: Ruzmaikin, A. A.; Sokoloff, D. D.
1979A&A....78....1R Altcode:
Summary. An observational procedure and a method to calculate rotation
measures and the intrinsic position angles of polarization of cosmic
radio sources is proposed. To avoid the difficulty introduced by the
ambiguity of a position angle (* kx, k =0,1,2,...) it is necessary
firstly to carry out the observations at two sufficiently close
wavelengths and then to choose the next wavelength so that only one
value of the position angle will fall into a cone of possible straight
lines drawn through the previous wavelengths. The calculation procedure
is realized with a computer. The method has been applied to a sample
(of non specialized data) of observations available and the rotation
measures and intrinsic position angles for 145 radio sources have been
obtained, 35 of them are new and the rest coincide partially with those
previously published. The main characteristic of the extragalactic
radio sources in our catalogue is the nearly complete absence of very
large rotation measures (>200 rad/m2). This is evidence against
the hypothesis of an extragalactic radio source population with large
rotation measures (Kronberg and SimardNormardin, 1976). Key words:
rotation measure - position angle - polarisation data processing -
extragalactic and galactic radio sources
---------------------------------------------------------
Title: Faraday rotation in galaxies and absorption lines of quasars.
Authors: Komberg, B. V.; Ruzmaikin, A. A.; Sokolov, D. D.
1979PAZh....5...73K Altcode:
The proposal is made that the dispersion in rotation measure or the
dispersion in depolarization be estimated for various samples of quasars
(with and without absorption lines in their optical spectrum) with
red shifts in the range 1.7-2.4. The difference in these dispersions
for quasars with and without absorption lines would, in principle,
yield the rotation measure for intervening galaxies along the line of
sight that are responsible for the absorption lines.
---------------------------------------------------------
Title: A disk dynamo
Authors: Zeldovich, Ia. B.; Ruzmaikin, A. A.; Sokolov, D. D.;
Turchaninov, V. I.
1979MoIPM.........Z Altcode:
The paper deals with a simple magnetic self-generating dynamo with
an asymmetric helicity function in a thin disk. New exact solutions
for the steady-state dynamo are obtained, and the properties of known
exact solutions are analyzed. The results obtained are of importance
to the generation of magnetic fields in the Galaxy and in turbulent
disks of the type observed about some X-ray sources.
---------------------------------------------------------
Title: Faraday rotation in galaxies, and absorption lines in quasars
Authors: Komberg, B. V.; Ruzmaikin, A. A.; Sokolov, D. D.
1979SvAL....5...40K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Nature of One Mechanism of Solar Differential Rotation
Authors: Ruzmaikin, A. A.; Vainshtein, S. I.
1978Ap&SS..59..215R Altcode:
The mechanism of the solar differential rotation usually ascribed
to an anisotropic viscosity action is shown to be caused by Coriolis
forces which influence anisotropic convective elements in a stratified
medium. The estimation of an anisotropy parameters as a function of
the convective zone depth is given. The value of (s-1) is positive
near the solar surface and negative at the convective zone base,
which is in good agreement with observations and the dynamo theory.
---------------------------------------------------------
Title: Galactic magnetic field parameters determined from Faraday
rotation of radio sources
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Kovalenko, A. V.
1978SvA....22..395R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Galactic magnetic field parameters determined from Faraday
rotation of radio sources
Authors: Ruzmaikin, A. A.; Sokolov, D. D.; Kovalenko, A. V.
1978AZh....55..692R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Magnetic Field Transfer in the Solar Convective Zone
Authors: Ruzmaikin, A. A.; Vainshtein, S. I.
1978Ap&SS..57..195R Altcode:
The large-scale azimuth magnetic field is pumping to the bottom
of the solar convective zone due to the diamagnetic action of
turbulent conductive fluids. When the field at the bottom is of about
10<SUP>3</SUP> G, an equilibrium is established between diamagnetic
pumping and buoyancy. If, in addition to the density gradient, an
additional anisotropy exists (for instance, due to rotation), another
mechanism of the magnetic field transfer appears, the efficiency of
which greatly depends on the magnitude of the anistropy parameter.
---------------------------------------------------------
Title: Erratum: "The scale and strength of the galactic magnetic
field according to the pulsar data" [Astrophys. Space Sci., Vol. 52,
p. 365 - 374, 374 - 385 (1977)].
Authors: Ruzmaikin, A. A.; Sokoloff, D. D.
