Author name code: benevolenskaya
ADS astronomy entries on 2022-09-14
author:"Benevolenskaya, Elena E."
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Title: Pulsed nature of solar cycle 24
Authors: Benevolenskaya, E. E.; Ponyavin, Yu. D.
Bibcode: 2015Ge&Ae..55..907B
Altcode:
Solar cycle 24 is characterized by relatively weak sunspot activity and
is developing according to the smallest cycle scenario (Svalgaard,
Cliver, and Kamide, 2005). Using the Solar Dynamics Observatory
(SDO) data for May 2010-September 2014, we present the results of
a study of solar cycle 24 in the photosphere and corona during the
ascending and maximum epochs. These data have been prepared in the
form of synoptic maps (one map corresponds to one solar rotation)
as functions of latitude and longitude for Carrington rotations
CR2097-CR2154. To study the axisymmetric structure of the cycle,
the maps have been averaged over longitude. Solar activity pulses,
which are visible in an axisymmetric midlatitude magnetic flux,
correspond to coronal brightening events in the extreme ultraviolet
in the 193 Å band. Solar cycle 24 is characterized by weak magnetic
polar activity, weakly pronounced high-latitude waves of coronal
activity, and north-south asymmetry in the sign change of the polar
solar magnetic field, which is directly connected with the asymmetry
in an emerging magnetic flux in the region of sunspot activity and,
hence, solar activity pulses. Thus, the north polar field became
mainly positive in the latitude zone from 75.01° to 79.73° in 2013,
while the south field started changing sign in September 2014.
Title: The features of longitudinal distribution of solar spots
during the last 13 solar activity minima
Authors: Kostuchenko, I. G.; Benevolenskaya, E. E.
Bibcode: 2015Ge&Ae..55.1039K
Altcode:
We analyzed the features of the longitudinal distribution of the
areas of solar spots during the solar activity minima, from the 11th
cycle to the last minimum, based on data provided by the Greenwich
Observatory and the Marshall Research Center. We discovered that
the solar spots evolved in one or two neighboring bands (in terms of
longitude), the Carrington longitude of which smoothly displaced from
the east to the west, in the phase of the deep minimum in all of the
considered cases. The spots at the high latitudes associated with a
"new" cycle evolved on the same longitude bands. All of this led to the
noticeable longitudinal asymmetry of magnetic fluxes related to the
spots and flocculi. Based on our research, we propose the hypothesis
that a nonaxisymmetric component of the total magnetic flux of the Sun
is generated, together with the dipole component, by the solar dynamo
mechanism, which is a typical feature of the phase of a minimum between
the solar activity cycles.
Title: Solar spectral irradiance and total solar irradiance at a
solar minimum
Authors: Benevolenskaya, E. E.; Shapovalov, S. N.; Kostuchenko, I. G.
Bibcode: 2014Ge&Ae..54..926B
Altcode:
Results are presented for a wavelet analysis of solar spectral
irradiance (SSI) in the ultraviolet to infrared range and total solar
irradiance (TSI). The study is based on data collected by the Solar
Radiation and Climate Experiment ( SORCE) satellite from March 10,
2007 to January 23, 2010. Cross-wavelet analysis finds relationships
of varying degrees of tightness between SSI, TSI, and magnetic flux
in a sunspot zone on the surface rotation timescales of solar activity
complexes. Wavelet coherence shows how magnetic flux variations within
a latitudinal sunspot zone are related with spectral irradiance
variations. For example, variations in ultraviolet radiation at UV
200.5 nm are in phase with those of the magnetic flux associated with
solar activity complexes. However, there is an unusual interval UV
310 to 380 nm, in which coherent structures disappear and UV radiation
variations do not follow the changes in the magnetic flux.
Title: Active longitudes in minima of solar activity
Authors: Kostuchenko, I. G.; Benevolenskaya, E. E.
Bibcode: 2014Ge&Ae..54.1019K
Altcode:
The evolution of the solar magnetic flux and ultraviolet radiation in
the two minima of solar activity are analyzed and compared with the
results of the last minimum analysis. It was found that in all three
minima the spots and flocculi (faculae) of both the old and new cycles
associated with them appear in the selected longitude intervals. It
indicates the existence of a nonaxisymmetric component of the magnetic
field generated by the dynamo mechanism. It is shown that despite low
values of magnetic fluxes in the sunspot activity region in the epoch
of minima, they have a significant influence on processes in the solar
chromosphere and corona, and, as a result, affect the variation of
solar ultraviolet radiation.
Title: Synoptic Solar Cycle 24 in Corona, Chromosphere, and
Photosphere Seen by the Solar Dynamics Observatory
Authors: Benevolenskaya, E.; Slater, G.; Lemen, J.
Bibcode: 2014SoPh..289.3371B
Altcode: 2014SoPh..tmp...71B
The Solar Dynamics Observatory provides multiwavelength imagery from
extreme ultraviolet (EUV) to visible light as well as magnetic-field
measurements. These data enable us to study the nature of solar activity
in different regions of the Sun, from the interior to the corona. For
solar-cycle studies, synoptic maps provide a useful way to represent
global activity and evolution by extracting a central meridian band from
sequences of full-disk images over a full solar Carrington rotation (≈
27.3 days). We present the global evolution during Solar Cycle 24 from
20 May 2010 to 31 August 2013 (CR 2097 - CR 2140), using synoptic maps
constructed from full-disk, line-of-sight magnetic-field imagery and
EUV imagery (171 Å, 193 Å, 211 Å, 304 Å, and 335 Å). The synoptic
maps have a resolution of 0.1 degree in longitude and steps of 0.001
in sine of latitude. We studied the axisymmetric and non-axisymmetric
structures of solar activity using these synoptic maps. To visualize the
axisymmetric development of Cycle 24, we generated time-latitude (also
called butterfly) images of the solar cycle in all of the wavelengths,
by averaging each synoptic map over all longitudes, thus compressing
it to a single vertical strip, and then assembling these strips in
time order. From these time-latitude images we observe that during the
ascending phase of Cycle 24 there is a very good relationship between
the integrated magnetic flux and the EUV intensity inside the zone
of sunspot activities. We observe a North-South asymmetry of the EUV
intensity in high-latitudes. The North-South asymmetry of the emerging
magnetic flux developed and resulted in a consequential asymmetry in
the timing of the polar magnetic-field reversals.
Title: Solar cycle 24 in Photosphere, Chromosphere and Corona.
Authors: Benevolenskaya, Elena
Bibcode: 2014cosp...40E.280B
Altcode:
The solar cycle 24 shows an interesting behavior and it is a subject of
current discussions. Comparison this cycle with previous ones displays
relatively small activity which may be a consequence of the interaction
of the long-tem variations of the solar activity and sunspot solar
cycle. For example, the Solar Dynamics Observatory (SDO) provides us
with multi-waves imagery from Extreme Ultraviolet (EUV) to visible
light as well as magnetic field measurements. These data give us an
opportunity to study the nature of solar activity in different regions
of the Sun, from the interior to the corona. For solar cycle studies
synoptic maps provide a useful way to represent global activity and
evolution by extracting a central meridian band from sequences of full
disk images over a full solar Carrington rotation (~ 27.3 days). Here,
present the global evolution of solar cycle 24 from May 20, 2010 to
up the present, using synoptic maps constructed from full disk line-of
sight magnetic field imagery (HMI/SDO) and EUV imagery (171Å, 193Å,
211Å, 304Å and 335Å (AIA/SDO). The synoptic maps have a resolution of
0.1 degree in longitude and steps of 0.001 in sine of latitude. From the
'time-latitude' images we observe that during the ascending phase of
cycle 24 a very strong North-South asymmetry of topology of emerging
magnetic flux develops, resulting in a consequential asymmetry in the
timing of the polar magnetic field reversals.
Title: Multi-wavelength solar activity complexes evolution from
Solar Dynamic Observatory (SDO)
Authors: Korolkova, Olga; Benevolenskaya, Elena
Bibcode: 2014cosp...40E1586K
Altcode:
The main problem of the solar physics is to understand a nature of the
solar magnetic activity. New space missions and background observations
provide us by data describing solar activity with a good space and
time resolution. Space missions data observe the solar activity in
multi-wavelength emissions come from photosphere to corona. The complex
of the solar activity has roots in inte-rior and extends to the solar
corona. Thus, modern data give an opportunity to study the activity on
the Sun at different levels simultaneously. Solar Dynamics Observatory
(SDO) [1] which launched at the beginning of 2010, looks at Sun in
different wavelengths such as coronal lines 171Å & 335Å. Also
SDO measures photospheric magnetic flux (line-of-sight component of the
magnetic field strength) and gives images in continuum. We have studied
a stable complexes of the solar activity (about 30 com-plexes) during 6
hours from 10 March 2013 to 14 October 2013 using 720s ca-dence of HMI
(Helioseismic and Magnetic Imager) [2] and AIA (Atmospheric Imaging
Assembly) [3] instruments of SDO. We have found a good relationship
between the magnetic flux and coronal emissions. Here we discuss
properties of the complexes in the different levels from photosphere to
corona. References 1. W. Dean Pesnell, B.J. Thompson, P.C. Chamberlin
// Solar Phys., v. 275, p. 3-15, (2012). 2. P.H. Scherrer, J. Schou,
R.I. Bush et al. // Solar Phys., v. 275, p. 207-227, (2012). 3. James
R. Lemen • Alan M. Title • David J. Akin et al. // Solar Phys.,
v. 275, p. 17-40, (2012).
Title: Solar polar magnetic field
Authors: Benevolenskaya, E. E.
Bibcode: 2013Ge&Ae..53..891B
Altcode:
The solar polar magnetic field has attracted the attention of
researchers since the polar magnetic field reversal was revealed in
the middle of the last century (Babcock and Livingston, 1958). The
polar magnetic field has regularly reversed because the magnetic flux
is transported from the sunspot formation zone owing to differential
rotation, meridional circulation, and turbulent diffusion. However,
modeling of these processes leads to ambiguous conclusions, as a
result of which it is sometimes unclear whether a transport model
is actual. Thus, according to the last Hinode data, the problem of
a standard transport model (Shiota et al., 2012) consists in that a
decrease in the polar magnetic flux in the Southern Hemisphere lags
behind such a decrease in the flux in the Northern Hemisphere (from
2008 to June 2012). On the other hand, Svalgaard and Kamide (2012)
consider that the asymmetry in the sign reversal simply results from
the asymmetry in the emerging flux in the sunspot formation region. A
detailed study of the polar magnetic flux evolution according to the
Solar Dynamics Observatory (SDO) data for May 2010-December 2012 is
illustrated in the present work. Helioseismic & Magnetic Imager
(HMI) magnetic data in the form of a magnetic field component along
the line of sight (the time resolution is 720 s) are used here. The
magnetic fluxes in sunspot formation regions and at high latitudes
have been compared.
