Author name code: straus ADS astronomy entries on 2022-09-14 author:"Straus, Thomas" ------------------------------------------------------------------------ Title: Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations Authors: Telloni, Daniele; Zank, Gary P.; Sorriso-Valvo, Luca; D'Amicis, Raffaella; Panasenco, Olga; Susino, Roberto; Bruno, Roberto; Perrone, Denise; Adhikari, Laxman; Liang, Haoming; Nakanotani, Masaru; Zhao, Lingling; Hadid, Lina Z.; Sánchez-Cano, Beatriz; Verscharen, Daniel; Velli, Marco; Grimani, Catia; Marino, Raffaele; Carbone, Francesco; Mancuso, Salvatore; Biondo, Ruggero; Pagano, Paolo; Reale, Fabio; Bale, Stuart D.; Kasper, Justin C.; Case, Anthony W.; de Wit, Thierry Dudok; Goetz, Keith; Harvey, Peter R.; Korreck, Kelly E.; Larson, Davin; Livi, Roberto; MacDowall, Robert J.; Malaspina, David M.; Pulupa, Marc; Stevens, Michael L.; Whittlesey, Phyllis; Romoli, Marco; Andretta, Vincenzo; Deppo, Vania Da; Fineschi, Silvano; Heinzel, Petr; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Stangalini, Marco; Teriaca, Luca; Capobianco, Gerardo; Capuano, Giuseppe E.; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso, Alain J.; Leo, Yara De; Fabi, Michele; Frassati, Federica; Frassetto, Fabio; Giordano, Silvio; Guglielmino, Salvo L.; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli, Enrico; Massone, Giuseppe; Messerotti, Mauro; Pancrazzi, Maurizio; Pelizzo, Maria G.; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Slemer, Alessandra; Straus, Thomas; Uslenghi, Michela; Volpicelli, Cosimo A.; Zangrilli, Luca; Zuppella, Paola; Abbo, Lucia; Auchère, Frédéric; Cuadrado, Regina Aznar; Berlicki, Arkadiusz; Ciaravella, Angela; Lamy, Philippe; Lanzafame, Alessandro; Malvezzi, Marco; Nicolosi, Piergiorgio; Nisticò, Giuseppe; Peter, Hardi; Solanki, Sami K.; Strachan, Leonard; Tsinganos, Kanaris; Ventura, Rita; Vial, Jean-Claude; Woch, Joachim; Zimbardo, Gaetano Bibcode: 2022ApJ...935..112T Altcode: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R ⊙ above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvénic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin. Title: Cosmic-ray flux predictions and observations for and with Metis on board Solar Orbiter Authors: Grimani, C.; Andretta, V.; Chioetto, P.; Da Deppo, V.; Fabi, M.; Gissot, S.; Naletto, G.; Persici, A.; Plainaki, C.; Romoli, M.; Sabbatini, F.; Spadaro, D.; Stangalini, M.; Telloni, D.; Uslenghi, M.; Antonucci, E.; Bemporad, A.; Capobianco, G.; Capuano, G.; Casti, M.; De Leo, Y.; Fineschi, S.; Frassati, F.; Frassetto, F.; Heinzel, P.; Jerse, G.; Landini, F.; Liberatore, A.; Magli, E.; Messerotti, M.; Moses, D.; Nicolini, G.; Pancrazzi, M.; Pelizzo, M. G.; Romano, P.; Sasso, C.; Schühle, U.; Slemer, A.; Straus, T.; Susino, R.; Teriaca, L.; Volpicelli, C. A.; Freiherr von Forstner, J. L.; Zuppella, P. Bibcode: 2021A&A...656A..15G Altcode: 2021arXiv210413700G Context. The Metis coronagraph is one of the remote sensing instruments hosted on board the ESA/NASA Solar Orbiter mission. Metis is devoted to carry out the first simultaneous imaging of the solar corona in both visible light (VL) and ultraviolet (UV). High-energy particles can penetrate spacecraft materials and may limit the performance of the on-board instruments. A study of the galactic cosmic-ray (GCR) tracks observed in the first VL images gathered by Metis during the commissioning phase is presented here. A similar analysis is planned for the UV channel.
Aims: We aim to formulate a prediction of the GCR flux up to hundreds of GeV for the first part of the Solar Orbiter mission to study the performance of the Metis coronagraph.
Methods: The GCR model predictions are compared to observations gathered on board Solar Orbiter by the High-Energy Telescope in the range between 10 MeV and 100 MeV in the summer of 2020 as well as with the previous measurements. Estimated cosmic-ray fluxes above 70 MeV n−1 have been also parameterized and used for Monte Carlo simulations aimed at reproducing the cosmic-ray track observations in the Metis coronagraph VL images. The same parameterizations can also be used to study the performance of other detectors.
Results: By comparing observations of cosmic-ray tracks in the Metis VL images with FLUKA Monte Carlo simulations of cosmic-ray interactions in the VL detector, we find that cosmic rays fire only a fraction, on the order of 10−4, of the whole image pixel sample. We also find that the overall efficiency for cosmic-ray identification in the Metis VL images is approximately equal to the contribution of Z ≥ 2 GCR particles. A similar study will be carried out during the whole of the Solar Orbiter's mission duration for the purposes of instrument diagnostics and to verify whether the Metis data and Monte Carlo simulations would allow for a long-term monitoring of the GCR proton flux. Title: First light observations of the solar wind in the outer corona with the Metis coronagraph Authors: Romoli, M.; Antonucci, E.; Andretta, V.; Capuano, G. E.; Da Deppo, V.; De Leo, Y.; Downs, C.; Fineschi, S.; Heinzel, P.; Landini, F.; Liberatore, A.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Sasso, C.; Spadaro, D.; Susino, R.; Telloni, D.; Teriaca, L.; Uslenghi, M.; Wang, Y. -M.; Bemporad, A.; Capobianco, G.; Casti, M.; Fabi, M.; Frassati, F.; Frassetto, F.; Giordano, S.; Grimani, C.; Jerse, G.; Magli, E.; Massone, G.; Messerotti, M.; Moses, D.; Pelizzo, M. -G.; Romano, P.; Schühle, U.; Slemer, A.; Stangalini, M.; Straus, T.; Volpicelli, C. A.; Zangrilli, L.; Zuppella, P.; Abbo, L.; Auchère, F.; Aznar Cuadrado, R.; Berlicki, A.; Bruno, R.; Ciaravella, A.; D'Amicis, R.; Lamy, P.; Lanzafame, A.; Malvezzi, A. M.; Nicolosi, P.; Nisticò, G.; Peter, H.; Plainaki, C.; Poletto, L.; Reale, F.; Solanki, S. K.; Strachan, L.; Tondello, G.; Tsinganos, K.; Velli, M.; Ventura, R.; Vial, J. -C.; Woch, J.; Zimbardo, G. Bibcode: 2021A&A...656A..32R Altcode: 2021arXiv210613344R In this work, we present an investigation of the wind in the solar corona that has been initiated by observations of the resonantly scattered ultraviolet emission of the coronal plasma obtained with UVCS-SOHO, designed to measure the wind outflow speed by applying Doppler dimming diagnostics. Metis on Solar Orbiter complements the UVCS spectroscopic observations that were performed during solar activity cycle 23 by simultaneously imaging the polarized visible light and the H I Lyman-α corona in order to obtain high spatial and temporal resolution maps of the outward velocity of the continuously expanding solar atmosphere. The Metis observations, taken on May 15, 2020, provide the first H I Lyman-α images of the extended corona and the first instantaneous map of the speed of the coronal plasma outflows during the minimum of solar activity and allow us to identify the layer where the slow wind flow is observed. The polarized visible light (580-640 nm) and the ultraviolet H I Lyα (121.6 nm) coronal emissions, obtained with the two Metis channels, were combined in order to measure the dimming of the UV emission relative to a static corona. This effect is caused by the outward motion of the coronal plasma along the direction of incidence of the chromospheric photons on the coronal neutral hydrogen. The plasma outflow velocity was then derived as a function of the measured Doppler dimming. The static corona UV emission was simulated on the basis of the plasma electron density inferred from the polarized visible light. This study leads to the identification, in the velocity maps of the solar corona, of the high-density layer about ±10° wide, centered on the extension of a quiet equatorial streamer present at the east limb - the coronal origin of the heliospheric current sheet - where the slowest wind flows at about 160 ± 18 km s−1 from 4 R⊙ to 6 R⊙. Beyond the boundaries of the high-density layer, the wind velocity rapidly increases, marking the transition between slow and fast wind in the corona. Title: Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter-Parker Solar Probe Quadrature Authors: Telloni, Daniele; Andretta, Vincenzo; Antonucci, Ester; Bemporad, Alessandro; Capuano, Giuseppe E.; Fineschi, Silvano; Giordano, Silvio; Habbal, Shadia; Perrone, Denise; Pinto, Rui F.; Sorriso-Valvo, Luca; Spadaro, Daniele; Susino, Roberto; Woodham, Lloyd D.; Zank, Gary P.; Romoli, Marco; Bale, Stuart D.; Kasper, Justin C.; Auchère, Frédéric; Bruno, Roberto; Capobianco, Gerardo; Case, Anthony W.; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso, Alain J.; Da Deppo, Vania; De Leo, Yara; Dudok de Wit, Thierry; Frassati, Federica; Frassetto, Fabio; Goetz, Keith; Guglielmino, Salvo L.; Harvey, Peter R.; Heinzel, Petr; Jerse, Giovanna; Korreck, Kelly