1978Ap&SS..56..519R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A method for determining the large-scale magnetic field in
the solar corona
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1978PAZh....4...23R Altcode:
A method is developed for determining the magnetic field in the solar
corona from observations of the Faraday rotation of many discrete radio
sources projected against the corona. With this method the averaged
characteristics of the coronal magnetic field and electron density
can be obtained by using Tikhonov's (1963) method to solve a Fredholm
integral equation of the first kind. The observations required to
implement the proposed method are discussed, and a simple estimate of
the expected solution is examined. A list of 42 extragalactic radio
sources and pulsars which 'pass through' the corona at an angular
distance of no more than 5 deg from the center of the sun is given.
---------------------------------------------------------
Title: A method for determining the large-scale magnetic field in
the solar corona
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1978SvAL....4...12R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The galaxy magnetic field
Authors: Ruzmaikin, A. A.
1978cdeo.coll...73R Altcode: 1978IAUCo..45...73R; 1977cdeo.coll...73R
The paper considers the dynamo theory for the generation of the Galactic
magnetic field. The Galactic dynamo model contains two mechanisms
which act simultaneously: (1) the stretching of the azimuth field
away from the meridional field due to differential rotation, and (2)
the generation of a meridional component from the azimuth field by
means of helical turbulence. Magnetic field generation is discussed
with reference to certain problems of Galactic dynamics and evolution.
---------------------------------------------------------
Title: The Scale and Strength of the Galactic Magnetic Field According
to the Pulsar Data (In Russian)
Authors: Ruzmaikin, A. A.; Sokoloff, D. D.
1977Ap&SS..52..375R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Scale and Strength of the Galactic Magnetic Field According
to the Pulsar Data
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1977Ap&SS..52..365R Altcode:
In accordance with the data on the Faraday rotation, angular
coordinates, and dispersion measurements and distances of 38 pulsars,
the strengthB=2.1±1.1 μG and directionl=99°±24°,b≅0° of the
large-scale galactic magnetic field and the mean electron density
in the galactic discN <SUB>e</SUB>=0.03±0.01 cm<SUP>-3</SUP> are
determined. A comparison with the results of a study of the measures
of rotation of extragalactic radio sources enabled us to estimate the
characteristic half-width of the distribution of the electron density
on the Z-coordinate (h≅400 ps). The characteristic size of galactic
magnetic field flucturations is shown to be ℒ=100 150 ps.
---------------------------------------------------------
Title: A nonlinear magnetohydrodynamic model of the solar dynamo
Authors: Ivanova, T. S.; Ruzmaikin, A. A.
1977AZh....54..846I Altcode:
A numerical solution is developed for the simplest nonlinear MHD dynamo
model of large-scale magnetic-field generation in the solar convection
zone. The nonlinearity is introduced by varying the form of the function
that describes the helicity of the velocity field. As a result, growing
oscillations are suppressed, and a steady-state solution is obtained
for a given period and amplitude. Phase relations between the meridional
and azimuthal magnetic-field components are examined, a limit is placed
on the dependence of angular velocity on convection-zone depth, and a
butterfly diagram in qualitative agreement with the observed diagram
is plotted. Estimates of the steady-state dynamo number, period,
and amplitude are also found to be in good agreement with observations.
---------------------------------------------------------
Title: A nonlinear magnetohydrodynamic model of the solar dynamo
Authors: Ivanova, T. S.; Ruzmaikin, A. A.
1977SvA....21..479I Altcode:
A numerical solution is developed for the simplest nonlinear MHD dynamo
model of large-scale magnetic-field generation in the solar convection
zone. The nonlinearity is introduced by varying the form of the function
that describes the helicity of the velocity field. As a result, growing
oscillations are suppressed, and a steady-state solution is obtained
for a given period and amplitude. Phase relations between the meridional
and azimuthal magnetic-field components are examined, a limit is placed
on the dependence of angular velocity on convection-zone depth, and a
butterfly diagram in qualitative agreement with the observed diagram
is plotted. Estimates of the steady-state dynamo number, period,
and amplitude are also found to be in good agreement with observations.
---------------------------------------------------------
Title: The interpretation of rotation measures of extragalactic
radio sources.
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1977A&A....58..247R Altcode:
The Galactic, intrinsic source, and intergalactic-magnetic-field
contributions to the observed rotation measures (RM) of extragalactic
radio sources are studied simultaneously in the framework of a
simple model in which the observed RM is represented as the sum of
these three contributions. A regression method is used to obtain
the model parameters as well as information on the magnitude of
possible selection and evolutionary effects. The analysis is applied
to selected extragalactic radio sources listed in three basic catalogs;
it is found that the value of the Galactic contribution is practically
independent of redshift and the mass density of the universe, while
the intergalactic-magnetic-field contribution is insignificant. The
magnitude of the large-scale Galactic magnetic field is estimated
to be about 4.5 microgauss, and it is concluded that there is no
definite evidence for the existence of a homogeneous intergalactic
magnetic field.