Title: The total solar irradiance, UV emission and magnetic flux
during the last solar cycle minimum
Authors: Benevolenskaya, E. E.; Kostuchenko, I. G.
Bibcode: 2013arXiv1307.6257B
Altcode:
We have analyzed the total solar irradiance (TSI) and the spectral
solar irradiance as ultraviolet emission (UV) in the wavelength range
115-180 nm, observed with the instruments TIM and SOLSTICE within the
framework of SORCE (The Solar Radiation and Climate Experiment) during
the long solar minimum between the 23rd and 24th cycles. The wavelet
analysis reveals an increase in the magnetic flux in the latitudinal
zone of the sunspot activity, accompanied with an increase in the
TSI and UV on the surface rotation timescales of solar activity
complexes. In-phase coherent structures between the mid-latitude
magnetic flux and TSI/UV appear when the long-lived complexes of the
solar activity are present. These complexes, which are related to
long- lived sources of magnetic fields under the photosphere, are
maintained by magnetic fluxes reappearing in the same longitudinal
regions. During the deep solar minimum (the period of the absence of
sunspots) a coherent structure has been found, in which the phase
between the integrated mid-latitude magnetic flux is ahead of the
total solar irradiance on the timescales of the surface rotation.
Title: Magnetic flux evolution inside and outside a polar coronal
hole based on data from the Solar Dynamics Observatory (SDO)
Authors: Benevolenskaya, E. E.
Bibcode: 2012Ge&Ae..52..829B
Altcode:
This paper presents the analysis results of the magnetic flux inside
and outside a polar coronal hole in the north during the period August
1-2, 2010. The location of the polar coronal hole is determined from
Extreme Ultraviolet (EUV) images in the Fe XII, XXIV (193 Å) line,
obtained by an Atmospheric Imager Assembly (AIA) of the Solar Dynamics
Observatory (SDO). Magnetic data are represented by the line-of-sight
component of the magnetic field strength, measured with an Helioseismic
and Magnetic Imager (HMI). Both data sets are sampled at an interval
of 720 s and are remapped onto a Carrington coordinate grid with a
resolution of 0.001 in sine latitude and 0.1 degree in longitude. The
preliminary results show a magnetic flux of the new cycle's polarity
(positive polarity in the north) appearing inside the coronal hole on a
time scale of several hours. This "new flux" does not correlate with the
magnetic flux of the old solar cycle (negative polarity in the north).
Title: Synoptic magnetic field in cycle 23 and in the beginning of
the cycle 24
Authors: Benevolenskaya, E. E.; Ponyavin, Yu. D.
Bibcode: 2012AdSpR..50..656B
Altcode:
The SOHO/MDI data provide the uniform time series of the synoptic
magnetic maps which cover the period of the cycle 23 and the
beginning of the cycle 24. It is very interesting period because of
the long and deep solar minimum between the cycles 23 and 24. Synoptic
structure of the solar magnetic field shows variability during solar
cycles. It is known that the magnetic activity contributes to the
solar irradiance. The axisymmetrical distribution of the magnetic flux
(Fig. 3c) is closely associated with the 'butterfly' diagram in the EUV
emission (Benevolenskaya et al., 2001). And, also, the magnetic field
(B∥) shows the non-uniform distributions of the solar
activity with longitude, so-called 'active zones', and 'coronal holes'
in the mid-latitude. Polar coronal holes are forming after the solar
maxima and they persist during the solar minima. SOHO/EIT data in the
emission of Fe XII (195 Å) could be a proxy for the coronal holes
tracking. The active longitudinal zones or active longitude exist
due to the reappearance of the activity and it is clearly seen in the
synoptic structure of the solar cycle. On the descending branch of the
solar cycle 23 active zones are less pronounced comparing with previous
cycles 20, 21 and 22. Moreover, the weak polar magnetic field precedes
the long and deep solar minimum. In this paper we have discussed the
development of solar cycles 23 and 24 in details.
Title: SDO in Pulkovo Observatory
Authors: Benevolenskaya, E.; Efremov, S.; Ivanov, V.; Makarenko, N.;
Miletsky, E.; Okunev, O.; Nagovitsyn, Yu.; Parfinenko, L.; Solov'ev,
A.; Stepanov, A.; Tlatov, A.
Bibcode: 2012ASSP...30..155B
Altcode: 2012snc..book..155B
We discuss effective applications of data obtained by both instruments
of the Solar Dynamics Observatory: The Helioseismic & Magnetic
Imager (HMI) and The Atmospheric Imaging Assembly (AIA). The purpose
of this presentation is to show the most important problems of solar
activity which are the main subjects in Pulkovo Observatory of the
Russian Academy of Science. For these investigations uniform data sets
of magnetic fields and coronal emissions in extreme ultra-violet bands
are needed. Thus, we are planning to create SDO center in Pulkovo
Observatory, which will help us in collaboration with existing SDO
centers and provide more effective way of access to data for studies
of the Sun.
Title: SDO in Pulkovo Observatory
Authors: Benevolenskaya, E. E.; Efremov, V.; Ivanov, V.; Makarenko,
N.; Miletsky, E.; Okunev, O.; Nagovitsin, Y.; Parfinenko, L.; Soloviev,
A.; Stepanov, A.; Tlatov, A.
Bibcode: 2010AGUFMSH23C1877B
Altcode:
We discuss the effective applications of the data obtained with Solar
Dynamics Observatory from both instruments: The Helioseismic Magnetic
Imager (HMI) and The Atmospheric Imaging Assembly (AIA). The purpose
of this presentation is to show the most important problems of solar
activity which are the main subjects in the Pulkovo Observatory. There
with uniform data sets of magnetic fields and coronal emission
in Extreme Ultraviolet bands are needed. Thus, we are planning to
create SDO center in the Pulkovo Observatory, which will helps us in
collaboration with existed SDO centers and provides more convenient
data downloading for solar physics.
Title: Did Recent Large-Scale Evolution of the Magnetic Field Presage
the Unusual Current Minimum?
Authors: Benevolenskaya, E. E.
Bibcode: 2010ASPC..428...93B
Altcode:
The recent investigations of the solar magnetic activity reveal the
unusual behavior during the minimum phase of the solar cycles 23-24. We
observe the unpredictable long solar minimum, and how it is really
unusual. The new magnetic flux is coming but the Sun looks mostly blank
(free of sunspots). During last three cycles the polar magnetic fields
are decreasing. It could be leading to the situation where the poloidal
magnetic field is not sufficient (according to the dynamo theory) to
generate the strong new toroidal magnetic field. From the other hand,
modern dynamo models failed to predict a beginning of the next solar
cycle 24. In this paper I overview the dynamics of the solar magnetic
field inferred from the SOHO/MDI data during the cycle 23 and the
epoch of the overlapping cycles 23 and 24, trying to understand the
puzzle of the modern solar minimum.
Title: Dynamics of the solar magnetic field from SOHO/MDI
Authors: Benevolenskaya, E. E.
Bibcode: 2010AN....331...63B
Altcode:
The investigation of the dynamics of magnetic fields from small scales
to the large scales is very important for the understanding of the
nature of solar activity. It is also the base for producing adequate
models of the solar cycle with the purpose to predict the level of
solar activity. Since December 1995 the Michelson Doppler Imager (MDI)
on board of the Solar and Heliospheric Observatory (SOHO) provides
full disk magnetograms and synoptic maps which cover the period of
solar cycle 23 and the current minimum. In this paper, I review the
following important topics with a focus on the dynamics of the solar
magnetic field. The synoptic structure of the solar cycle; the birth
of the solar cycle (overlapping cycles 23 and 24); the relationship
of the photospheric magnetic activity and the EUV solar corona, polar
magnetic fields and dynamo theory.
Title: Polar coronal holes in cycle 23 inferred from SOHO/EIT data
Authors: Benevolenskaya, Elena; Ponyavin, Yurij
Bibcode: 2010cosp...38.2893B
Altcode: 2010cosp.meet.2893B
The EUV solar corona manifests a rich picture of the coronal topology
from the close configu-ration of the magnetic field up to the open
magnetic flux which is associated with solar coronal holes. Coronal
holes are the source of the high speed solar wind. Results of
the investiga-tion of the EUV solar corona are an important for
the understanding of the stellar EUV and X-ray corona. Extreme
Ultraviolet emission (EUV) inferred from SOHO/EIT data displays the
evolution of the solar coronal holes (plasma regions of low density)
in cycle 23. Usually, it is images in lines Fe XII (195A) and Fe XV
(284A). Polar coronal holes are related to the polar magnetic field
reversal. They forms from the extended mid latitude coronal holes
which are coincided with solar magnetic `surges'. Here, we present the
results of the forming of the polar coronal holes. We discuss their
relationship to the magnetic activity and solar cycle. The filtering
is applied to the EIT images. It is investigated the role of filtering
in the estimation of the topology of the coronal holes.
Title: Topology of the magnetic field in cycle 23 and in the beginning
of the cycle 24
Authors: Benevolenskaya, Elena; Ponyavin, Yurij
Bibcode: 2010cosp...38.1698B
Altcode: 2010cosp.meet.1698B
The solar variability in irradiance is directly related to the solar
magnetic field. The SOHO/ MDI data provide the uniform time series of
the synoptic magnetic maps which covered the period of the cycle 23 and
the beginning of the cycle 24. The axisymmetrical and non-axisymmetrical
distributions of the magnetic field are associated with the EUV coronal
emission. The reappearance of the activity has a tendency to reappear
in clusters of the solar activity or active longitudinal zone. The
weak polar magnetic field precedes the long and deep solar minimum. In
this presentation we have discussed the development of the solar cycle
23. And, how the magnetic activity affects the current solar cycle
Title: High-latitude activity and its relationship to the mid-latitude
solar activity
Authors: Benevolenskaya, E.
Bibcode: 2008AGUFMSH51A1590B
Altcode:
The high-latitude activity at photosphere and corona, and their relation
to the mid-latitude activity in cycle 23 have been explored using the
MDI magnetic synoptic maps available on the SOHO web page with a new
calibration and EIT synoptic maps. The EIT synoptic maps of EUV images
in three lines Fe and in one line He II (171A, 195A, 284A and 304A) are
obtained for period June 1996 - May 2006 (CR1911-CR2042) from the full
disk EIT images. They are represented by values of the line intensity
centered on the central meridian and can be directly compared with
magnetic synoptic maps (MDI maps). It is found that the solar cycle
dependence of the EUV polar corona occurs because of the large-scale
topology of the solar corona and its relationship with the mid-latitude
magnetic flux. It is seen more pronounced on the rising phase of
the solar cycle due to the connectivity of the coronal structures
extended from the mid-latitude to the high-latitude. But, after the
solar cycle maximum the EUV polar corona shows a less dependence of the
mid-latitude corona. In the polar regions the absent of the correlation
of the unsigned magnetic flux and EUV corona occurs not only due to
the effect of projection. But it tells us about the numerous emerging
bi-polar and unipolar regions inside the polar region which does not
contribute to the brightness of the EUV corona. Really, during the
solar minimum when the polar magnetic field reaches its maximum and
number of unipolar magnetic regions of strong magnetic field increases,
we observe dimming and coronal holes instead of the bright EUV corona.