E.; Landini, Federico; Larson, Davin; Liberatore, Alessandro; Livi, Roberto; MacDowall, Robert J.; Magli, Enrico; Malaspina, David M.; Massone, Giuseppe; Messerotti, Mauro; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo; Nisticò, Giuseppe; Panasenco, Olga; Pancrazzi, Maurizio; Pelizzo, Maria G.; Pulupa, Marc; Reale, Fabio; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Stangalini, Marco; Stevens, Michael L.; Strachan, Leonard; Straus, Thomas; Teriaca, Luca; Uslenghi, Michela; Velli, Marco; Verscharen, Daniel; Volpicelli, Cosimo A.; Whittlesey, Phyllis; Zangrilli, Luca; Zimbardo, Gaetano; Zuppella, Paola Bibcode: 2021ApJ...920L..14T Altcode: 2021arXiv211011031T This Letter addresses the first Solar Orbiter (SO)-Parker Solar Probe (PSP) quadrature, occurring on 2021 January 18 to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in the corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfvén radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfvénic solar corona to just above the Alfvén surface. Title: In-flight optical performance assessment for the Metis solar coronagraph Authors: Da Deppo, Vania; Chioetto, Paolo; Andretta, Vincenzo; Casini, Chiara; Frassetto, Fabio; Slemer, Alessandra; Zuppella, Paola; Romoli, Marco; Fineschi, Silvano; Heinzel, Petr; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Stangalini, Marco; Teriaca, Luca; Bemporad, Alessandro; Casti, Marta; Fabi, Michele; Grimani, Catia; Heerlein, Klaus; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli, Enrico; Melich, Radek; Pancrazzi, Maurizio; Pelizzo, Maria-G.; Romano, Paolo; Sasso, Clementina; Straus, Thomas; Susino, Roberto; Uslenghi, Michela; Volpicelli, Cosimo Antonio Bibcode: 2021SPIE11852E..10D Altcode: Metis is a multi-wavelength coronagraph onboard the European Space Agency (ESA) Solar Orbiter mission. The instrument features an innovative instrument design conceived for simultaneously imaging the Sun's corona in the visible and ultraviolet range. The Metis visible channel employs broad-band, polarized imaging of the visible K-corona, while the UV one uses narrow-band imaging at the HI Ly 􀄮, i.e. 121.6 nm. During the commissioning different acquisitions and activities, performed with both the Metis channels, have been carried out with the aim to check the functioning and the performance of the instrument. In particular, specific observations of stars have been devised to assess the optical alignment of the telescope and to derive the instrument optical parameters such as focal length, PSF and possibly check the optical distortion and the vignetting function. In this paper, the preliminary results obtained for the PSF of both channels and the determination of the scale for the visible channel will be described and discussed. The in-flight obtained data will be compared to those obtained on-ground during the calibration campaign. Title: On-ground flat-field calibration of the Metis coronagraph onboard the Solar Orbiter ESA mission Authors: Casini, C.; Da Deppo, V.; Zuppella, P.; Chioetto, P.; Slemer, A.; Frassetto, F.; Romoli, M.; Landini, F.; Pancrazzi, M.; Andretta, V.; De Leo, Y.; Bemporad, A.; Fabi, M.; Fineschi, S.; Frassati, F.; Grimani, C.; Jerse, G.; Heerlein, K.; Liberatore, A.; Magli, E.; Naletto, G.; Nicolini, G.; Pelizzo, M. G.; Romano, P.; Sasso, C.; Spadaro, D.; Stangalini, M.; Straus, T.; Susino, R.; Teriaca, L.; Uslenghi, M.; Casti, M.; Heinzel, P.; Volpicelli, A. Bibcode: 2021SPIE11852E..5BC Altcode: Solar Orbiter, launched on February 9th 2020, is an ESA/NASA mission conceived to study the Sun. This work presents the embedded Metis coronagraph and its on-ground calibration in the 580-640 nm wavelength range using a flat field panel. It provides a uniform illumination to evaluate the response of each pixel of the detector; and to characterize the Field of View (FoV) of the coronagraph. Different images with different exposure times were acquired during the on-ground calibration campaign. They were analyzed to verify the linearity response of the instrument and the requirements for the FoV: the maximum area of the sky that Metis can acquire. Title: Challenges during Metis-Solar Orbiter commissioning phase Authors: Romoli, Marco; Andretta, Vincenzo; Bemporad, Alessandro; Casti, Marta; Da Deppo, Vania; De Leo, Yara; Fabi, Michele; Fineschi, Silvano; Frassetto, Fabio; Grimani, Catia; Heerlein, Klaus; Heinzel, Petr; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli, Enrico; Naletto, Giampiero; Nicolini, Gianalfredo; Pancrazzi, Maurizio; Pelizzo, Maria Guglielmina; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Slemer, Alessandra; Spadaro, Daniele; Straus, Thomas; Susino, Roberto; Teriaca, Luca; Uslenghi, Michela; Volpicelli, Cosimo Antonio; Zupella, Paola Bibcode: 2021SPIE11852E..5AR Altcode: Metis is the visible light and UV light imaging coronagraph on board the ESA-NASA mission Solar Orbiter that has been launched February 10th, 2020, from Cape Canaveral. Scope of the mission is to study the Sun up close, taking high-resolution images of the Sun's poles for the first time, and understanding the Sun-Earth connection. Metis coronagraph will image the solar corona in the linearly polarized broadband visible radiation and in the UV HI Ly-α line from 1.6 to 3 solar radii when at Solar Orbiter perihelion, providing a diagnostics, with unprecedented temporal coverage and spatial resolution, of the structures and dynamics of the full corona. Solar Orbiter commissioning phase big challenge was Covid-19 social distancing phase that affected the way commissioning of a spacecraft and its payload is typically done. Metis coronagraph on-board Solar Orbiter had its additional challenges: to wake up and check the performance of the optical, electrical and thermal subsystems, most of them unchecked since Metis delivery to spacecraft prime, Airbus, in May 2017. The roadmap to the fully commissioned coronagraph is here described throughout the steps from the software functional test, the switch on of the detectors of the two channels, UV and visible, to the optimization of the occulting system and the characterization of the instrumental stray light, one of the most challenging features in a coronagraph. Title: In-flight calibration of Metis coronagraph on board of Solar Orbiter Authors: Liberatore, A.; Fineschi, S.; Casti, M.; Capobianco, G.; Romoli, M.; Andretta, V.; Bemporad, A.; Da Deppo, V.; De Leo, Y.; Fabi, M.; Frassetto, F.; Grimani, C.; Heerlein, K.; Heinzel, P.; Jerse, G.; Landini, F.; Magli, E.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Pelizzo, M. G.; Romano, P.; Sasso, C.; Slemer, A.; Spadaro, D.; Straus, T.; Susino, R.; Teriaca, L.; Uslenghi, M.; Volpicelli, C. A.; Zuppella, P. Bibcode: 2021SPIE11852E..48L Altcode: Metis coronagraph is one of the remote-sensing instruments of the Solar Orbiter mission launched at the begin of 2020. The mission profile will allow for the first time the remote-sensing observation of the Sun from a very close distance and increasing the latitude with respect to the ecliptic plane. In particular, Metis is aimed at the overall characterization and study of the solar corona and solar wind. Metis instrument acquires images of the solar corona in two different wavelengths simultaneously; ultraviolet (UV) and visible-light (VL). The VL channel includes a polarimeter with an electro-optically modulating Liquid Crystal Variable Retarder (LCVR) to measure the linearly polarized brighness pB) of the K-corona. This paper presents part of the in-flight calibration results for both wavelength channels together with a comparison with on-ground calibrations. The orientation of the K-corona linear polarization was used for the in-flight calibration of the Metis polarimeter. This paper describes the correction of the on-ground VL vignetting function after the in-flight adjustment of the internal occulter. The same vignetting function was adaptated to the UV channel. Title: The signature of granulation in a solar power spectrum as seen with CO5BOLD Authors: Lundkvist, Mia S.; Ludwig, Hans-Günter; Collet, Remo; Straus, Thomas Bibcode: 2021MNRAS.501.2512L Altcode: 2020arXiv201110045L; 2020MNRAS.tmp.3425L The granulation background seen in the power spectrum of a solar-like oscillator poses a serious challenge for extracting precise and detailed information about the stellar oscillations. Using a 3D hydrodynamical simulation of the Sun computed with CO5BOLD, we investigate various background models to infer, using a Bayesian methodology, which one provides the best fit to the background in the simulated power spectrum. We find that the best fit is provided by an expression including the overall power level and two characteristic