---------------------------------------------------------
Title: Anisotropic cosmological solutions in the gravitational theory
with quadratic invariants.
Authors: Ruzmaikin, A. A.
1977Afz....13..345R Altcode:
It is noted that quantum modifications of the general-relativistic
equations near the cosmological singularity can be partially achieved
by adding terms in the square of the curvature tensor to the Lagrangian
of the gravitational field. Such a modified theory is found to yield
solutions with a regular minimum at t = 0 in the general anisotropic
case. However, analysis of the simplest homogeneous and anisotropic
metric indicates that these solutions are not characterized by
power-law asymptotic behavior as t tends to infinity. It is shown
that allowance for certain logarithmic terms in the curvature tensor
alters the situation slightly, at least in the isotropic case. It is
concluded that effects of particle production and possibly of nonlocal
terms must be taken into account in a self-consistent manner in order
to resolve the question of whether the cosmological singularity can
be eliminated by a transformation to power-law behavior.
---------------------------------------------------------
Title: Anisotropic cosmological solutions in the theory of gravitation
with quadratic invariants
Authors: Ruzmaikin, A. A.
1977Ap.....13..186R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Nonhomogeneous large-scale magnetic field and the global
structure of the universe.
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1977Afz....13...95R Altcode:
Previous analysis of observational data on the Faraday rotation of
radio emission from extragalactic sources has indicated the existence
of a large-scale universal magnetic field. This paper proposes that
that large-scale field is associated with the topological structure
of the universe. It is assumed that the observed anisotropies in
topological gluing and field direction have a common origin and that
the characteristic scale of the magnetic field determines the scale
of gluing. It is shown that a specific pattern of source 'ghosts'
arises in such a model and can be observed in principle.
---------------------------------------------------------
Title: Inhomogeneous large-scale magnetic field and global structure
of the Universe
Authors: Ruzmaikin, A. A.; Sokolov, D. D.
1977Ap.....13...50R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Accretion of Matter by a Collapsing Star in the Presence
of a Magnetic Field. II: Self-consistent Stationary Picture
Authors: Bisnovatyi-Kogan, G. S.; Ruzmaikin, A. A.
1976Ap&SS..42..401B Altcode:
The stationary two-dimensional magnetohydrodynamic solution for the
accretion of the matter without pressure into a gravitating centre
of a black hole is obtained. It is assumed that the magnetic field
far from the collapsed star is homogeneous and its influence on the
flow is negligible. Around the star, at the plane perpendicular to
the direction of the magnetic field, the dense quasistationary disc
is formed, the structure of which in a large extent is determined by
dissipation processes. The structure is calculated for (a) a laminar
disc with the Coulomb mechanism of dissipation; and (b) a turbulent
disc. The estimations of the parameters of the shock which result from
the infall of the matter onto the disc are given. In the last section
the numerical estimation and approximate character of the radiation
spectrum of the disc and the shock are obtained for two cases of 10M
<SUB>⊙</SUB> and 10<SUP>5</SUP> M <SUB>⊙</SUB>. The luminosity of
collapsed objects withM=10M <SUB>⊙</SUB> appears to be about solar,
thus its observation is possibly only at the distances less than 300
1000 pc. The collapsed objects in the Galaxy withM=10<SUP>5</SUP> M
<SUB>⊙</SUB> could constitute very bright sources in spectral regions
from optical up to X-ray. The spectra of a laminar and a turbulent disc
for 10M <SUB>⊙</SUB> black hole are very different. The laminar disc
radiates primarily in the ultraviolet. The turbulent disc radiates a
large part of its flux in the infrared. Therefore, one cannot exclude
the possibility that some of the galactic infrared star-like sources
are individual black holes in the accretion state.
---------------------------------------------------------
Title: The Accretion of Matter by a Collapsing Star in the Presence of
a Magnetic Field. II: Self-consistent Stationary Picture (In Russian)
Authors: Bisnovatyi-Kogan, G. S.; Ruzmaikin, A. A.
1976Ap&SS..42..375B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Possible evaluation of the magnetic field near pulsars from
the beat frequency of atomic transitions
Authors: Ruzmaikin, A. A.
1976SvA....19..702R Altcode:
For the determination of the magnetic field in astrophysical
conditions the use of the 'beats' effect in the atomic transitions is
suggested. The frequency of beats under the Zeeman split is proportional
to the magnetic field; its Doppler spread is negligible. The synphase
excitation of atoms can be accomplished by means of the short pulse of
the linear polarized light. The concrete estimations are made for the
case of the forbidden lines in the Crab nebula excited by the optic
pulse of the pulsar NP 0531.