Title: Magnetic and EUV coupling in cycle 23
Authors: Benevolenskaya, Elena
Bibcode: 2008cosp...37..241B
Altcode: 2008cosp.meet..241B
The Extreme Ultraviolet (EUV) corona in solar cycle 23 displays a
strong relationship to the photospheric magnetic activity. For this
studying the EUV data of Extreme Ultraviolet Imaging Telescope and
magnetic data of Michelson Doppler Imager instrument on the bord the
Solar and Heliospheric Observatoty are used. In the presentaion, the
evolution and dynamics of the solar activity as a source of the solar
wind are considered. The results also show an important role of the
magnetic topology in the EUV corona.
Title: Dynamics of the small-scale magnetic field at high latitudes
on the Sun
Authors: Benevolenskaya, Elena
Bibcode: 2008cosp...37..240B
Altcode: 2008cosp.meet..240B
The evolution of the small-scale magnetic field is considered at high
latitudes on the Sun using the Michelson Doppler Imager (MDI) data
from the Solar and Heliospheric Observatory (SOHO) for cycle 23. The
results reveal an influence of the subsurface velocity gradient and
supergranulation on the emerging and dynamics of the small-scale
magnetic field. The highlatitude large-scale magnetic field are
clustered from these small-scale magnetic regions or 'elements' of
dominant polarity and display the solar cycle behavior in spite that
fact that small-scale magnetic regions have a tendency to be present
1-2 day, after that they are replaced by new ones.
Title: High-latitudinal Activity in Solar Cycle 23
Authors: Benevolenskaya, E. E.
Bibcode: 2007AGUFMSH14A1699B
Altcode:
Cycle 23 is going to be finished. What is the new we know about the
nature of the solar cyclicity on the base of the modern observations in
space and on the ground? How deep is our knowledge about the high-(mid)-
latitudinal activity on the Sun? And, it is the next question. Is
our undestanding of the solar activity enough to predict the next
cycle and the behavior of the solar activity in the future. All these
questions come from the past and are still an important. The Solar
and Heliospheric Observatory provides us an important data of coronal
and magnetic activity since 1996 (the beginning of the cycle 23). Due
to these data we can look at the EUV corona on the solar disk and
compare it with the magnetic energy release, directly. We can observe
the changing of the magnetic pattern during the solar cycle from
small-scale magnetic elements ('knots', or facular) to large-scale
(prominances, sunspots) both at the photosphere and the corona. The
results of investigations of the current cycle made by different
authors show the complicated picture of the solar cycle while the main
features like Hale's and Joe's laws, 'butterfly' distibutions, polar
magnetic field reversals are kept. Here, I represent the results of
the investigation of the high-latitudinal activity and its relation to
the mid-latitude of the photoshere and the corona for the current cycle
23 using the SOHO/MDI, SOHO/EIT and WSO solar data. The observational
dynamic behavior of the solar magnetic features is discussed with the
relation to the dynamo theories.
Title: Rotation of the magnetic elements in polar regions on the Sun
Authors: Benevolenskaya, E. E.
Bibcode: 2007AN....328.1016B
Altcode:
Using the Michelson Doppler Imager (MDI) data from Solar and
Heliospheric Observatory (SOHO), the rotation rate of the unipolar
magnetic regions in North high-latitude regions of the Sun is
estimated by tracking individual magnetic elements. The analysis
reveals a strong spin down near the pole, which is greater than the
Doppler and magnetic rotation rates estimated by Snodgrass & Ulrich
(1990), and rotation rate inferred from helioseismology (Birch &
Kosovichev 1998), and is probably related to variation of velocity
gradient in the subsurface shear layer.
Title: Polar magnetic field reversals on the Sun
Authors: Benevolenskaya, Elena E.
Bibcode: 2007HiA....14..273B
Altcode:
The polar magnetic fields on the Sun have been an attractive subject for
solar researches since Babcock measured them in solar cycle 19. One of
the remarkable features of the polar magnetic fields is their reversal
during the maxima of 11-year sunspot cycles. I have present results of
the investigations of the polar magnetic field using SOHO-mdi data. It
is found, that the polar magnetic field reversal is detected with mdi
data for polar region within 78° 88°. The North Pole has changed
polarity in CR1975 (April 2001). The South reversed later in CR1980
(September 2001). The total unsigned magnetic flux does not show the
dramatic decreasing during the polar reversals due to omnipresent
bi-polar small-scale magnetic elements. The observational and
theoretical aspects of the polar magnetic field reversals are discussed.
Title: EUV Corona in Solar Cycle 23
Authors: Benevolenskaya, Elena
Bibcode: 2007AAS...210.9207B
Altcode: 2007BAAS...39R.209B
Extreme-Ultraviolet Telescope (EIT) on board SOHO provides us with
unique data since 1996 up to the present time. The solar corona
in Extreme-Ultraviolet emissions is visible on the solar disk
and demonstrates a good relationship with the magnetic activity
(SOHO/MDI and NSO/Kitt Peak data). We have analysed the EUV
data from SOHO/EIT in four wavelengths (171A, 195A, 284A, and 304A),
and constructed coronal synoptic maps for 1996-2006. This period
practically covers the whole current cycle. The synoptic structure
of the solar corona reveals significant changes in the coronal and
magnetic topology during the cycle. These studies support an
idea about the important role of the solar corona in solar cycle. The
magnetic energy release in the corona together with dynamo processes
in the convective zone and in the photosphere (differential rotation,
diffusivity and meridional circulation) are the parts of a common
process, which produces the solar activity cycle.
Title: MHD Simulation of The Solar Corona Using The Synchronic Frame
Format of The Solar Magnetic Field and The EIT-based Temperature Map
Authors: Hayashi, Keiji; Zhao, X.; Benevolenskaya, E.; Liu, Y.
Bibcode: 2007AAS...210.9106H
Altcode: 2007BAAS...39..205H
The quasi-steady states of the three-dimensional global solar corona
obtained with the time-dependent MHD simulation are presented. The
synchronic frame format of solar magnetic field and the SOHO/EIT-based
coronal temperature map are used as the boundary constraints, so that
the pressure balance between the coronal plasma and magnetic field will
be realistically simulated and thus the obtained three-dimensional
simulation data will better represent the structures of the solar
coronal at the time of interest. Our MHD code employs the concept
of the projected normal characteristic method to include these
measurement-based data as the sub-Alfvenic numerical boundary conditions
without numerical instability.
Title: EUV coronal pattern of complexes of solar activity
Authors: Benevolenskaya, Elena E.
Bibcode: 2007AdSpR..39.1860B
Altcode:
Studying of the coronal plasma associated with long-lived complexes
of the solar activity is important for understanding a relationship
between the magnetic activity and the solar corona changing during the
solar cycle. In the present paper, two long-lived complexes of the solar
activity at the beginning of the current solar cycle 23 are investigated
by using the Extreme-Ultraviolet data (EUV) from SOHO/EIT. For this
purpose the EIT limb synoptic maps during the CR1916-CR1919 (11 November
1996-1 March 1997) are obtained. The coronal temperature structures
derived from the three lines 171A (Fe IX,X), 195A (Fe XII)and 284A
(Fe XV) are investigated by applying an algorithm developed by Zhang et
al. [Zhang, J., White, S.M., Kundu, M.R. ApJ 527, 977, 1999]. Standard
EIT software are used for the temperature estimation from the ratio of
two lines of Fe IX,X and Fe XII. The method of the rotational tomography
with a correction for an inclination of the Earth's orbit (B-angle)
to the helioequator is applied to obtain the three-dimensional (3-D)
coronal structure of the complex of the solar activity. The results
reveal difference in temperature structures related to multi-poles
magnetic structures of the complex of solar activity and to the typical,
the bipolar activity complex.
Title: Solar X-ray and EUV corona and their relation to the magnetic
activity
Authors: Benevolenskaya, Elena E.
Bibcode: 2007AdSpR..39.1491B
Altcode:
We have studied the solar magnetic cycle in corona using X-ray data
from YOHKOH and Extreme Ultraviolet data from SOHO/EIT. Soft X-ray data
last the period from after the maximum cycle 22 to the maximum cycle 23
(1991-2001). The SOHO/EIT Extreme Ultraviolet data are used for the
period from 1996 to 2003. These data provide us a unique opportunity
to look at the solar corona on the solar disc and to compare with the
magnetic activity, directly. Our studies reveal a close relationship
between the coronal emissions and the photospheric magnetic field in
the axisymmetrical case. The evolution of coronal structures in X-ray
and EUV can be considered as a proxy of the coronal magnetic field and
demonstrates a development of the solar magnetic cycle in corona. It
is shown that the most important feature of the coronal cycle is the
forming of giant loops structure visible in X-ray and, partially,
in EUV (284A) on the solar disk.
Title: MHD Simulation of the Global Solar Corona Using the Synoptic
Frame of the Photospheric Magnetic Field and Coronal-Base Temperature
Authors: Hayashi, K.; Zhao, X.; Benevolenskaya, E.
Bibcode: 2006AGUFMSH23B0351H
Altcode:
The solar surface boundary map plays an essential role in determining
the results of the MHD simulation of the global solar corona and
solar wind. In this work, we will present the MHD simulation using
the synoptic frame format of the solar photospheric magnetic field and
coronal-base temperature. The concept of synoptic frame is developed
for the global map to contain both the long-term global components and
the newly measured components. The synoptic frame is developed by Zhao
et al. [1999] originally for the photospheric magnetic field. Recent
improvements [Zhao et al., 2006] allow taking into account the
differential rotation. Using the boundary map in this format as the
boundary condition of the MHD simulation, we can now specify the
time to be simulated more adequately. Recently Hayashi et al. [2006]
simulated the global corona using the temperature map obtained from
the analysis of the SOHO/EIT data and found that the coronal-based
temperature is one of the decisive factors of the solar corona. We used
the CHIANTI software to derive the coronal temperature. Combining these
two features, we can specify both the magnetic field and temperature
at a particular time and simulate the global solar corona more
realistically. The three-dimensional solar coronal quantities simulated
in this way are compared with observations, such as the shape of the
coronal hole and the plasma quantities of the solar coronal streamers.
Title: Cycle in solar polar activity
Authors: Benevolenskaya, E. E.
Bibcode: 2006AGUFMSH21A0328B
Altcode:
Solar polar activity is dominated by small-scale magnetic elements. The
most of them of dominant polarity are coincided with polar faculae. It
is known that number of the polar faculae change during the solar
cycle and reach their maxima at Sunspot minimum. But, the solar polar
regions display the bi-polar magnetic pattern. Here, it is presented
the results of the investigations of the polar magnetic elements during
the solar cycle and their role in polar magnetic field reversals. The
SOHO/MDI data are analyzed in form of the high-resolution synoptic
maps for periods close to the maximum of B-angle for South and North
poles. The dynamics of the small scale elements shows the changing of
the polarity in the distribution of small scale elements during the
polar magnetic field reversals.