frequencies, one with an exponent of two and one with a free exponent taking on a value around six. We assess the impact of the 3D hydro-code on this result by repeating the analysis with a simulation from S TAGGER and find that the main conclusion is unchanged. However, the details of the resulting best fits differ slightly between the two codes, but we explain this difference by studying the effect of the spatial resolution and the duration of the simulation on the fit. Additionally, we look into the impact of adding white noise to the simulated time series as a simple way to mimic a real star. We find that, as long as the noise level is not too low, the results are consistent with the no-noise case. Title: The MDOR/PDOR on-line module for MISO, the planning software of Solar Orbiter instruments Authors: Volpicelli, Cosimo; Landini, Federico; Pancrazzi, Maurizio; Straus, Thomas; Susino, Roberto; Nicolini, Gianalfredo; Sasso, Clementina; Fabi, Michele; De Leo, Yara; Casini, Chiara; Naletto, Giampiero; Nicolosi, Piergiorgio; Spadaro, Daniele; Andretta, Vincenzo; Antonucci, Ester; Fineschi, Silvano; Da Deppo, Vania; Zuppella, Paola; Frassetto, Fabio; Slemer, Alessandra; Mercier, Claude; Kouliche, Dimitri; Caminade, Stephane; Picard, David; Buchlin, Eric; Auchère, Frédéric; Romoli, Marco Bibcode: 2020SPIE11452E..0SV Altcode: Solar Orbiter is a solar mission that will approach the Sun down to a minimum perihelion of 0.28 AU and will increase its orbit inclination with respect to the ecliptic up to a maximum angle of 34 deg. For imagers aboard Solar Orbiter there will be three 10-days remote sensing windows per orbit. Observations shall be carefully planned at least 6 months in advance. The Multi Instrument Sequence Organizer (MISO) is a web based platform developed by the SPICE group and made available to support Solar Orbiter instruments teams in planning observations by assembling Mission Database sequences. Metis is the UV and visible light coronagraph aboard Solar Orbiter. Metis is a complex instrument characterized by a rich variety of observing modes, which required a careful commissioning activity and will need support for potential maintenance operations throughout the mission. In order to support commissioning and maintenance activities, the Metis team developed a PDOR (Payload Direct Operation Request) and MDOR (Memory Direct Operation Request) module integrated in MISO and made available to all Solar Orbiter instruments. An effort was made in order to interpret the coding philosophy of the main project and to make the additional module as homogeneous as possible both to the web interface and to the algorithm logic, while integrating characteristics which are peculiar to PDORs and MDORs. An user friendly web based interface allows the operator to build the operation request and to successively modify or integrate it with further or alternative information. In the present work we describe the PDOR/MDOR module for MISO by addressing its logic and main characteristics. Title: Coordination within the remote sensing payload on the Solar Orbiter mission Authors: Auchère, F.; Andretta, V.; Antonucci, E.; Bach, N.; Battaglia, M.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Caminade, S.; Carlsson, M.; Carlyle, J.; Cerullo, J. J.; Chamberlin, P. C.; Colaninno, R. C.; Davila, J. M.; De Groof, A.; Etesi, L.; Fahmy, S.; Fineschi, S.; Fludra, A.; Gilbert, H. R.; Giunta, A.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.; Howard, R. A.; Hurford, G.; Kleint, L.; Kolleck, M.; Krucker, S.; Lagg, A.; Landini, F.; Long, D. M.; Lefort, J.; Lodiot, S.; Mampaey, B.; Maloney, S.; Marliani, F.; Martinez-Pillet, V.; McMullin, D. R.; Müller, D.; Nicolini, G.; Orozco Suarez, D.; Pacros, A.; Pancrazzi, M.; Parenti, S.; Peter, H.; Philippon, A.; Plunkett, S.; Rich, N.; Rochus, P.; Rouillard, A.; Romoli, M.; Sanchez, L.; Schühle, U.; Sidher, S.; Solanki, S. K.; Spadaro, D.; St Cyr, O. C.; Straus, T.; Tanco, I.; Teriaca, L.; Thompson, W. T.; del Toro Iniesta, J. C.; Verbeeck, C.; Vourlidas, A.; Watson, C.; Wiegelmann, T.; Williams, D.; Woch, J.; Zhukov, A. N.; Zouganelis, I. Bibcode: 2020A&A...642A...6A Altcode: Context. To meet the scientific objectives of the mission, the Solar Orbiter spacecraft carries a suite of in-situ (IS) and remote sensing (RS) instruments designed for joint operations with inter-instrument communication capabilities. Indeed, previous missions have shown that the Sun (imaged by the RS instruments) and the heliosphere (mainly sampled by the IS instruments) should be considered as an integrated system rather than separate entities. Many of the advances expected from Solar Orbiter rely on this synergistic approach between IS and RS measurements.
Aims: Many aspects of hardware development, integration, testing, and operations are common to two or more RS instruments. In this paper, we describe the coordination effort initiated from the early mission phases by the Remote Sensing Working Group. We review the scientific goals and challenges, and give an overview of the technical solutions devised to successfully operate these instruments together.
Methods: A major constraint for the RS instruments is the limited telemetry (TM) bandwidth of the Solar Orbiter deep-space mission compared to missions in Earth orbit. Hence, many of the strategies developed to maximise the scientific return from these instruments revolve around the optimisation of TM usage, relying for example on onboard autonomy for data processing, compression, and selection for downlink. The planning process itself has been optimised to alleviate the dynamic nature of the targets, and an inter-instrument communication scheme has been implemented which can be used to autonomously alter the observing modes. We also outline the plans for in-flight cross-calibration, which will be essential to the joint data reduction and analysis.
Results: The RS instrument package on Solar Orbiter will carry out comprehensive measurements from the solar interior to the inner heliosphere. Thanks to the close coordination between the instrument teams and the European Space Agency, several challenges specific to the RS suite were identified and addressed in a timely manner. Title: Models and data analysis tools for the Solar Orbiter mission Authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.; Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.; Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.; Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi, N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla, T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.; Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.; Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.; Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.; Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot, V.; Georgoulis, M. K.; Gilbert, H. R.; Giunta, A.; Gomez-Herrero, R.; Guest, S.; Haberreiter, M.; Hassler, D.; Henney, C. J.; Howard, R. A.; Horbury, T. S.; Janvier, M.; Jones, S. I.; Kozarev, K.; Kraaikamp, E.; Kouloumvakos, A.; Krucker, S.; Lagg, A.; Linker, J.; Lavraud, B.; Louarn, P.; Maksimovic, M.; Maloney, S.; Mann, G.; Masson, A.; Müller, D.; Önel, H.; Osuna, P.; Orozco Suarez, D.; Owen, C. J.; Papaioannou, A.; Pérez-Suárez, D.; Rodriguez-Pacheco, J.; Parenti, S.; Pariat, E.; Peter, H.; Plunkett, S.; Pomoell, J.; Raines, J. M.; Riethmüller, T. L.; Rich, N.; Rodriguez, L.; Romoli, M.; Sanchez, L.; Solanki, S. K.; St Cyr, O. C.; Straus, T.; Susino, R.; Teriaca, L.; del Toro Iniesta, J. C.; Ventura, R.; Verbeeck, C.; Vilmer, N.; Warmuth, A.; Walsh, A. P.; Watson, C.; Williams, D.; Wu, Y.; Zhukov, A. N. Bibcode: 2020A&A...642A...2R Altcode: Context. The Solar Orbiter spacecraft will be equipped with a wide range of remote-sensing (RS) and in situ (IS) instruments to record novel and unprecedented measurements of the solar atmosphere and the inner heliosphere. To take full advantage of these new datasets, tools and techniques must be developed to ease multi-instrument and multi-spacecraft studies. In particular the currently inaccessible low solar corona below two solar radii can only be observed remotely. Furthermore techniques must be used to retrieve coronal plasma properties in time and in three dimensional (3D) space. Solar Orbiter will run complex observation campaigns that provide interesting opportunities to maximise the likelihood of linking IS data to their source region near the Sun. Several RS instruments can be directed to specific targets situated on the solar disk just days before data acquisition. To compare IS and RS, data we must improve our understanding of how heliospheric probes magnetically connect to the solar disk.