---------------------------------------------------------
Title: Astrophysical magnetic fields determined from polarization
by atomic fluorescence
Authors: Ruzmaikin, A. A.
1976AZh....53..550R Altcode:
It is noted that the polarization of resonance radiation is very
sensitive to the effect of external magnetic fields and that
interference between the Zeeman components of such radiation for
quasi-degenerate levels yields a linearly polarized line with a
rotating plane of polarization, provided the exciting light has
a broad spectrum. Polarization of resonance radiation in a weak
magnetic field is analyzed, and it is shown that the rotation angle
and the degree of polarization are determined by the magnetic-field
intensity. Possibilities of applying this effect as a method
for determining the magnetic fields of astrophysical objects are
considered. The magnitude of the effect is estimated for several
forbidden lines of the solar corona and Seyfert galaxy nuclei as well
as for some cometary molecular and atomic lines.
---------------------------------------------------------
Title: Astrophysical magnetic fields determined from polarization
by atomic fluorescence
Authors: Ruzmaikin, A. A.
1976SvA....20..311R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Magnetohydrodynamic dynamo model of the solar cycle
Authors: Ivanova, T. S.; Ruzmaikin, A. A.
1976SvA....20..227I Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Magnetohydrodynamic dynamo model of the solar cycle
Authors: Ivanova, T. S.; Ruzmaikin, A. A.
1976AZh....53..398I Altcode:
The hydromagnetic-dynamo model of the cyclic process in the sun's
convective zone, in which differential rotation and gyrotropic
turbulent convective motions play the main role, is investigated. The
employed difference method for the numerical solution of the basic
equations of magnetic-field generation allows the system of unsteady
partial differential equations to be solved without reducing it to
the eigenvalue problem. The principal results are the following:
(1) an oscillatory solution in the quadrupole mode is obtained;
(2) it is shown that the period of the oscillations and the critical
dynamo number essentialy depend on the jump in the conductivity at
the boundary between the convective zone and the radiative nucleus as
well as on the diamagnetism of the convective zone. In particular, the
diamagnetic effect can strongly increase the period of the oscillations.
---------------------------------------------------------
Title: Possible evaluation of the magnetic field near pulsars from
the beat frequency of atomic transitions
Authors: Ruzmaikin, A. A.
1975AZh....52.1173R Altcode:
For the determination of the magnetic field in astrophysical
conditions the use of the 'beats' effect in the atomic transitions is
suggested. The frequency of beats under the Zeeman split is proportional
to the magnetic field; its Doppler spread is negligible. The synphase
excitation of atoms can be accomplished by means of the short pulse of
the linear polarized light. The concrete estimations are made for the
case of the forbidden lines in the Crab nebula excited by the optic
pulse of the pulsar NP 0531.
---------------------------------------------------------
Title: Collisionless generation of rotation in galaxies
Authors: Ruzmaikin, A. A.
1975PAZh....1...10R Altcode:
No abstract at ADS
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Title: Collisionless generation of rotation in galaxies
Authors: Ruzmaikin, A. A.
1975SvAL....1...95R Altcode:
No abstract at ADS
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Title: Determination of astrophysical magnetic fields from the
polarization of atomic fluorescence
Authors: Ruzmaikin, A. A.
1975MoIPM.........R Altcode:
It is well known that polarization of atomic fluorescence is sensitive
to the action of weak magnetic fields. In the case of excitation by
light with a wide spectrum, the interference of the Zeeman components
for a quasi-degenerate level gives a linearly polarized line with a
rotating polarization plane. The angle of rotation and the degree of
polarization are defined by the magnitude of the magnetic field. The
aim of the present book is to give a physically acceptable description
of this effect, and to examine various means of using it to determine
astrophysical magnetic fields.
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Title: The Accretion of Matter by a Collapsing Star in the Presence
of a Magnetic Field
Authors: Bisnovatyi-Kogan, G. S.; Ruzmaikin, A. A.
1974Ap&SS..28...45B Altcode:
The exact nonstationary solution for the variation of the magnetic
field in the Schwarzschild metric with a given spherically symmetric
flow is obtained. Initially a homogeneous magnetic field increases
with time, changing into a quasi-radial field. On the assumption of
equipartition between the magnetic and kinetic energies of a falling
gas, in the relativistic case, estimates of the stationary field and
the intensity of synchrotron radiation are presented. A considerable
part of the radiation is formed in the relativistic regionr≲(2.5 to
7.7)r <SUB> g </SUB>(r <SUB> g </SUB> is the gravitational radius of
a black hole). Estimates are made for radiation from the relativistic
region in the case of disc type accretion.