Title: Polar magnetic field reversal.
Authors: Benevolenskaya, E. E.
Bibcode: 2006IAUJD...8E..54B
Altcode:
The polar magnetic fields on the Sun have been an attractive subject
for solar researches since Babcocks measured them in solar cycle 19
(Babcock and Babcock, 1955). One of the remarkable features of the polar
magnetic fields is their reversal during the maxima of 11-year sunspot
cycles (Babcock and Livingston, 1958; Babcock, 1959). I have present
results of the investigations of the polar magnetic field using MDI
data. It is found, that the polar magnetic field reversal is detected
with SOHO/MDI data for polar region within 78deg - 88deg. The North
Pole has changed polarity in CR1975 (April 2001). The South reversed
later in CR1980 (September 2001). The total unsigned magnetic flux
does not show the dramatic decreasing during the polar reversals due
to omnipresent bi-polar small-scale magnetic elements (Severnyi 1965,
Lin et al. 1994, Benevolenskaya 2004). The observational and theoretical
aspects of the polar magnetic field reversals are discussed. References
Babcock, H. W., and Babcock, H. D. 1955, ApJ, 121, 349 Babcock, H. W.,
Livingston W. C., 1958, Science, 127, 1058 Babcock, H. D., 1959, ApJ,
130, 364 Benevolenskaya, E. E. 2004, Astron. Astrophys., 428, L5 Lin,
H., Varsik, J., Zirin, H., 1994, Solar Phys., 155, 243 Severnyi A. B.,
1965, Soviet Astron. Letters, 9, 171
Title: The Sun's Polar Magnetic Flux from 1996-2006 Observed With
SOHO/MDI
Authors: Hoeksema, Jon T.; Benevolenskaya, E. E.; Liu, Y.; Scherrer,
P. H.; Zhao, X.
Bibcode: 2006SPD....37.0702H
Altcode: 2006BAAS...38..228H
Observations of the Sun's magnetic field using nearly 10 years of
full-disk SOHO/MDI data are used to investigate the net flux and total
flux of the polar regions.The northern pole above 78 degrees changed
polarity in April 2001 (CR 1974), five rotations before the southern
pole (August, 2001, CR 1979). These dates are a little earlier than
those found by Durrant and Wilson (2003): CR 1975 in the north and CR
1981 in the south.Solar cycle changes in the total polar magnetic flux
are more difficult to determine. Most of the polar measurements are
near the noise level due to the extreme reduction in the line-of-sight
component due to projection effects near the limb. Determination of the
total flux is highly sensitive to changes in noise due to the different
MDI observing modes, to systematic errors in the instrument, and to
the exact method of processing the data (e.g. spatial and temporal
averaging). Periodic orientation changes of the SOHO spacecraft
in recent years allow better characterization of the systematic
errors. Observations taken at different inclinations of the solar
rotation axis also help characterize the known errors to provide a
better estimate of the solar polar flux with time.
Title: Is the solar cycle still a puzzle?
Authors: Benevolenskaya, Elena E.
Bibcode: 2006IAUS..233..215B
Altcode:
The solar magnetic cycle affects all levels of the Sun including
the convection zone, photosphere, chromosphere and corona. Recent
advances in solar space missions (Yohkoh, SOHO and others) and,
also, ground-based observations provide us an excellent opportunity
to investigate solar magnetic activity in detail, and to draw a new
picture of the solar magnetic cycle. Magnetic field appears on the solar
surface as a result dynamo processes in the convection zone, and forms
bipolar complexes of solar activity. These complexes can be seen in the
photosphere as dark sunspots surrounded by the bright plages extended
into chromosphere, with arcades of coronal loops best observed in EUV
and soft X-rays. The coronal loops reflect the large-scale magnetic
structure of complexes of activity. The new data reveal fundamental
changes in the magnetic topology during the solar cycle, and details
of the polar magnetic field reversals occurring near the sunspot
maximum. The solar synoptic maps obtained from the photospheric
and coronal data display a close correlation between the erupted
magnetic flux and coronal emissions and show large-scale magnetic
connectivities. The brief review of solar cycle studies is presented.
Title: EUV coronal pattern of complexes of solar activity
Authors: Benevolenskaya, E.
Bibcode: 2006cosp...36.2584B
Altcode: 2006cosp.meet.2584B
The studying of the pattern of the coronal plasma surrounded the
complexes of solar activity on the different phase of the solar cycle
represents a great deal of interest The results of the investigation
of the coronal structures above the complexes of solar activity are
presented The coronal structures are reconstructed from the EUV limb
synoptic maps in three lines 171A 195A and 284A by the method of
rotational tomography using SOHO EIT data Results also reveal the
connectivity among the multi-temperature structure related to the
multi-poles parts of the complex of solar activity
Title: High-latitude and small scale magnetic field during the
solar cycle.
Authors: Benevolenskaya, E.
Bibcode: 2006cosp...36.2580B
Altcode: 2006cosp.meet.2580B
There are different types of small scale magnetic fields on the
Sun so-called magnetic carpet ephemetic regions and polar magnetic
facular The question arises how much they contribute to the magnetic
flux to compare with the complexes of solar activity during the solar
cycle Evolution of the small scale elements is an important problem
in relation to the problem of the solar cycle nature The studying of
the evolution of the small scale magnetic field during the current
solar is represented The possible mechanism of the solar magnetic
field generation is discussed
Title: Three-Dimensional Magnetohydrodynamic Simulation of a Global
Solar Corona Using a Temperature Distribution Map Obtained from SOHO
EIT Measurements
Authors: Hayashi, Keiji; Benevolenskaya, Elena; Hoeksema, Todd; Liu,
Yang; Zhao, Xue Pu
Bibcode: 2006ApJ...636L.165H
Altcode:
The temperature at the base of the solar corona is one of the important
factors in determining the solar coronal structure. In this Letter,
we performed the time-dependent magnetohydrodynamic (MHD) simulation
for the solar corona utilizing the temperature map derived from the
multiwavelength observation by the EUV Imaging Telescope (EIT) on
the Solar and Heliospheric Observatory (SOHO) and the magnetic field
map from the Michelson Doppler Imager (MDI) on SOHO. We analyzed the
difference in three-dimensional magnetic field topology obtained when
the uniform base temperature adopted in standard simulations is replaced
by the observation-based, nonuniform temperature distribution. The
differences in the magnetic field topology obtained as the response of
the solar corona to the changes of the temperature at the coronal base
depict the role of the plasma conditions at the coronal base in the
dynamics of the global solar corona. This work is our first effort to
utilize the data of the solar coronal plasma as the boundary condition
to enhance the MHD simulations of a solar corona.
Title: The Formation and Evolution of Complexes of Activity, Activity
Nests and the Large-scale Connectivity in the Solar Corona
Authors: Benevolenskaya, E. E.
Bibcode: 2005ASPC..346..129B
Altcode:
The historical review of the investigations of the formation and
evolution of the complexes of solar activity is presented. The old
data (sunspot and magnetic field distributions) and the new data of
YOHKOH and SOHO space mission display the whole picture of the solar
activity at different levels (photosphere, transition region and
corona). They reveal large-scale connectivity within the complexes of
solar activity and display the evolution of large-scale magnetic field
in corona during the solar cycles. Carrington was first who (1863)
introduced the latitude-longitude coordinate system and suspected that
sunspots were not distributed randomly over solar longitudes. This
phenomenon was confirmed by many other observers who used the term
Active longitudes or Active longitudinal zones, or Activity nests to
describe the longitudinal zones where large sunspots (greater than 500
microhemispheres) tend to reappear during long periods of more than
several years (Vitinskii, 1982). Nowadays, several different terms
are used for describing non-uniform longitudinal distributions of the
solar activity. Usually, the active longitudes are explained by the
existence of the non-axisymmetrical magnetic field which has roots in
the interior of the sun. The non-axisymmetrical magnetic field appears
to be at photosphere, corona and heliosphere. In the heliosphere we
observe the well-known sector structure of the interplanetary magnetic
field as a consequence of the solar non-axisymmetrical magnetic field.
Title: Characteristics of the Sun's polar magnetic flux from 1996-2005
using SOHO/MDI observations
Authors: Benevolenskaya, E. E.; Hoeksema, J. T.; Liu, Y.; Zhao, X.;
Scherrer, P. H.
Bibcode: 2005AGUFMSH41A1120B
Altcode:
We have studied the Sun's polar magnetic field using nearly 10 years
of full-disk SOHO/MDI data. We have estimated the time of the polar
magnetic field reversals above 78 degrees. The net flux in the southern
cap changed polarity in CR 1979 (August, 2001), five rotations later
than the north (CR 1974; April, 2001). These are just a little earlier
than the times identified by Durrant and Wilson (2003): CR 1981 in
the south and CR 1975 in the north. We also investigate apparent
solar cycle changes in the total magnetic flux observed in the polar
caps. The total flux determination is highly sensitive to changes in
random noise due to the different MDI observing modes, to systematic
errors in the instrument, and to the exact method of processing the
data (e.g. spatial and temporal averaging). This is because nearly all
of the flux measurements are near the noise level due to the extreme
reduction in the line-of-sight component due to projection effects
near the limb. In recent years the SOHO spacecraft has periodically
been rotated and this allows us to better characterize the systematic
errors. Using observations taken when the inclination of the solar
equator provides the best viewing of each pole, we correct for all known
errors to provide the best estimate of the solar polar flux with time.
Title: 3-D structure of the complexes of solar activity
Authors: Benevolenskaya, E. E.
Bibcode: 2005AGUSMSH13A..02B
Altcode:
The typical complex of the solar activity persists on all levels of the
solar atmosphere and consists of sunspots and surrounding plages in
photosphere and chromosphere with arcades of loops visible in corona
in Extreme Ultraviolet Emission and Soft X-ray. These coronal loops
are the tracers of the lines of the magnetic field strength connected
the magnetic areas with opposite polarities because of the complexes
of solar activity are bipolar. The results of investigations of
the evolution and the topology of the long-lived complexes of solar
activity using SOHO/MDI and SOHO/EIT data for the period from 1996
to 2004 years are presented . We are discussing the nature of the
existence of the long-lived complexes of solar activity.
Title: Multi-Wavelength Investigations of Solar Activity (IAU S223)
Authors: Stepanov, Alexander V.; Benevolenskaya, Elena E.; Kosovichev,
Alexander G.