Aims: The aim of the present paper is to briefly review how the current modelling of the Sun and its atmosphere can support Solar Orbiter science. We describe the results of a community-led effort by European Space Agency's Modelling and Data Analysis Working Group (MADAWG) to develop different models, tools, and techniques deemed necessary to test different theories for the physical processes that may occur in the solar plasma. The focus here is on the large scales and little is described with regards to kinetic processes. To exploit future IS and RS data fully, many techniques have been adapted to model the evolving 3D solar magneto-plasma from the solar interior to the solar wind. A particular focus in the paper is placed on techniques that can estimate how Solar Orbiter will connect magnetically through the complex coronal magnetic fields to various photospheric and coronal features in support of spacecraft operations and future scientific studies.
Methods: Recent missions such as STEREO, provided great opportunities for RS, IS, and multi-spacecraft studies. We summarise the achievements and highlight the challenges faced during these investigations, many of which motivated the Solar Orbiter mission. We present the new tools and techniques developed by the MADAWG to support the science operations and the analysis of the data from the many instruments on Solar Orbiter.
Results: This article reviews current modelling and tool developments that ease the comparison of model results with RS and IS data made available by current and upcoming missions. It also describes the modelling strategy to support the science operations and subsequent exploitation of Solar Orbiter data in order to maximise the scientific output of the mission.
Conclusions: The on-going community effort presented in this paper has provided new models and tools necessary to support mission operations as well as the science exploitation of the Solar Orbiter data. The tools and techniques will no doubt evolve significantly as we refine our procedure and methodology during the first year of operations of this highly promising mission. Title: Metis: the Solar Orbiter visible light and ultraviolet coronal imager Authors: Antonucci, Ester; Romoli, Marco; Andretta, Vincenzo; Fineschi, Silvano; Heinzel, Petr; Moses, J. Daniel; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Berlicki, Arkadiusz; Capobianco, Gerardo; Crescenzio, Giuseppe; Da Deppo, Vania; Focardi, Mauro; Frassetto, Fabio; Heerlein, Klaus; Landini, Federico; Magli, Enrico; Marco Malvezzi, Andrea; Massone, Giuseppe; Melich, Radek; Nicolosi, Piergiorgio; Noci, Giancarlo; Pancrazzi, Maurizio; Pelizzo, Maria G.; Poletto, Luca; Sasso, Clementina; Schühle, Udo; Solanki, Sami K.; Strachan, Leonard; Susino, Roberto; Tondello, Giuseppe; Uslenghi, Michela; Woch, Joachim; Abbo, Lucia; Bemporad, Alessandro; Casti, Marta; Dolei, Sergio; Grimani, Catia; Messerotti, Mauro; Ricci, Marco; Straus, Thomas; Telloni, Daniele; Zuppella, Paola; Auchère, Frederic; Bruno, Roberto; Ciaravella, Angela; Corso, Alain J.; Alvarez Copano, Miguel; Aznar Cuadrado, Regina; D'Amicis, Raffaella; Enge, Reiner; Gravina, Alessio; Jejčič, Sonja; Lamy, Philippe; Lanzafame, Alessandro; Meierdierks, Thimo; Papagiannaki, Ioanna; Peter, Hardi; Fernandez Rico, German; Giday Sertsu, Mewael; Staub, Jan; Tsinganos, Kanaris; Velli, Marco; Ventura, Rita; Verroi, Enrico; Vial, Jean-Claude; Vives, Sebastien; Volpicelli, Antonio; Werner, Stephan; Zerr, Andreas; Negri, Barbara; Castronuovo, Marco; Gabrielli, Alessandro; Bertacin, Roberto; Carpentiero, Rita; Natalucci, Silvia; Marliani, Filippo; Cesa, Marco; Laget, Philippe; Morea, Danilo; Pieraccini, Stefano; Radaelli, Paolo; Sandri, Paolo; Sarra, Paolo; Cesare, Stefano; Del Forno, Felice; Massa, Ernesto; Montabone, Mauro; Mottini, Sergio; Quattropani, Daniele; Schillaci, Tiziano; Boccardo, Roberto; Brando, Rosario; Pandi, Arianna; Baietto, Cristian; Bertone, Riccardo; Alvarez-Herrero, Alberto; García Parejo, Pilar; Cebollero, María; Amoruso, Mauro; Centonze, Vito Bibcode: 2020A&A...642A..10A Altcode: 2019arXiv191108462A
Aims: Metis is the first solar coronagraph designed for a space mission and is capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona in a square field of view (FoV) of ±2.9° in width, with an inner circular FoV at 1.6°, thus spanning the solar atmosphere from 1.7 R⊙ to about 9 R⊙, owing to the eccentricity of the spacecraft orbit. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close (0.28 AU, at the closest perihelion) vantage point, achieving increasing out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, allow longer-term studies of the off-limb coronal features, thus finally disentangling their intrinsic evolution from effects due to solar rotation.
Methods: Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H I Lyman-α line at 121.6 nm. The visible light channel also includes a broadband polarimeter able to observe the linearly polarised component of the K corona. The coronal images in both the UV H I Lyman-α and polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15 000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 s can be achieved when observing coronal fluctuations in visible light.
Results: The Metis measurements, obtained from different latitudes, will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes the acceleration process and where the onset and initial propagation of coronal mass ejections (CMEs) take place. The near-Sun multi-wavelength coronal imaging performed with Metis, combined with the unique opportunities offered by the Solar Orbiter mission, can effectively address crucial issues of solar physics such as: the origin and heating/acceleration of the fast and slow solar wind streams; the origin, acceleration, and transport of the solar energetic particles; and the transient ejection of coronal mass and its evolution in the inner heliosphere, thus significantly improving our understanding of the region connecting the Sun to the heliosphere and of the processes generating and driving the solar wind and coronal mass ejections.
Conclusions: This paper presents the scientific objectives and requirements, the overall optical design of the Metis instrument, the thermo-mechanical design, and the processing and power unit; reports on the results of the campaigns dedicated to integration, alignment, and tests, and to the characterisation of the instrument performance; describes the operation concept, data handling, and software tools; and, finally, the diagnostic techniques to be applied to the data, as well as a brief description of the expected scientific products. The performance of the instrument measured during calibrations ensures that the scientific objectives of Metis can be pursued with success.

Metis website: http://metis.oato.inaf.it Title: Preface Authors: Bemporad, A.; Criscuoli, S.; Del Moro, D.; Guglielmino, S. L.; Landi, S.; Laurenza, M.; Reale, F.; Straus, T.; Vecchio, A. Bibcode: 2019NCimC..42....1B Altcode: No abstract at ADS Title: The third CO5BOLD workshop Authors: Straus, T.; Marconi, M.; Alcalà, J. M. Bibcode: 2017MmSAI..88....5S Altcode: No abstract at ADS Title: A virtual appliance as proxy pipeline for the Solar Orbiter/Metis coronagraph Authors: Pancrazzi, M.; Straus, T.; Andretta, V.; Spadaro, D.; Haugan, S. V.; de Groof, A.; Carr, R.; Focardi, M.; Nicolini, G.; Landini, F.; Baccani, C.; Romoli, M.; Antonucci, E. Bibcode: 2016SPIE.9913E..4LP Altcode: Metis is the coronagraph on board Solar Orbiter, the ESA mission devoted to the study of the Sun that will be launched in October 2018. Metis is designed to perform imaging of the solar corona in the UV at 121.6 nm and in the visible range where it will accomplish polarimetry studies thanks to a variable retarder plate. Due to mission constraints, the telemetry downlink on the spacecraft will be limited and data will be downloaded with delays that could reach, in the worst case, several months. In order to have a quick overview on the ongoing operations and to check the safety of the 10 instruments on board, a high-priority downlink channel has been foreseen to download a restricted amount of data. These so-called Low Latency Data will be downloaded daily and, since they could trigger possible actions, they have to be quickly processed on ground as soon as they are delivered. To do so, a proper processing pipeline has to be developed by each instrument. This tool will then be integrated in a single system at the ESA Science Operation Center that will receive the downloaded data by the Mission Operation Center. This paper will provide a brief overview of the on board processing and data produced by Metis and it will describe the proxy-pipeline currently under development to deal with the Metis low-latency data. Title: Testing Wave Propagation Properties in the Solar Chromosphere with ALMA and IRIS Authors: Fleck, Bernard; Straus, Thomas; Wedemeyer, Sven Bibcode: 2016SPD....47.0102F Altcode: Waves and oscillations are interesting not only from the point of view that they can propagate energy into the chromosphere and dissipate that energy to produce non-radiative heating, they also carry information about the structure of the atmosphere in which they propagate. Since the late 80s there is substantial evidence that the chromospheric wave field is dominated by a non-propagating component, presumably resulting from wave reflection at the transition region. Observations of Doppler oscillations measured in the Ca II infrared tripet lines, Ca II K, and He 10830 all show vanishing phase lags (i.e. vanishing travel time differences) between the various lines, in particular also for frequencies above the cut-off frequency. Why is the apparent phase speed of high frequency acoustic waves in the chromosphere so high? Are these results misleading because of complex radiation transfer effects in these optically thick lines? ALMA, which acts as a linear thermometer of the solar chromosphere, will provide measurements of the local plasma conditions that should be, at least in principle, much easier to interpret. Multi-wavelength time series of ALMA observations of the temperature fluctuations of inter-network oscillations should allow travel time measurements between different heights as these disturbances propagate through the chromosphere and thus should finally settle the long-standing question about the propagation characteristics of high frequency acoustic waves in the chromosphere. We plan to combine ALMA mm-observations with high resolution IRIS observations in the Mg II h and k lines, and until ALMA observations are available, will study the expected signals using time series of mm-maps from 3D radiation hydrodynamics simulations that are being prepared within the framework of the Solar Simulations for the Atacama Large Millimeter Observatory Network (SSALMON). Title: A steady-state supersonic downflow in the transition region above a sunspot umbra Authors: Straus, Thomas; Fleck, Bernhard; Andretta, Vincenzo Bibcode: 2015A&A...582A.116S Altcode: 2015arXiv150704279S We investigate a small-scale (~1.5 Mm along the slit), supersonic downflow of about 90 km s-1 in the transition region above the lightbridged sunspot umbra in AR 11836. The observations were obtained with the Interface Region Spectrograph (IRIS) on 2013 September 2 from 16:40 to 17:59 UT. The downflow shows up as redshifted "satellite" lines of the Si iv and O iv transition region lines and is remarkably steady over the observing period of nearly 80 min. The downflow is not visible in the chromospheric lines, which only show an intensity enhancement at the location of the downflow. The density inferred from the line ratio of the redshifted satellites of the O iv lines (Ne = 1010.6 ± 0.25 cm-3) is only a factor 2 smaller than the one inferred from the main components (Ne = 1010.95 ± 0.20 cm-3). Consequently, this implies a substantial mass flux (~5 × 10-7 g cm-2 s-1), which would evacuate the overlying corona on timescales close to 10 s. We interpret these findings as evidence of a stationary termination shock of a supersonic siphon flow in a cool loop that is rooted in the central umbra of the spot.