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Title: The Accretion of Matter by a Collapsing Star in the Presence
of a Magnetic Field (In Russian)
Authors: Bisnovatyi-Kogan, G. S.; Ruzmaikin, A. A.
1974Ap&SS..28...31B Altcode:
No abstract at ADS
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Title: The Stability of Rotating Supermassive Stars
Authors: Bisnovaty-Kogan, G. S.; Ruzmaikin, A. A.
1973A&A....27..209B Altcode:
Summary. Supermassive stars (those with M> 10 M0) are maintained
in equilibrium by their radiation pressure. However, when first order
general relativistic effects are taken into account, such stars are
seen to be unstable against collapse, and rotation can become the
most important means of establishing their stability: in this paper
this is investigated by adding to the usual expressions for the full
mass-energy, rest mass and angular momentum deviations arising from
the second order post-newtonian corrections of general relativity in
stationary, rotating configurations. These corrections are obtained by
expanding the exact Einstein expressions to order 1/c4. The approximate
"energy" method is then used to study stability against collapse;
the energy functional is written in terms of two parameters - Qc,
the central density, and cc, a measure of oblateness - and its first
and second variations define the state of the star. When the first
variation vanishes, the star is in equilibrium, and if the second
is positive it is also stable. We have found that: J2> J? =0.19 (
2GcMO2 )2 leads to stable equilibrium: when J? <J2 <J22 =0.35
(2GcMO2 )2 the star in the course of time becomes unstable against
collapse: when j2 > J22 the star eventually forms itself into a
thin disc. Our results are applied to a model of a quasar Key words:
general relativity - post-newtonian corrections - stability
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Title: Star Contraction and Magnetic-Field Generation in
Protogalaxies.
Authors: Bisnovatyi-Kogan, G. S.; Ruzmaikin, A. A.; Syunyaev, R. A.
1973SvA....17..137B Altcode:
No abstract at ADS
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Title: Relativistic Vortex Motion
Authors: Vainshtein, S. I.; Ruzmaikin, A. A.
1973SvA....17....7V Altcode:
No abstract at ADS
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Title: Relativistic Vortex Motion
Authors: Vainshtein, S. I.; Ruzmaikin, A. A.
1973AZh....50...12V Altcode:
No abstract at ADS
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Title: Star Contraction and Magnetic-Field Generation in
Protogalaxies.
Authors: Bisnovatyi-Kogan, G. S.; Ruzmaikin, A. A.; Syunyaev, R. A.
1973AZh....50..210B Altcode:
No abstract at ADS
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Title: Generation of the Large-Scale Galactic Magnetic Field. II.
Authors: Vainshtein, S. I.; Ruzmaikin, A. A.
1972SvA....16..365V Altcode:
No abstract at ADS
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Title: Generation of the Large-Scale Galactic Magnetic Field.
Authors: Vainshtein, S. I.; Ruzmaikin, A. A.
1972SvA....15..714V Altcode:
No abstract at ADS
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Title: Generation of the Large-Scale Galactic Magnetic Field. II.
Authors: Vainshtein, S. I.; Ruzmaikin, A. A.
1972AZh....49..449V Altcode:
No abstract at ADS
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Title: On the Generation of Magnetic Field in Rotating Relativistic
Objects
Authors: Bisnovaty-Kogan, G. S.; Ruzmaikin, A. A.
1972A&A....17..243B Altcode:
It is shown that there is no magnetic field generation in a stationary
rotating relativistic star if Q = const in the case of a barotropic
medium and in an isentropic star with Q const. Key words: rotation -
relativity - magnetic field generation
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Title: Generation of the Large-Scale Galactic Magnetic Field.
Authors: Vainshtein, S. I.; Ruzmaikin, A. A.
1971AZh....48..902V Altcode:
No abstract at ADS
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Title: Gravitational Stability of an Expanding Universe in the
Presence of a Magneric Field.
Authors: Ruzmaikina, T. V.; Ruzmaikin, A. A.
1971SvA....14..963R Altcode:
No abstract at ADS
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Title: Gravitational Stability of an Expanding Universe in the
Presence of a Magneric Field.
Authors: Ruzmaikina, T. V.; Ruzmaikin, A. A.
1970AZh....47.1206R Altcode:
No abstract at ADS
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Title: The story told by the anisotropy of the relict radiation.
Authors: Ruzmaikin, A. A.
1970Prir....5...68R Altcode:
No abstract at ADS