Bibcode: 2005misa.book.....S
Altcode:
Section I: Solar Cycle in the Interior, Atmosphere and Heliosphere;
Section II-III: Structure and Evolution of Active Regions from the
Sub-Photospheric Layers to the Corona, Filaments and Prominences;
Section IV: Multi-Scale Coronal Structures and Links to Photospheric
Magnetic Field; Section V: Energy Transport, Storage and Release in
the Solar Atmosphere and Corona; Section VI: Heliospheric Effects and
Space Weather Research; Section VII: Multi-Wavelength Observations of
the Sun from Ground and Space.
Title: Polar magnetic flux on the Sun in 1996-2003 from SOHO/MDI data
Authors: Benevolenskaya, E. E.
Bibcode: 2004A&A...428L...5B
Altcode:
Polarity of the polar magnetic fields on the Sun changes in every
11-year sunspot cycle, affecting the large-scale structure of the
corona and heliosphere. Using the SOHO/MDI data, the flux of the radial
component of the magnetic field is estimated for different latitudinal
zones. It is estimated that the total magnetic flux of the Northern
polar zone, from 78° to 88°, is about 1.5-1.7
× 1022 Mx, and it is about 2.3-2.5× 1022 Mx
in the similar Southern polar zone. The new data reveal an interesting
result that the total polar magnetic fluxes do not vary significantly
during the polar magnetic field reversals in both hemispheres, while
the positive and negative parts of the total fluxes do change.
Title: Longitudinal Structure of Solar cycle 23
Authors: Benevolenskaya, E. E.
Bibcode: 2004AGUFMSH13A1145B
Altcode:
The non-axisymmetrical pattern of solar activity during the 1996-2004
years has been studied using the SOHO/MDI, SOHO/EIT and WSO data. These
data reveal close correlation between the non-axisymmetrical magnetic
field and coronal structures. The long-lived complexees of solar
activity have clusterred in preferred (active) longitudes and have
shown an impulsive nature of the solar cycle. The nature of active
longitudes or active longotudinal zones is discussed.
Title: Multi-wavelength investigations of solar activity : proceedings
of the 223th symposium of the International Astronomical Union held
in Saint Petersburg, Russia, June 14-19, 2004
Authors: Stepanov, Alexander V.; Benevolenskaya, Elena E.; Kosovichev,
Alexander G.
Bibcode: 2004IAUS..223.....S
Altcode: 2005IAUS..223.....S
No abstract at ADS
Title: Solar Cycle in Photosphere and Corona
Authors: Benevolenskaya, Elena E.
Bibcode: 2004IAUS..223...33B
Altcode: 2005IAUS..223...33B
The solar cycle in photosphere and corona reflects the internal dynamics
on the Sun. According to the modern understanding the observed behavior
of solar activity is related to the dynamo process in convection zone
and photosphere and it is closely connected with the evolution of
the coronal structures. The observational data from ground and space
allow us to investigate the solar cycle as a complex phenomenon and
to clarify the most important features such as polar magnetic field
reversals, non-uniform distributions of the solar activity complexes
and fine structure of the solar cycle.
Title: Polar magnetic flux from SOHO/MDI data
Authors: Benevolenskaya, E. E.
Bibcode: 2004IAUS..223...87B
Altcode: 2005IAUS..223...87B
No abstract at ADS
Title: Solar X-ray and EUV corona and their relation to the magnetic
activity
Authors: Benevolenskaya, E.
Bibcode: 2004cosp...35.2085B
Altcode: 2004cosp.meet.2085B
We have studied the solar magnetic cycle in corona using X-ray data from
YOHKOH spacecraft. These data last the period from after the maximum
cycle 22 to the maximum cycle 23 (1991-2001). We have also considered
the SOHO/EIT data. The Extreme Ultraviolet data display an evolution of
the coronal structures in cycle 23 (1996-2003). These studies reveal
a close relation of the coronal X-ray and the EUV emissions to the
photospheric magnetic field. The evolution of coronal structures in
X-ray and EUV can be considered as a proxy of the coronal magnetic
field and demonstrates a development of the solar magnetic cycle in
corona. It is shown that the most important feature of the coronal
cycle is the forming of giant loops structure visible in X-ray and,
partially, in EUV (284A) on the solar disk. The structure of X-ray
and EUV corona on the Sun are discussed.
Title: Polar magnetic field and impulses of solar activity.
Authors: Benevolenskaya, E.
Bibcode: 2004cosp...35.2089B
Altcode: 2004cosp.meet.2089B
Polar magnetic field on the Sun has been changing their polarity every
11th year sunspot cycle. We have presented the results of analysis
the polar magnetic field and their relation to mid-latitude 'impulses
of solar activity' in 1996-2003. Using the SOHO/MDI data the flux of
radial component of the magnetic field has been estimated for different
latitudinal zones. It is found that the magnetic flux for north polar
zone (from 78deg to 88deg) equals to about 1.5-1.7 x 10^22 Mx and
it is about 2.3-2.5 x 10^22 Mx for south polar zone (from -88deg to
-78deg). It is also revealed that the polar magnetic flux does not show
any significant variations during the polar magnetic field reversals in
both hemispheres, while the positive and negative parts of the magnetic
flux do changing. For mid and low latitude regions the situation has
been changing. Magnetic flux shows the solar cycle dependence and
manifests 'impulses of solar activity'. The evolution of the polar
magnetic field, magnetic flux at the photosphere and their relation
to the coronal structures during the solar cycle are discussed, also.
Title: Polar Coronal and Magnetic Activity in Solar Cycle 23
Authors: Benevolenskaya, E. E.
Bibcode: 2003AGUFMSH42B0531B
Altcode:
The results of investigation of the polar coronal activity using
EUV data from SOHO/EIT and its relations to the magnetic activity
studied from SOHO/MDI for 1996-2002 are presented. The observations of
formation and evolution of polar coronal structures during the current
activity cycle reveal close correlations between eruptive magnetic
flux, coronal topology and changes of the global magnetic field,
which have interesting implications for understanding the mechanism
of the solar cycle.
Title: Impulses of activity and the Solar cycle
Authors: Benevolenskaya, Elena E.
Bibcode: 2003SoPh..216..325B
Altcode:
Extreme-ultraviolet data from EIT/SOHO (1996-2002), soft X-ray
data from Yohkoh (1991-2001), and magnetic field data from MDI/SOHO
(1996-2002) and Kitt Peak Observatory, NSO/NOAO (1991-2002) are analyzed
together in the form of synoptic maps for the investigation of solar
cycle variations of the corona and their relation to the magnetic
field. These results show new interesting relations between the
evolution of the topological structure of the corona, coronal heating
and the large-scale magnetic field. The long-lived coronal structures
are related to complexes of solar activity and display quasi-periodic
behavior (in the form of impulses of coronal activity) with periods
of 1.0-1.5 year, in the axisymmetric distribution of EUV and X-ray
fluxes during the current solar cycle 23. In particular, during the
second maximum of this cycle the solar corona became somewhat hotter
than it was in the period of the first maximum.
Title: Impulsive Nature of Solar Cycle
Authors: Benevolenskaya, E. E.
Bibcode: 2003SPD....34.1901B
Altcode: 2003BAAS...35Q.842B
Extreme-Ultraviolet data from EIT/SOHO (1996-2002 years), soft X-ray
data from YOHKOH (1991-2001), and magnetic field data from MDI/SOHO
(1996-2002 years) and Kitt Peak Observatory (1991-2002) are analyzed
together in the form of synoptic maps for the investigation of solar
cycle variations of the corona and magnetic field. These results
show new interesting relations between the evolution of topological
structure of the corona, coronal heating and the large-scale magnetic
field. The long-living coronal structures are related to complexes
of solar activity and display the quasiperiodic behavior (impulses of
coronal activity) with periods of 1.0-1.5 year in the axisymmetrical
distribution of EUV and X-ray fluxes during the current solar cycle
23. In particular, during the second maximum of the cycle 23 corona
became somewhat hotter than in the period of the first maximum.
Title: Evolution of Large-scale Coronal Structure with the Solar
Cycle from EUV Data
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2002ASPC..277..419B
Altcode: 2002sccx.conf..419B
No abstract at ADS
Title: Solar cycle in the photosphere and corona
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2002ESASP.506..831B
Altcode: 2002svco.conf..831B; 2002ESPM...10..831B
EIT/SOHO data in four EUV lines and MDI/SOHO (1996-2002), and soft X-ray
YOHKOH data (1991-2001) are analyzed in the form of coronal synoptic
maps for the investigation of solar cycle variations of the corona
and magnetic field. The evolution of coronal structures is closely
related to sunspot activity, photospheric magnetic field, and topology
of the large-scale magnetic field. The coronal structures visible in
extreme ultraviolet and soft X-rays as extended bright loops, reflect
the non-axisymmetrical magnetic structure of the Sun, changing with the
solar cycle. The long-living coronal structures are related to complexes
of solar activity and display the quasiperiodic behavior (impulses of
coronal activity) with periods of 1.0-1.5 year in the axisymmetrical
distribution of EUV and X-ray fluxes during the current cycle.
Title: Impulses of Coronal Activity and Their Relation to the
Solar Cycle
Authors: Benevolenskaya, E. E.
Bibcode: 2002AGUFMSH21A0512B
Altcode:
SOHO/EIT Extreme Ultraviolet and YOHKOH soft X-ray data have revealed
the close relation between the coronal structures and the photospheric
magnetic flux. These data can be considered as a proxy of magnetic field
structures in the corona. During the beginning of the solar cycle the
evolution of the coronal structures and, therefore, the topological
changes of the magnetic field reveal a quasiperiodical process of
'impulses of coronal activity' with a period of approximately 1-1.5
years. This process is represented by the evolution of giant coronal
loops of hot plasma (2-3 MK), or by closed lines of magnetic field,
which connect the following parts of the complexes of the sunspot
activity with the solar polar regions (predominantly of the opposite
polarity). The 'impulses of coronal activity' are correlated with the
erupted magnetic flux in the mid-latitudinal zones, and they display
non-uniform distributions with longitude. Therefore, the 'impulses'
mostly reflect the non-axisymmetrical component of the solar magnetic
field. The quasiperiodic behavior of the 'impulses' results from the
characteristic lifetime and reappearance of the sunspot complexes in
active longitudinal zones (active longitudes). We discuss the physical
nature of the 'impulses of coronal activity' and their possible
relations to the dynamo process.
Title: Coronal structures in extreme ultraviolet and soft X-rays,
and their relation to the photospheric magnetic flux
Authors: Benevolenskaya, E. E.