The movie is available in electronic form at http://www.aanda.org Title: Observations of a Steady-State Supersonic Downflow in the Transition Region above a Sunspot Umbra Authors: Fleck, Bernhard; Straus, Thomas; Andretta, Vincenzo Bibcode: 2015TESS....120311F Altcode: Sunspots have been an area of intense research ever since Hale's discovery of strong magnetic fields in these structures. Here we report on the detection of a particular sunspot phenomenon: a small-scale (~ 1.5 Mm), supersonic downflow of about 90 km/s in the transition region above a light-bridged sunspot umbra. The observations were obtained with the Interface Imaging Region Spectrograph (IRIS) on 2 September 2013 from 16:39 to 17:58 UT in the sunspot of AR 11836 near disk center. Slit length and width were 68” and 0.166”, respectively. The cadence of the time series was 3 s, with exposure times of 2 s. The observations comprise nine spectral windows: C II 1336, Fe XII 1349, Cl I 1352, O I 1356, Si IV 1394, Si IV 1403, NUV at 2786 and 2831, and Mg II h and k 2796. The spectral window containing the Si IV 1403 line also includes the O IV 1400, 1401, and 1405 lines, the last one blended with a S IV line. The downflow shows up as red-shifted, well-separated “satellite” lines of the Si IV and O IV transition region lines and is remarkably steady over the observing period of nearly 80 min. The satellite lines do not participate in the 3-min shock wave Doppler maneuvres of the main component. The downflow is not visible in the chromospheric lines, which only show an intensity enhancement at the location of the downflow. The density inferred from the line ratio of the redshifted satellites of the O IV lines (Ne=1010.5 ±0.3 cm-3) is only a factor 2.5 smaller than the one inferred from the main components (Ne=1010.9 ±0.2 cm-3). Consequently, this implies a substantial mass flux (~ 4×10-7 g cm-2 s-1), which would evacuate the overlying corona on time scales of the order of 10 s. We interpret these findings as evidence of a stationary termination shock of a supersonic siphon flow in a cool loop rooted in the central umbra of the spot. Such stationary shocks have been predicted for siphon flows in hot coronal loops by Noci (1981). Title: Wave Propagation in the Internetwork Chromosphere: Comparing IRIS Observations of Mg II h and k with Simulations Authors: Fleck, B.; De Pontieu, B.; Leenaarts, J.; Pereira, T. M. D.; Straus, T. Bibcode: 2014AGUFMSH51C4174F Altcode: The objective of this study is to explore the dynamics of the upper internetwork chromosphere using high-resolution spectroscopic "sit-and-stare" time series obtained with the Interface Region Imaging Spectrogragh (IRIS) in the Mg II h and k lines. The Mg II h and k lines reveal a particularly complex spatio-temporal behavior, which strongly depends on the magnetic field topology. We focus on six parameters in both the h and k line: the Doppler shift and intensity of the central reversal (h3 and k3) and the blue and red emission peaks (h2v, h2r, k2v, k2r). In an effort to better understand what physical parameters can be extracted from these lines and to put our interpretation of the observations on more solid grounds, we extend our analysis to synthetic spectra obtained from numerical simulations and compare the results to the observations. Title: On-board CME detection algorithm for the Solar Orbiter-METIS coronagraph Authors: Bemporad, A.; Andretta, V.; Pancrazzi, M.; Focardi, M.; Straus, T.; Sasso, C.; Spadaro, D.; Uslenghi, M.; Antonucci, E.; Fineschi, S.; Abbo, L.; Nicolini, G.; Landini, F.; Romoli, M.; Naletto, G.; Nicolosi, P. Bibcode: 2014SPIE.9152E..0KB Altcode: The METIS coronagraph is one of the instruments part of the payload of the ESA - Solar Orbiter mission to be launched in 2017. The spacecraft will operate much like a planetary encounter mission, with the main scientific activity taking place with the remote-sensing instruments during three 10-days intervals per orbit: optimization of the different instrument observing modes will be crucial. One of the key scientific targets of METIS will be the study of transient ejections of mass through the solar corona (Coronal Mass Ejections - CMEs) and their heliospheric evolution. METIS will provide for the first time imaging of CMEs in two different wavelengths: VL (visible light 580- 640 nm) and UV (Lyman-α line of HI at 121.6 nm). The detection of transient phenomena shall be managed directly by the METIS Processing and Power Unit (MPPU) by means of both external triggers ("flags") coming from other Solar Orbiter instruments, and internal "flags" produced directly by the METIS on-board software. METIS on-board algorithm for the automatic detection of CMEs will be based on running differences between consecutive images re-binned to very low resolution and thresholded for significant changes over a minimum value. Given the small relative variation of white light intensity during CMEs, the algorithm will take advantage of VL images acquired with different polarization angles to maximize the detection capability: possible false detections should be automatically managed by the algorithm. The algorithm will be able to provide the CME first detection time, latitudinal direction of propagation on the plane of the sky (within 45 degrees), a binary flag indicating whether a "halo CME" has been detected. Title: On-board detection and removal of cosmic ray and solar energetic particle signatures for the Solar Orbiter-METIS coronagraph Authors: Andretta, V.; Bemporad, A.; Focardi, M.; Grimani, C.; Landini, F.; Pancrazzi, M.; Sasso, C.; Spadaro, D.; Straus, T.; Uslenghi, M. C.; Antonucci, E.; Fineschi, S.; Naletto, G.; Nicolini, G.; Nicolosi, P.; Romoli, M. Bibcode: 2014SPIE.9152E..2QA Altcode: METIS is part of the science payload of Solar Orbiter. It is a coronagraph designed to obtain images of the outer solar corona both in the visible 580-640 nm band and in the UV, in a narrow band centered around the hydrogen Lyman-α line. We describe the main features of the procedures to remove signatures due to cosmic rays (CRs) and to solar energetic particles (SEPs) comparing them with alternatives in other contexts and in other solar coronagraphic missions. Our analysis starts from a realistic assessment of the radiation environment where the instrument is expected to operate, which is characteristic of the interplanetary space of the inner solar system, but quite unusual for most solar missions. Title: On the Signatures of Waves and Oscillations in IRIS Observations Authors: Fleck, Bernard; Straus, Thomas; De Pontieu, Bart; Leenaarts, Jorrit; Pereira, Tiago M. D. Bibcode: 2014AAS...22432305F Altcode: The objective of this study is to explore the signatures of acoustic waves and oscillations in a variety of magnetic field configurations in the Sun’s atmosphere using high-resolution spectroscopic “sit-an-stare” time series obtained with the Interface Region Imaging Spectrogragh (IRIS) in lines formed in the chromosphere and lower transition region (C II 1335 & 1336, C I 1352, O I 1356, Si IV 1394 & 1403 and Mg h and k). The occurrence of oscillations in the transition region is found to strongly depend on the magnetic field topology. The Mg h and k lines reveal a particularly complex spatio-temporal behavior. In an effort to better understand what physical parameters can be extracted from these lines, we extend our analysis to synthetic spectra obtained from numerical simulations and compare the results to observations. Title: The Intensity-Velocity Phase Spectra of Evanescent Oscillations and Acoustic Sources Authors: Severino, G.; Straus, T.; Oliviero, M.; Steffen, M.; Fleck, B. Bibcode: 2013SoPh..284..297S Altcode: 2012SoPh..tmp..295S There are three major issues in modeling solar evanescent oscillations: the variation of the intensity [I]-velocity [V] phase difference of p-modes close to the base of photosphere; the existence of a plateau of negative I-V phase differences below and between the ridges of the low-frequency p-modes; the explanation of the I-V cross-spectra of the evanescent oscillations. We present new interpretations for the first two issues, based on modeling intensity fluctuations taking steep temperature gradients, opacity, and non-adiabatic cooling into account. Title: On the Effects of the SDO Orbital Motion on the HMI Vector Magnetic Field Measurements Authors: Fleck, B.; Centeno, R.; Cheung, M.; Couvidat, S.; Hayashi, K.; Rezaei, R.; Steiner, O.; Straus, T. Bibcode: 2013enss.confE.145F Altcode: In a previous study we have investigated the magnetic field diagnostics potential of SDO/HMI. We have used the output of high-resolution 3D, time-dependent, radiative magneto-hydrodynamics simulations to calculate Stokes profiles for the Fe I 6173 Å line. From these we constructed Stokes filtergrams using