Bibcode: 2002ESASP.505..353B
Altcode: 2002solm.conf..353B; 2002IAUCo.188..353B
The EIT/SOHO data in four EUV lines (1996-2001 yrs) and soft
X-ray YOHKOH data (1991-2001 yrs) were analyzed in the form of
coronal synoptic maps. Two types of the bright structures have been
detected. The structures of the first type migrate equatorward as
the solar cycle progresses. They are related to complexes of sunspot
activity and display a "butterfly"-type distribution. The structures of
the second type migrate polarward and are associated with footpoints of
giant coronal loops in EUV, which magnetically couple the polar regions
and the following parts of the active complexes. These structures of
coronal activity are also pronounced in the soft X-ray maps. However,
the whole structure of the giant polar loops is visible in X-rays,
and reveal connections to the mid-latitude coronal structures. These
structures appear during the rising phase of the solar cycle and its
maximum, and show quasiperiodic impulsive variations with 1-1.5-year
period. For the low- and mid-latitude structures we have studied the
relationship between the soft X-ray intensity and the photospheric
magnetic flux and found that it can be represented by the power
law. However, the power index is higher for the period of the
declining phase and minimum of solar activity than for its rising
phase and maximum. This indicates that coronal heating has different
characteristics at different phases of the solar cycle, and depends not
only on the magnetic flux, but probably also on structural properties
of the magnetic field.
Title: Large-Scale Solar Coronal Structures in Soft X-Rays and Their
Relationship to the Magnetic Flux
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Lemen, J. R.;
Scherrer, P. H.; Slater, G. L.
Bibcode: 2002ApJ...571L.181B
Altcode:
We have investigated the relationship between magnetic activity
and coronal structures using soft X-ray data from the Yohkoh soft
X-ray telescope and magnetic field data from the Kitt Peak Solar
Observatory for the period of 1991-2001 and EUV data from the Solar
and Heliospheric Observatory EUV Imaging Telescope for 1996-2001. The
data are reduced to Carrington synoptic maps, which reveal two types of
migrating structures of coronal activity at low and high latitudes in
the time-latitudinal distribution. The low-latitude coronal structures,
migrating equatorward, correspond to photospheric sunspot activity,
and the high-latitude structures migrating toward the poles reflect
polar activity of the Sun. We present the following new results:1. The
migrating high-latitude coronal magnetic structures are revealed in the
soft X-ray data as complete bright giant loops connecting the magnetic
field of the following part of active regions with the polar field. They
appear during the rising phase and maximum of the solar cycle and show
quasi-periodic impulsive variations with a 1-1.5 yr period.2. The soft
X-ray intensity of these loops has a strong power-law correlation with
the photospheric magnetic flux. The power-law index, which on average
is close to 2, shows variations with the solar cycle: it is higher
for the period of the declining phase and minimum of solar activity
than for the rising phase and maximum.
Title: Large-scale coronal structures in EUV and soft X-rays in
solar cycle 23
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.;
Lemen, J. R.; Slater, G. L.
Bibcode: 2002ESASP.508..367B
Altcode: 2002soho...11..367B
We have analyzed the EIT/SOHO data in four EUV lines (171 Å, 195 Å,
284 Å and 304 Å) and soft X-ray YOHKOH data in two filters (AlMg and
Al) in the form of coronal synoptic maps for the period 1996 - 2001
yrs. Two types of the bright structures have been detected in EUV in
the axisymmetrically averaged synoptic maps. The structures of the first
type migrate equatorward as the solar cycle progresses. They are related
to complexes of sunspot activity and display the "butterfly"-type
distribution. The structures of the second type migrate polarward
and are associated with footpoints of giant coronal loops, which
connect the polar regions and the following parts of the active
complexes. These structures of coronal activity are also pronounced in
the soft X-ray maps. However, the whole structure of the giant polar
loops is visible in X-rays, and reveals connections to the low-latitude
coronal structures. The relationship between the soft X-rays emission
and the photospheric magnetic flux obtained from SOHO/MDI and Kitt
Peak Solar Observatory has been investigated. It has been found that
the relationship depends on the phase of the solar cycle. We discuss
the role of the magnetic flux in the formation and evolution of the
stable coronal structures during the rising phase of cycle 23.
Title: Solar cycle variations in corona
Authors: Benevolenskaya, E. E.
Bibcode: 2002AAS...200.5712B
Altcode: 2002BAAS...34..738B
Six years of EIT/SOHO data in four EUV lines (1996-2001) and ten
years of soft X-ray YOHKOH data (1991-2001) are analyzed in the
form of coronal synoptic maps for the investigation of solar cycle
variations of the corona. The evolution of coronal structures is
closely related to sunspot activity, photospheric magnetic field,
and topology of the large-scale magnetic field. The coronal structures
visible in extreme ultraviolet and soft X-ray as extended bright loops
reflect the non-axisymmetrical magnetic structure of the Sun changing
with solar cycle. The long-living coronal structures are related to
complexes of solar activity and display the quasiperiodic behavior
('impulses' of coronal activity) with periods of 1.0-1.5 year in
the axisymmetrical distribution of EUV and X-ray fluxes during the
current cycle. There is a close correlation between the soft X-ray
intensity and photospheric magnetic flux in mid-latitudinal zones,
which can be represented by the power law. The power index is higher
for the period of the declining phase and minimum of solar activity
than for its rising phase and maximum. This indicates that coronal
heating may have different characteristics at different phases of the
solar cycle, and depends not only on the magnetic flux, but probably
also on structural properties of the magnetic field.
Title: Non-axisymmetrical distributions of solar magnetic activity
and irradiance
Authors: Benevolenskaya, E. E.
Bibcode: 2002AdSpR..29.1941B
Altcode:
Active longitudes play an important role in spatial organization
of solar activity. These zones associated with complexes of solar
activity may persist for 20-40 consecutive rotations, and may be caused
by large-scale non-axisymmetrical components of the global magnetic
field. These zones of the field concentrations are 20°-40° wide and
during subsequent rotations tend to reappear at constant longitude or
drift slightly eastward or westward. Since the magnetic field is the
principle source of the variations of radiation on the solar surface
the active longitudes affect the solar irradiance received at the
Earth. In this paper I study connections between the active longitudes
and irradiance variations using VIRGO/SOHO, KPO and WSO data, which
covered the transition period from solar cycle 22 to cycle 23 and rising
phase of cycle 23. The result of this investigation is that active
longitudes are associated with increases of the total solar irradiance
and are prime sources of enhanced EUV radiation and coronal heating.
Title: Coronal Patterns of Activity from Yohkoh and SOHO/EIT Data
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.;
Lemen, J. R.; Slater, G. L.
Bibcode: 2002mwoc.conf..329B
Altcode:
We have studied the evolution of large-scale coronal structures using
soft X-ray data from YOHKOH and EUV data from SOHO/EIT during the
rising phase of the current solar cycle 23, and compared with the
evolution of the photospheric magnetic field. During this period the
distribution of the coronal structures generally reflects the evolution
of the magnetic fields. However, the data from EIT and YOHKOH reveal
large-scale magnetic connections in the corona which probably play
significant role in the solar cycle. In particular, we have found that
coronal structures such as high-latitude giant loops may be important
for the topological evolution of magnetic structures during the solar
cycle and for polar magnetic field reversals. We discuss possible
mechanisms of the polar magnetic field reversals and their relations
to the observed coronal structures.
Title: Solar Coronal Activity and Evolution of the Magnetic Field
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2002stma.conf...27B
Altcode:
No abstract at ADS
Title: Active longitudes and coronal structures during the rising
phase of the solar cycle
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2002AdSpR..29..389B
Altcode:
The longitudinal structure of the solar corona has been investigated
during the transition period between solar cycles 22 and 23 and at the
beginning of the current cycle 23 using the SOHO/EIT data obtained
in 171 Å, 195 Å, 284 Å and 304 Å EUV lines. The EIT images
were transformed into synoptic maps for each of the spectral lines,
and for the 195Å/171Å line ratio, which is an index of the coronal
temperature. The synoptic maps reveal stable longitudinal structures in
the coronal intensities and temperature, that are related to large-scale
magnetic field structures. We discuss the relation between the coronal
and photospheric magnetic structures obtained from the SOHO and Kitt
Peak Solar Observatory data, and compare the rotation rates of these
structures with the rotation profile of the solar interior in order
to determine the possible origin of the coronal structures.
Title: Solar Coronal Structures in Extreme Ultraviolet and Soft
X-rays and Their Relation to Magnetic Flux
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Lemen, J. R.;
Scherrer, P. H.; Slater, G. L.
Bibcode: 2001AGUFMSH11C0720B
Altcode:
The large-scale coronal structures are ultimately related to internal
magnetic fields and thus provide important information about the solar
dynamo. We have investigated the relationship between magnetic activity
and coronal structures using EUV data from SOHO/EIT and X-ray data
from Yohkoh/SXT, and magnetic field data from Kitt Peak and Wilcox
Solar Observatories for the period 1996-2000 years. We discuss the
non-uniform distribution of coronal heating and its connection with
long-lived complexes of solar activity during the current cycle. EUV
images reveal two sets of migrating structures of coronal activity
in the time-latitudinal distribution of the EUV intensity in 171A,
195A, 284A and 304A EIT wavelength channels. The low-latitude coronal
structures, migrating equatorward, correspond to photospheric sunspot
activity, and the high-latitude structures migrating towards the poles
reflect polar activity of the sun. The polar branches are cooler then
the equatorial branches. This is reflected in the time-latitudinal
distribution of the soft X-rays in two filters (Al and AlMg). We
discuss the physical properties and nature of these structures of
coronal activity and their role in the solar cycle.
Title: Detection of High-Latitude Waves of Solar Coronal Activity in
Extreme-Ultraviolet Data from the Solar and Heliospheric Observatory
EUV Imaging Telescope
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2001ApJ...554L.107B
Altcode:
We present the results of an investigation of EUV coronal structures
in 1996-2000 using the Solar and Heliospheric Observatory EIT data
in 171, 195, 284, and 304 Å lines. During this period, poleward-
and equatorward-migrating waves of solar activity have been found
in axisymmetrical distributions of EUV intensity in all four
lines. In the axisymmetrical distribution of the ratio of 195 Å
to 171 Å intensities, which is a proxy of coronal temperature from
1×106 to 2×106 K, the polar branches are less
prominent. The high-latitude activity waves are caused by giant coronal
magnetic loops connecting the polar magnetic field (formed during the
preceding solar cycle) with the magnetic field of the ``following''
parts of active regions that emerged during the rising phase of the
current cycle. We suggest that these coronal loops play an important
role in the topological evolution of the magnetic structure of the
Sun during the solar cycle.
Title: Polar Activity Wave in the Solar Corona
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2001AGUSM..SP61A05B
Altcode:
We present the results of investigation of EUV coronal structures in
1996-2000 using SOHO/EIT data in 171A, 195A, 284A and 304A. During
this period polarward and equatorward migrating waves of activity
have been found in axysymmetrical distributions of EUV intensity in
all four lines. In the ratio of 195A and 171A intensities, which is
a proxy of coronal temperature from 1 MK to 2 MK, the polar branch
is not present. We discuss the physical nature of the polar wave
of activity and conclude that it is related to dense plasma loops
which are cooler then the loops related to the equatorward migrating
wave. The latter reflects coronal structures connected with active
regions and complexies of solar activity. The polar activity wave
is caused by reconnection between the polar magnetic field and the
magnetic field of `following' parts of active regions, and, probably,
plays an important role in the solar cycle.