a representative set of HMI filter response functions. The magnetic field vector (x,y) and line-of-sight Doppler velocities V(x,y) were determined from these filtergrams using a simplified version of the HMI magnetic field processing pipeline, and the reconstructed magnetic field (x,y) and line-of-sight velocity V(x,y) were compared to the actual magnetic field (x,y,z) and vertical velocity V0(x,y,z) in the simulations. The present investigation expands this analysis to include the effects of the significant orbital motions of SDO, which, given the limited wavelength range of the HMI filter profiles, affects the outer wing measurements and therefore might impact the magnetic field measurements. We find that the effects of the orbital movement of SDO are noticeable, in particular for the strongest fields (B > 3 kG) and the maximum wavelength shift of 5.5 km/s (3.5 km/s orbital movement + 2 km/s solar rotation). Saturation effects for strong fields (B > 3 kG) are already visible for wavelength shifts of 3.2 km/s (orbital movement, disk center). The measurements of inclination and vertical velocity are more robust. Compared to other factors of uncertainty in the inversion of HMI Stokes measurements the orbital movement is not a major concern or source of error. Title: Acoustic-Gravity Waves in the Solar Atmosphere: Comparing Hinode/SP Observations with Numerical Simulations Authors: Fleck, Bernard; Straus, T.; Severino, G. Bibcode: 2012AAS...22020121F Altcode: We investigate the signatures of acoustic-gravity waves in Hinode/SP observations and compare them to those found in line spectra synthesized from high-resolution 3D radiation-hydrodynamics simulations. The Hinode/SP time series extends over 4 hours, with a cadence of 16 s and a spatial resolution of 0.16 arcsec/pixel. The observations are compared to two numerical simulations of the Sun’s surface layers, both computed with the radiation hydrodynamics code CO5BOLD. The higher resolution simulation has a fixed 3D Cartesian grid with 400 x 400 x 300 cells, each of size 14 km x 14 km x 7.5 km, the lower resolution simulation 200 x 200 x 250 cells, each of size 56 km x 56 km x 21 km. The higher resolution simulation thus covers a cube of 5.6 x 5.6 x 2.3 Mm3, the lower resolution simulation a cube of size 11.2 x 11.2 x 5.2 Mm3. A line-synthesis code, based on the assumption of local thermodynamic equilibrium (LTE), was fed with the physical parameters of the simulations to produce synthetic, two-dimensional spectra of the photospheric lines of Fe 6301/6302 Å (Hinode/SP), Fe 6173 Å (SDO/ HMI), and Ni 6768 Å (SOHO/MDI). The resulting Doppler velocity time series are analyzed using Fourier techniques and compared to the observed Hinode/SP spectra. The height-dependent energy flux in the simulations is determined in the acoustic, evanescent and internal gravity wave regime and compared to energy flux estimates from the Hinode observations and the synthesized Doppler velocities of the simulations. Title: On The Magnetic-Field Diagnostics Potential of SDO/HMI Authors: Fleck, Bernard; Hayashi, K.; Rezaei, R.; Vitas, N.; Centeno, R.; Cheung, M.; Couvidat, S.; Fischer, C.; Steiner, O.; Straus, T.; Viticchie, B. Bibcode: 2012AAS...22020701F Altcode: The Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) is designed to study oscillations and the magnetic field in the solar photosphere. It observes the full solar disk in the Fe I absorption line at 6173 Å. We use the output of three high-resolution 3D, time-dependent, radiative magneto-hydrodynamics simulations (two based on the MURaM code, one on the CO5BOLD code) to calculate Stokes profiles for the Fe I 6173 Å line for snapshots of a sunspot, a plage area and an enhanced network region. Stokes filtergrams are constructed for the 6 nominal HMI wavelengths by multiplying the Stokes profiles with a representative set of HMI filter response functions. The magnetic field vector B(x,y) and line-of-sight Doppler velocities V(x,y) are determined from these filtergrams using a simplified version of the HMI magnetic field processing pipeline. Finally, the reconstructed magnetic field B(x,y) and line-of-sight velocity V(x,y) are compared to the actual magnetic field B0(x,y,z) and vertical velocity V0(x,y,z) in the simulations. Title: On the Magnetic-Field Diagnostics Potential of SDO/HMI Authors: Fleck, B.; Hayashi, K.; Rezaei, R.; Vitas, N.; Centeno, R.; Cheung, M.; Couvidat, S.; Fischer, C.; Steiner, O.; Straus, T.; Viticchie, B. Bibcode: 2012decs.confE.104F Altcode: The Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) is designed to study oscillations and the magnetic field in the solar photosphere. It observes the full solar disk in the Fe I absorption line at 6173 Å. We use the output of three high-resolution 3D, time-dependent, radiative magneto-hydrodynamics simulations (two based on the MURaM code, one on the CO5BOLD code) to calculate Stokes profiles Fi(λ,x,y; i=I, V, Q, U) for the Fe I 6173 Å line for snapshots of a sunspot, a plage area and an enhanced network region. Stokes filtergrams are constructed for the 6 nominal HMI wavelengths by multiplying the Stokes profiles with a representative set of HMI filter response functions. The magnetic field vector B(x,y) and line-of-sight Doppler velocities V(x,y) are determined from these filtergrams using a simplified version of the HMI magnetic field processing pipeline. Finally, the reconstructed magnetic field B(x,y) and line-of-sight velocity V(x,y) are compared to the actual magnetic field B0(x,y,z) and vertical velocity V0(x,y,z) in the simulations. Title: On the Magnetic-Field Diagnostics Potential of SDO/HMI Authors: Fleck, B.; Hayashi, K.; Rezaei, R.; Vitas, N.; Centeno, R.; Couvidat, S.; Fischer, C.; Steiner, O.; Straus, T.; Viticchie, B. Bibcode: 2011sdmi.confE..74F Altcode: The Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) is designed to study oscillations and the magnetic field in the solar photosphere. It observes the full solar disk in the Fe I 6173 absorption line. We use the output of two high-resolution 3D, time-dependent, radiative magneto-hydrodynamics simulations (one based on the MURAM code, the other one on the COBOLD code) to calculate Stokes profiles for the Fe I 6173 line for a snapshot of a plage region and a snapshot of an enhanced network region. After spatially degrading the Stokes profiles to HMI resolution, they are multiplied by a representative set of HMI filter response functions and Stokes filtergrams are constructed for the 6 nominal HMI wavelengths. The magnetic field vector and line-of-sight Doppler velocities are determined from these filtergrams using a simplified version of the HMI magnetic field processing pipeline. Finally, the reconstructed magnetic field is compared to the actual magnetic field in the simulation. Title: On the Formation Height of the SDO/HMI Fe 6173 Å Doppler Signal Authors: Fleck, B.; Couvidat, S.; Straus, T. Bibcode: 2011SoPh..271...27F Altcode: 2011SoPh..tmp..242F; 2011arXiv1104.5166F; 2011SoPh..tmp..117F; 2011SoPh..tmp..173F The Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) is designed to study oscillations and the magnetic field in the solar photosphere. It observes the full solar disk in the Fe I absorption line at 6173 Å. We use the output of a high-resolution, 3D, time-dependent, radiation-hydrodynamic simulation based on the CO5BOLD code to calculate profiles F(λ,x,y,t) for the Fe I 6173 Å line. The emerging profiles F(λ,x,y,t) are multiplied by a representative set of HMI filter-transmission profiles Ri(λ, 1≤i≤6) and filtergrams Ii(x,y,t; 1≤i≤6) are constructed for six wavelengths. Doppler velocities VHMI(x,y,t) are determined from these filtergrams using a simplified version of the HMI pipeline. The Doppler velocities are correlated with the original velocities in the simulated atmosphere. The cross-correlation peaks near 100 km, suggesting that the HMI Doppler velocity signal is formed rather low in the solar atmosphere. The same analysis is performed for the SOHO/MDI Ni I line at 6768 Å. The MDI Doppler signal is formed slightly higher at around 125 km. Taking into account the limited spatial resolution of the instruments, the apparent formation height of both the HMI and MDI Doppler signal increases by 40 to 50 km. We also study how uncertainties in the HMI filter-transmission profiles affect the calculated velocities. Title: High-frequency Waves in Numerical Simulations of the Solar Atmosphere Authors: Fleck, Bernard; Straus, T.; Severino, G. Bibcode: 2011SPD....42.1720F Altcode: 2011BAAS..43S.1720F We investigate the excitation processes, propagation characteristics, and energy transport of high-frequency waves in the solar atmosphere with the help of high-resolution 3D radiation-hydrodynamics simulations. Time series of synthetic spectra of four photospheric Fraunhofer lines (Fe 6302, Fe 6301, Fe 6173, Ni 6768) from these simulations are analyzed in order to evaluate the diagnostic power of spectroscopic observations. Title: Estimating the Energy Flux of Acoustic-Gravity Waves in the Solar Atmosphere from SDO/HMI Data Authors: Fleck, B.; Straus, T.; Jefferies, S.; Scherrer, P. Bibcode: 2010AGUFMSH11A1602F Altcode: Straus et al. (2008, 2009) demonstrated the existence of internal gravity waves in the solar atmosphere and showed that they are a key mediator of mechanical energy in the middle/upper photosphere, transporting even more energy than high-frequency acoustic waves. Here we repeat this analysis with data from SDO/HMI, which offers several distinct advantages, which are particularly relevant for the study of internal gravity waves (which have long periods and small spatial scales): excellent image stability over long time intervals, high spatial resolution, large field-of-view, and good temporal cadence. Title: On the Origin of High-Frequency "Acoustic'' Power in Photospheric and Chromospheric Velocity Power Spectra Authors: Fleck, Bernard; Straus, T.; Carlsson, M.; Jefferies, S. M.; Severino, G.; Tarbell, T. D. Bibcode: 2010AAS...21640309F Altcode: 2010BAAS...41..879F In a recent paper (Fleck et al., 2010) we compared observed Dopplergram time series from Hinode with results from 3-D numerical simulations based on the Oslo "Stagger” and CO5BOLD codes. Given the rapid falloff of atmospheric modulation transfer functions at high frequencies due to the extended widths of typical velocity response functions, one would expect the high-frequency tail of Doppler power spectra to drop significantly below those of actual velocities at the corresponding heights in the simulations. Surprisingly, our analysis of power spectra of Doppler shifts of simulated line profiles did not reveal such a steep falloff at high frequencies. Instead, they are comparable to (and in some cases even larger than) those of the actual velocities, making estimates of the energy flux of high frequency acoustic waves questionable, in particular those that apply atmospheric MTF corrections. In this work we study the cause of this unexpected behavior in detail, with particular emphasis on the role of rapidly changing velocity response functions in a dynamic atmosphere with strong vertical velocity gradients. Title: High frequency waves in the solar atmosphere?. Authors: Fleck, B.; Straus, T.; Carlsson, M.; Jefferies, S. M.; Severino, G.; Tarbell, T. D. Bibcode: 2010MmSAI..81..777F Altcode: 2010arXiv1002.3285F The present study addresses the following questions: How representative of the actual velocities in the solar atmosphere are the Doppler shifts of spectral lines? How reliable is the velocity signal derived from narrowband filtergrams? How well defined is the height of the measured Doppler signal? Why do phase difference spectra always pull to 0o phase lag at high frequencies? Can we actually observe high frequency waves (P< 70 s)? What is the atmospheric MTF of high frequency waves? How reliably can we determine the energy flux of high frequency waves? We address these questions by comparing observations obtained with Hinode/NFI with results from two 3D numerical simulations (Oslo Stagger and CO5BOLD). Our results suggest that the observed high frequency Doppler velocity signal is caused by rapid height variations of the velocity response function in an atmosphere with strong velocity gradients and cannot be interpreted as evidence of propagating high frequency acoustic waves. Estimates of the energy flux of high frequency waves should be treated with caution, in particular those that apply atmospheric MTF corrections. Title: On the Role of Acoustic-Gravity Waves in the Energetics of the Solar Atmosphere Authors: Straus, T.; Fleck, B.; Jefferies, S. M.; McIntosh, S. W.; Severino, G.; Steffen, M.; Tarbell, T. D. Bibcode: 2009ASPC..415...95S Altcode: 2010arXiv1003.3773S In a recent paper (Straus et al. 2008) we determined the energy flux of internal gravity waves in the lower solar atmosphere using a combination of 3D numerical simulations and observations obtained with the IBIS instrument operated at the Dunn Solar Telescope and the Michelson Doppler Imager (MDI) on SOHO. In this paper we extend these studies using coordinated observations from SOT/NFI and SOT/SP on Hinode and MDI. The new measurements confirm that gravity waves are the dominant phenomenon in the quiet middle/upper photosphere and that they transport more mechanical energy than the high-frequency (> 5 mHz) acoustic waves, even though we find an acoustic flux 3-5 times larger than the upper limit estimate of Fossum & Carlsson (2006). It therefore appears justified to reconsider the significance of (non-M)HD waves for the energy balance of the solar chromosphere. Title: On The Interpretation Of Hinode NFI Filtergrams Authors: Fleck, Bernard; Straus, T.; Jefferies, S. M.; Severino, G.; Tarbell, T. D. Bibcode: 2009SPD....40.0927F Altcode: Phase difference spectra between the velocity signals at two different heights represent a powerful tool to study the propagation characteristics of acoustic-gravity waves in the solar atmosphere. In our efforts to study the dynamics and energetics of these waves we have acquired high-resolution, high-cadence time series with Hinode SOT/NFI at two different levels in the Mg b2 or Na D1 lines. The observed phase spectra between the velocity signals derived from the "wing" and "core" filtergrams of these lines do not show the expected behavior. This points to (a) a fundamental lack of understanding of the propagation characteristics of acoustic waves, which may be more complex than commonly assumed, or (b) significant difficulties in interpreting filtergrams taken at fixed wavelengths in the wings of an absorption line, possibly limiting the diagnostic potential of Doppler "velocity" measurements from such filtergrams. The present work aims at disentangling these effects with the help of numerical simulations. Title: High Frequency Acoustic Waves in the Sun's Atmosphere Authors: Fleck, B.; Jefferies, S. M.; McIntosh, S. W.; Severino, G.; Straus, T.; Tarbell, T. D. Bibcode: 2008ESPM...12.2.39F Altcode: This year marks the 60th anniversary of two pioneering papers by Schwarzschild (1948) and Biermann (1948), who independently proposed that acoustic waves generated in the turbulent convection zone play an important role in the heating of the chromosphere and corona. High frequency acoustic waves have remained one of the leading contenders for solving the heating problem of the non-magnetic chromospheres of the Sun and late-type stars ever since. Earlier attempts to determine the acoustic energy flux from ground were compromised by atmospheric seeing, which has its biggest effect on the high frequency parts of the observed signal. Recently, based on a comparison of TRACE observations and 1-D simulations, Fossum & Carlsson (2005, 2006) concluded that high-frequency acoustic waves are not sufficient to heat the solar chromosphere. The same conclusion was reached by Carlsson et al. (2007) from an analysis of Hinode SOT/BFI Ca II H and blue continuum observations. Other authors (e.g. Cuntz et al. 2007; Wedemeyer-Boehm et al. 2007, Kalkofen 2007), however, questioned these results for a number of reasons. Because of its limited spatial resolution and limited sensitivity there are inherent difficulties when comparing TRACE observations with numerical simulations. Further, intensity oscillations are difficult to interpret, as they result from a phase-sensitive mix of temperature and pressure fluctuations, and non-local radiation transfer effects may complicate the picture even more. Here we revisit the role of high frequency acoustic waves in the dynamics and energetics of the Sun's atmosphere using high cadence, high resolution Doppler velocity measurements obtained with SOT/SP and SOT/NFI on Hinode. Title: Spatio-Temporal Analysis of Photospheric Turbulent Velocity Fields Using the Proper Orthogonal Decomposition Authors: Vecchio, A.; Carbone, V.; Lepreti, F.; Primavera, L.; Sorriso-Valvo, L.; Straus, T.; Veltri, P. Bibcode: 2008SoPh..251..163V Altcode: 2008SoPh..tmp...40V The spatio-temporal dynamics of the solar photosphere are studied by performing a proper orthogonal decomposition (POD) of line-of-sight velocity fields computed from high-resolution data coming from the SOHO/MDI instrument. Using this technique, we are able to identify and characterize the different dynamical regimes acting in the system. All of the POD modes are characterized by two well-separated peaks in the frequency spectra. In particular, low-frequency oscillations, with frequencies in the range 20 - 130 μHz, dominate the most energetic POD modes (excluding solar rotation) and are