Title: Large-Scale Patterns of Solar Magnetic Field and Activity
Cycles
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2001ASPC..248..135B
Altcode: 2001mfah.conf..135B
No abstract at ADS
Title: Active Longitudinal Structures of the Sun from MDI and EIT
Observations
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2001IAUS..203..251B
Altcode:
Using data from the EIT and MDI instruments on SOHO and from Kitt
Peak Observatory we have studied the non-axisymmetrical structure
and dynamics of solar activity at different levels of the solar
atmosphere. The data were reduced to synoptic maps of the photospheric
magnetic field and coronal structures in the EUV lines: 171Å, 195Å,
284Å, and 304Å. In addition, the coronal temperature maps were
obtained using the ration of the 171Å and 195Å lines. The results
reveal long-living longitudinal structures in the photosphere and
corona during the transition from Cycle 22 to 23 and the rising
phase of Cycle 23. We have found the Hale magnetic field polarity
reversal first occured at the active longitudes. Thus, the stable
longitudinal structures play an important role in the mechanism of
the solar cycle. These structures are also revealed in the large-scale
structure of the corona. We study the relation between the magnetic and
coronal longitudinal structures, and their role in formation of coronal
holes. We discuss the relations between rotation of the longitudinal
structures in the photosphere and corona and compare with the rotation
rate of the solar interior using helioseismic data. This work was
carried out in the collaboration with J. T. Hoeksema, A. G. Kosovichev
and P. H. Scherrer of Stanford University.
Title: Solar Active Longitudes and Their Rotations Using SOHO-MDI Data
(CD-ROM Directory: contribs/benevo2)
Authors: Benevolenskaya, E. E.; Hoeksema, J. T.; Kosovichev, A. G.;
Scherrer, P. H.
Bibcode: 2001ASPC..223..583B
Altcode: 2001csss...11..583B
No abstract at ADS
Title: Helicity Variations on the Sun (CD-ROM Directory:
contribs/benevo1)
Authors: Benevolenskaya, E. E.
Bibcode: 2001ASPC..223..577B
Altcode: 2001csss...11..577B
No abstract at ADS
Title: Active Longitudes in Solar Corona
Authors: Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 2000SPD....31.0226B
Altcode: 2000BAAS...32..815B
We present the results of the investigation of the large-scale
structure of the solar corona during the transition period between
solar cycles 22 and 23 and at the beginning of the current cycle 23
using the SOHO/EIT EUV data obtained in 171 Angstroms, 195 Angstroms,
284 Angstroms and 304 Angstroms lines. For this analysis the data
were transformed into synoptic maps for each of the spectral lines,
and for the 195 Angstroms/171 Angstroms line ratio which is an
index of the coronal temperature. The synoptic maps reveal stable
longitudinal structures in the coronal intensities and temperature,
which are related to large-scale magnetic field structures. We discuss
the relation between the coronal and photospheric magnetic structures
obtained from the SOHO/MDI data, and compare the rotation rates of
these structures with the rotation profile of the solar interior in
order to determine the possible origin of the coronal structures.
Title: A mechanism of helicity variations on the Sun
Authors: Benevolenskaya, Elena E.
Bibcode: 2000SoPh..191..247B
Altcode:
Helicity of solar magnetic fields plays an important role in dynamo
theories of the solar cycle. The helicity has been known to vary with
the main 11-year period (Hale's cycle). Recent observations have
revealed significant helicity variations on a shorter time scale,
with a characteristic period of approximately 2 years. We suggest
an explanation for the observed variations of the magnetic helicity,
based on our model of the double magnetic cycle of solar activity. The
quasi-biennial variations of the helicity are the consequence of
the influence of erupted magnetic fields of the main cycle on the
helicity in the regions of generation of the high-frequency component
of magnetic field. This model suggests that the low-frequency component
is generated at the base of the convective zone due to large-scale
radial shear ∂Ω/∂r of angular velocity Ω. The high-frequency
component may be generated in the subsurface region due to latitudinal
shear ∂Ω/∂θ or due to the radial shear in this region.
Title: Variations of the Magnetic Helicity
Authors: Benevolenskaya, E. E.
Bibcode: 1999ESASP.448...31B
Altcode: 1999ESPM....9...31B; 1999mfsp.conf...31B
No abstract at ADS
Title: New and Old Magnetic Fluxes at the Beginning of Solar Cycle 23
Authors: Benevolenskaya, E. E.; Hoeksema, J. T.; Kosovichev, A. G.;
Scherrer, P. H.
Bibcode: 1999ESASP.448...69B
Altcode: 1999ESPM....9...69B; 1999mfsp.conf...69B
No abstract at ADS
Title: Structure and Dynamics of Interconnecting Loops and Coronal
Holes in Active Longitudes
Authors: Benevolenskaya, Elena E.; Kosovichev, A. G.; Scherrer, P. H.
Bibcode: 1999SoPh..190..145B
Altcode:
Using SOHO/MDI and SOHO/EIT data we study properties and dynamics
of interconnected active regions, and the relations between the
photospheric magnetic fields and coronal structures in active longitudes
during the beginning of solar cycle 23. The emergence of new magnetic
flux results in appearance of new interconnecting loops. The existence
of stable coronal structures strongly depends on the photospheric
magnetic fluxes and their variations. We present some initial results
for a complex of solar activity observed in April 1997, and discuss
the role of reconnection in the formation of the interconnected loops
and coronal holes.
Title: The Interaction of New and Old Magnetic Fluxes at the Beginning
of Solar Cycle 23
Authors: Benevolenskaya, E. E.; Hoeksema, J. T.; Kosovichev, A. G.;
Scherrer, P. H.
Bibcode: 1999ApJ...517L.163B
Altcode: 1999astro.ph..3404B
The 11 yr cycle of solar activity follows Hale's law by reversing
the magnetic polarity of leading and following sunspots in bipolar
regions during the minima of activity. In the 1996-1997 solar minimum,
most solar activity emerged in narrow longitudinal zones--``active
longitudes'' but over a range in latitude. Investigating the
distribution of solar magnetic flux, we have found that the Hale
sunspot polarity reversal first occurred in these active zones. We have
estimated the rotation rates of the magnetic flux in the active zones
before and after the polarity reversal. Comparing these rotation rates
with the internal rotation inferred by helioseismology, we suggest
that both ``old'' and ``new'' magnetic fluxes were probably generated
in a low-latitude zone near the base of the solar convection zone. The
reversal of active region polarity observed in certain longitudes at the
beginning of a new solar cycle suggests that the phenomenon of active
longitudes may give fundamental information about the mechanism of
the solar cycle. The nonrandom distribution of old-cycle and new-cycle
fluxes presents a challenge for dynamo theories, most of which assume
a uniform longitudinal distribution of solar magnetic fields.
Title: The Magnetic Structure of the Sun at the Beginning of Solar
Cycle 23
Authors: Benevolenskaya, E. E.; Hoeksema, J. T.; Kosovichev, A. G.;
Scherrer, P. H.
Bibcode: 1999AAS...194.9201B
Altcode: 1999BAAS...31R.986B
The 11-year cycle of solar activity follows Hale's law by reversing the
magnetic polarity of leading and following sunspots in bipolar regions
during the minima of activity. In the 1996-97 solar minimum, most solar
activity emerged in narrow longitudinal zones - `active longitudes'
but over a range in latitude. Investigating the distribution of solar
magnetic flux, we have found that the Hale sunspot polarity reversal
first occurred in these active zones. We have estimated the rotation
rates of the magnetic flux in the active zones before and after the
polarity reversal. Comparing these rotation rates with the internal
rotation inferred by helioseismology, we suggest that both `old' and
`new' magnetic fluxes were probably generated in a low-latitude zone
near the base of the solar convection zone. The reversal of active
region polarity observed in certain longitudes at the beginning of
a new solar cycle suggests that the phenomenon of active longitudes
may give fundamental information about the mechanism of the solar
cycle. The non-random distribution of old-cycle and new-cycle fluxes
presents a challenge for dynamo theories, most of which assume a
uniform longitudinal distribution of solar magnetic fields. We have
used accurate measurements of solar oscillation frequencies from the
GONG and SOHO/MDI to infer the latitudinal dependence of the solar
structure associated with magnetic fields beneath the surface. The
results show significant variations of the aspherical structure of
the Sun at the beginning of the new cycle. These variations correlate
with the latitudinal distribution of the surface magnetic flux. We
discuss possible variations at the base of the convection zone and
their relation to the dynamo mechanism.
Title: Longitudinal Structure of Solar Magnetic Fields During the
Transition from Cycle 22 to Cycle 23 Inferred from SOHO MDI Data
Authors: Benevolenskaya, Elena E.
Bibcode: 1999soho....9E..41B
Altcode:
We present the results of investigation the latitudinal and longitudinal
structure of the solar magnetic field by using full disk SOHO MDI
data. It was found that during the transition from cycle 22 to cycle
23 solar activity clustered in fixed longitudinal zones, and that the
old magnetic fluxes were replaced by new magnetic fluxes in the same
fixed longitudinal regions. The most interesting longitudinal zone
was located from 240 deg to 280 deg. From the CR1911 until CR1918,
there was a complex of activity of old magnetic fluxes. This complex
of solar activity first emerged in the southern hemisphere and
decayed to CR1916. Then, the next old magnetic flux appeared in the
same longitudinal zone in the northern hemisphere and existed until
CR1919. The same longitudinal zone became active again in CR1923
when a complex of solar activity of new magnetic flux emerged. This
longitudinal zone of pronounced activity existed for more than 15
Carrington rotations. Apparently, this zone was the place of reversal
of polarity of the toroidal magnetic field during the transition from
one cycle to another. We discuss implications of these results for
theories of solar cycle.
Title: A model of the double magnetic cycle.
Authors: Benevolenskaya, E. E.
Bibcode: 1999joso.proc..203B
Altcode:
The solar magnetic cycle consists of two cycles: low-frequency (Hale's
cycle) and high-frequency (quasi-biennial cycle). Using Stanford,
Mount Wilson and Kitt Peak magnetograph data from 1976 to 1996
(solar cycles 21 and 22) it has been found a double magnetic cycle
(Benevolenskaya 1995, 1996). In frame of the Parker's dynamo theory
a model of the double magnetic cycle was presented. There exist two
sources of the magnetic cycle separated by space. The first is located
at the lower level of the convection zone and a second operates in
subsurface regions. As a result two systems of non-linear equations
were constructed. In case of weak interaction between these systems
a double magnetic cycle was obtained.
Title: A Mechanism of Helicity Variations on the Sun
Authors: Benevolenskaya, E. E.
Bibcode: 1999soho....9E..42B
Altcode:
Helicity of solar magnetic fields plays an important role in dynamo
theories of the solar cycle. The helicity has been known to vary with
the main 11-year period (Hale's cycle). Recent observations have
revealed significant helicity variations on a shorter time scale,
with a characteristic period of approximately 2 years. We suggest
an explanation for the observed variations of the magnetic helicity,
based on our model of the double magnetic cycle of solar activity. The
quasi-biennial variations of the helicity are the consequence of
the influence of erupted magnetic fields of the main cycle on the
helicity in the regions of generation of the high-frequency component
of magnetic field. This model suggests that the low-frequency component
of is generated at the base of the convective zone due to large-scale
radial shear of angular velocity. The high-frequency component may be
generated in the subsurface region due to latitudinal shear or due to
the radial shear in this region.
Title: A Model of the Double Magnetic Cycle of the Sun
Authors: Benevolenskaya, E. E.
Bibcode: 1998ApJ...509L..49B
Altcode: 1998astro.ph.10329B
It has been argued that the solar magnetic cycle consists of two main
periodic components: a low-frequency component (Hale's 22 yr cycle)
and a high-frequency component (quasi-biennial cycle). The existence
of the double magnetic cycle on the Sun is confirmed using Stanford,
Mount Wilson, and Kitt Peak magnetograph data from 1976 to 1996 (solar
cycles 21 and 22). In the frame of the Parker's dynamo theory, a model
of the double magnetic cycle is presented. This model is based on the
idea of two dynamo sources separated in space. The first source of
the dynamo action is located near the bottom of the convection zone,
and the second operates near the top. The model is formulated in
terms of two coupled systems of nonlinear differential equations. It
is demonstrated that in the case of a weak interaction between the
two dynamo sources, the basic features of the double magnetic cycle,
such as the existence of two components and the observed temporal
variations of the high-frequency component, can be reproduced.
Title: Longitudinal Structure of the Double Magnetic Cycle
Authors: Benevolenskaya, Elena E.
Bibcode: 1998SoPh..181..479B
Altcode:
The longitudinal structure of the double magnetic cycle of solar
activity has been investigated using Stanford magnetograph data from
1976 to 1996 (cycles 21 and 22). It is shown that both high-frequency
and low-frequency sources of the magnetic field are present in the
data and that they reach their maxima in longitudinal zones that are
separated by 20°. Some longitudinal zones are found to exist in which
the high-frequency component is dominant and other longitudinal zones
are found in which the low-frequency component is dominant.
Title: Solar Magnetic Cycle Inferred from Synoptic Observations
Authors: Benevolenskaya, Elena E.
Bibcode: 1998ASPC..140...57B
Altcode: 1998ssp..conf...57B
No abstract at ADS
Title: Distribution of the sources of the magnetic field during the
double magnetic cycle
Authors: Benevolenskaya, Elena E.
Bibcode: 1998IAUS..185..463B
Altcode:
There exist the sources of the double magnetic cycle: low-frequency
component (Hale cycle) and high-frequency component (biennial cycle). It
seems that an interaction between these components in the convection
zone takes place on the Sun. Surface large-scale solar magnetic fields
are analyzed using a two-dimensional Fourier method technique, to study
the poloidal field distribution using Stanford magnetograph data from
1976 to 1996 (Solar Cycles 21 and 22). The first harmonic approximately
equals the period of the magnetic cycle, appears at all latitudes,
and reaches its the maximum value in the polar regions. Spectral
analyzes of axisymmetrical magnetic field derivative in time found
that the second important harmonic of a period approximately equal
of two years appears at all latitudes. This second high-frequency
harmonic dominates the polar latitude regions at the same time as
low-frequency one. Moreover the longitudinal structure of the double
magnetic cycle has been investigated . It is shown that high-frequency
and low-frequency sources of the magnetic field turn out to reach
their maxima in longitudinal zones separated by 20^o. There exist some
longitudinal zones in which high-frequency component are dominant and
other longitudinal zones with a pronounced low-frequency component.
Title: Origin of the Polar Magnetic Field Reversals
Authors: Benevolenskaya, E. E.
Bibcode: 1996SoPh..167...47B
Altcode:
The polar magnetic field on the Sun changes its sign during the maximum
of solar cycles. It is known that the phenomenon of three-fold reversal
of the polar magnetic field occurred in solar cycle 20. Using the
magnetograph data of the Mount Wilson Observatory from 1967 to 1993,
we confirm a previously suggested topological model of the three-fold
magnetic-field reversal (Benevolenskaya, 1991). From the data set we
have found that cycles with three-fold polar magnetic field reversals
are characterized by a pronounced high-frequency component of the
magnetic field compared with cycles with single polar magnetic-field
reversals.
Title: Double Magnetic Cycle of Solar Activity
Authors: Benevolenskaya, E. E.
Bibcode: 1995SoPh..161....1B
Altcode:
The source of the poloidal magnetic field was fixed using a uniform
series of surface low-resolution magnetic field observations begun
at Wilcox Solar Observatory at Stanford. The results obtained confirm
the idea that low-frequency dynamo waves with a period approximately
equal to 22 years and a high-frequency wave of a quasi-two-year period
can coexist. It seems that an interaction between these components
in the convection zone takes place on the Sun. Surface large-scale
solar magnetic fields are analyzed using a two-dimensional Fourier
method technique to study the poloidal field distribution. The first
harmonic approximately equals the period of the magnetic cycle,
appears at all latitudes, and reaches its the maximum value in the
polar regions. Moreover, spectral analyses of axisymmetric magnetic
field derivative in time found that the second important harmonic of a
period approximately equal to two years appears at all latitudes. This
second high-frequency harmonic dominates the polar latitude regions
at the same time as the low-frequency one.
Title: Structure of the solar magnetic cycle: Spectral composition
Authors: Benevolenskaya, E. E.
Bibcode: 1995AstL...21..495B
Altcode: 1995PAZh...21..557B
No abstract at ADS
Title: The structure of the solar magnetic cycle
Authors: Benevolenskaya, E. E.
Bibcode: 1994AstL...20..468B
Altcode: 1994PAZh...20..551B
No abstract at ADS
Title: The solar dynamo and the surface magnetic field of the Sun
Authors: Benevolenskaya, E. E.
Bibcode: 1994smf..conf..113B
Altcode:
No abstract at ADS
Title: Sign reversal of the high-latitude solar magnetic field
Authors: Benevolenskaja, E. E.; Makarov, V. I.
Bibcode: 1992SvAL...18..108B
Altcode: 1992PAZh...18..266B
It is assumed that the existence of threefold magnetic field
reversals in one of the solar hemispheres is the result of two types
of variations in the background magnetic field. The first type is the
Hale 22-yr cycle; the second is a quasi-biannual cycle. In the first
approximation, the background magnetic field evolution can be described
by a diffusion equation corrected for meridional circulation and with
a periodically changing source. Numerical modeling shows that, in the
case of multiplicity of the frequencies and under a certain relationship
between the amplitudes of these periods, zones of polarity reversals
may form during maxima of even 11-yr (Zurich numbering) cycles.
Title: The Solar High Latitude Magnetic Field Reversal
Authors: Benevolenskaya, Elena E.; Makarov, V. I.
Bibcode: 1992ASPC...27..532B
Altcode: 1992socy.work..532B
No abstract at ADS
Title: Quasi-biennial variation and latitude solar magnetic field
reversal.
Authors: Benevolenskaya, E. E.; Makarov, V. I.
Bibcode: 1991BSolD...2...89B
Altcode:
No abstract at ADS
Title: A Topological Model of the Solar Magnetic Field Reversals
Authors: Benevolenskaya, E. E.
Bibcode: 1991LNP...380..234B
Altcode: 1991IAUCo.130..234B; 1991sacs.coll..234B
No abstract at ADS
Title: A topological model of the sun's threefold magnetic field
reversals.
Authors: Benevolenskaya, E. E.; Makarov, V. I.
Bibcode: 1990BSolD...5...75B
Altcode:
It is shown that single and threefold reversals of the solar magnetic
field may be a result from interaction of two types of magnetic
fields: of a low-frequency field of the order of 22 years and of a
high-frequency field of the order of 1.5 years.
Title: The primary magnetic field of the sun and solar activity.
Authors: Pudovkin, M. I.; Benevolenskaia, E. E.
Bibcode: 1986MagIs...6...23P
Altcode:
The existence of prolonged epochs of reduced solar activity (e.g.,
the Maunder minimum) is explained in the framework of Leighton's (1969)
model, taking into account the slowly varying primordial magnetic field
of the sun. The relationship between background magnetic fields and
the intensity of 11-year cycles is established, opening the possibility
of predicting solar-cycle maxima.
Title: Modeling of the 22-YEAR Solar Activity Cycle Within the
Framework of the Dynamo Theory with Allowance for the Primary Field
Authors: Pudovkin, M. I.; Benevolenskaya, E. E.
Bibcode: 1984SvA....28..458P
Altcode:
No abstract at ADS
Title: Modeling of the 22-year solar activity cycle within the
framework of the dynamo theory with allowance for the primary field
Authors: Pudovkin, M. I.; Benevolenskaya, E. E.
Bibcode: 1984AZh....61..783P
Altcode:
The influence of a hypothetical, quasi-steady primary field of the
sun on the behavior of solar activity and the background magnetic
field during the 22-year solar cycle is considered. It is shown that
allowance for the primary solar field in Leighton's model makes it
possible to explain the main regularities of behavior of the surface
magnetic field of the sun and the solar activity during the 22-year
cycle. These regularities are confirmed by a direct comparison with
experimental results. The possibility in principle of experimentally
detecting the internal field of the sun and estimating its parameters
from its manifestations in the surface layers is thereby demonstrated.
Title: Quasi-stationary primary magnetic field of the sun and
intensity variations of the solar cycle.
Authors: Benevolenskaya, E. E.; Pudovkin, M. I.
Bibcode: 1982PAZh....8..506B
Altcode:
No abstract at ADS
Title: The quasisteady primordial magnetic field of the sun, and
the intensity variations of the solar cycle
Authors: Pudovkin, M. I.; Benevolenskaia, E. E.
Bibcode: 1982PAZh....8..506P
Altcode:
The behavior of the solar activity cycle is analyzed on the basis of
Leighton's model, assuming the presence of a primordial, nondecaying
poloidal magnetic field. The primordial field would significantly
influence the cyclicity, causing relatively intense cycles to alternate
with less intense ones.
Title: The Quasisteady Primordial Magnetic Field of the Sun and the
Intensity Variations of the Solar Cycle
Authors: Pudovkin, M. I.; Benevolenskaya, E. E.
Bibcode: 1982SvAL....8..273P
Altcode:
No abstract at ADS
Title: On the Problem of Prediction of the Maxima of Solar Activity
Using Polar Fields on the Sun
Authors: Benevolenskaya, E. E.
Bibcode: 1982BSolD...3..108B
Altcode:
No abstract at ADS
Title: On the problem of prediction of the maxima of solar activity
using polar fields on the sun.
Authors: Benevolenskaya, E. E.
Bibcode: 1982BSolD1982..108B
Altcode:
No abstract at ADS