characterized by spatial patterns with typical scales of about 3 Mm. Patterns with larger typical scales, of about 10 Mm, are dominated by p-mode oscillations at frequencies of about 3000 μHz. The p-mode properties found by POD are in agreement with those obtained with the classical Fourier analysis. The spatial properties of high-energy POD modes suggest the presence of a strong coupling between low-frequency modes and turbulent convection. Title: On the Role of Acoustic-gravity Waves in the Energetics of the Solar Atmosphere Authors: Straus, T.; Fleck, B.; Jefferies, S. M.; Cauzzi, G.; McIntosh, S. W.; Reardon, K.; Severino, G.; Steffen, M.; Suter, M.; Tarbell, T. D. Bibcode: 2008ESPM...12.2.11S Altcode: We revisit the dynamics and energetics of the solar atmosphere, using a combination of high-quality observations and 3D numerical simulations of the overshoot region of compressible convection into the stable photosphere. We discuss the contribution of acoustic-gravity waves to the energy balance of the photosphere and low chromosphere. We demonstrate the presence of propagating internal gravity waves at low frequencies (< 5mHz). Surprisingly, these waves are found to be the dominant phenomenon in the quiet middle/upper photosphere and to transport a significant amount of mechanical energy into the atmosphere outweighing the contribution of high-frequency (> 5mHz) acoustic waves by more than an order of magnitude. We compare the properties of high-frequency waves in the simulations with results of recent high cadence, high resolution Doppler velocity measurements obtained with SOT/SP and SOT/NFI on Hinode. Our results seem to be in conflict with the simple picture of upward propagating sound waves. We discuss the implications of our findings on the energy flux estimate at high-frequencies. Title: Velocity and Intensity Power and Cross Spectra in Numerical Simulations of Solar Convection Authors: Severino, G.; Straus, T.; Steffen, M. Bibcode: 2008SoPh..251..549S Altcode: 2008SoPh..tmp...54S Fitting observed power and cross spectra of medium-degree p modes in velocity (V) and intensity (I) has been widely used for getting information about the p-mode excitation process and, in particular, for trying to determine the type and location of the acoustic sources. Numerical simulations of solar convection allow one to "observe" velocity and temperature (T, used as proxy for I) fluctuations in different reference frames. Sampling the oscillations on planes of constant optical depth (τ-frame) closely corresponds to the observer's point of view, whereas sampling the oscillations at constant geometrical height (z-frame) is more appropriate for comparison with predictions from theoretical models based on Eulerian hydrodynamics. The results of the analysis in the two frames show significant differences. Considering the effects introduced on oscillations by the steep temperature gradient of the photosphere and by the temperature- and pressure-dependent continuum opacity, we develop a new model for fitting the simulated V and T power and cross spectra both in the τ- and z-frames and discuss its merits and limitations. Title: The Energy Flux of Internal Gravity Waves in the Lower Solar Atmosphere Authors: Straus, Thomas; Fleck, Bernhard; Jefferies, Stuart M.; Cauzzi, Gianna; McIntosh, Scott W.; Reardon, Kevin; Severino, Giuseppe; Steffen, Matthias Bibcode: 2008ApJ...681L.125S Altcode: Stably stratified fluids, such as stellar and planetary atmospheres, can support and propagate gravity waves. On Earth these waves, which can transport energy and momentum over large distances and can trigger convection, contribute to the formation of our weather and global climate. Gravity waves also play a pivotal role in planetary sciences and modern stellar physics. They have also been proposed as an agent for the heating of stellar atmospheres and coronae, the exact mechanism behind which is one of the outstanding puzzles in solar and stellar physics. Using a combination of high-quality observations and 3D numerical simulations we have the first unambiguous detection of propagating gravity waves in the Sun's (and hence a stellar) atmosphere. Moreover, we are able to determine the height dependence of their energy flux and find that at the base of the Sun's chromosphere it is around 5 kW m-2. This amount of energy is comparable to the radiative losses of the entire chromosphere and points to internal gravity waves as a key mediator of energy into the solar atmosphere. Title: High Frequency Acoustic Waves in the Sun's Atmosphere Authors: Fleck, B.; Jefferies, S. M.; McIntosh, S. W.; Straus, T.; Tarbell, T. D. Bibcode: 2008AGUSMSP41B..04F Altcode: This year marks the 60th anniversary of two pioneering papers by Schwarzschild (1948) and Biermann (1948), who independently proposed that acoustic waves generated in the turbulent convection zone play an important role in the heating of the chromosphere and corona. High frequency acoustic waves have remained one of the leading contenders for solving the heating problem of the non-magnetic chromospheres of the Sun and late-type stars ever since. Earlier attempts to determine the acoustic energy flux from ground were compromised by atmospheric seeing, which has its biggest effect on the high frequency parts of the observed signal. Recently, based on a comparison of TRACE observations and 1-D simulations, Fossum & Carlsson (2005, 2006) concluded that high-frequency acoustic waves are not sufficient to heat the solar chromosphere. The same conclusion was reached by Carlsson et al. (2007) from an analysis of Hinode SOT/BFI Ca II H and blue continuum observations. Other authors (e.g. Cuntz et al. 2007; Wedemeyer-Boehm et al. 2007, Kalkofen 2007), however, questioned these results for a number of reasons. Because of its limited spatial resolution and limited sensitivity there are inherent difficulties when comparing TRACE observations with numerical simulations. Further, intensity oscillations are difficult to interpret, as they result from a phase-sensitive mix of density, temperature, and pressure fluctuations, and radiation transfer effects may complicate the picture even more. Here we revisit the role of high frequency acoustic waves in the Sun's atmosphere using high cadence, high resolution Doppler velocity measurements obtained with SOT/SP and SOT/NFI on Hinode. Title: Internal Gravity Waves and their Role in the Energetics of the Solar Atmosphere Authors: Fleck, Bernard; Straus, T.; Jefferies, S.; McIntosh, S. W.; Severino, G.; Steffen, M. Bibcode: 2007AAS...210.2410F Altcode: 2007BAAS...39..130F Internal gravity waves are believed to be excited by convective overshoot in the solar atmosphere. We compare the results from numerical simulations of the overshoot region of compressible convection into a stable photosphere, with observations of the velocity field at several heights in the solar atmosphere. We find a consistent picture for the quiet middle/upper photosphere in which internal gravity waves are the dominant phenomenon at low frequencies (< 2.5 mHz). We estimate the contribution of these waves to the energy balance in the photosphere and low chromosphere. Title: Resonant Oscillation Modes and Background in Realistic Hydrodynamical Simulations of Solar Surface Convection Authors: Straus, T.; Severino, G.; Steffen, M. Bibcode: 2006ESASP.617E...4S Altcode: 2006soho...17E...4S No abstract at ADS Title: SOLARNET-Italian Solar Archive Federation. The First Italian Virtual Observatory Application Authors: Volpicelli, C. A.; Antonucci, E.; Cora, A.; Giordano, S.; Messerotti, M.; Santin, A.; Zlobec, P.; Severino, G.; Oliviero, M.; DeMarino, I.; Alvino, R.; Straus, T.; Ermolli, I.; Centrone, C.; Perna, C.; Zuccarello, F.; Romano, P.; Spadaro, D.; Contarino, L. Bibcode: 2006MSAIS...9..129V Altcode: We describe the implementation of the national project SOLARNET (SOLar ARchive NETwork) aimed at federating the heterogeneous Italian solar data archives into a VO (Virtual Observatory) framework as a single integrated database, and providing users with tools to search and retrieve specific data sets. It interoperates using the SOAP/XML Web Services exposed by each single node and managed via a unified Portal.This project is the first real Italian Virtual Observatory application using the standard defined by the IVOA (International Virtual Observatory Alliance) working groups. Title: A model of intensity and velocity power and I-V phase difference across p-mode line profile based on a forced damped harmonic oscillator and on the observed coherence spectrum Authors: Magri, Maria; Oliviero, Maurizio; Severino, Giuseppe; Straus, Thomas Bibcode: 2001MmSAI..72..511M Altcode: We develop a simple model, based on a damped harmonic oscillator excited by a random forcing, with the aim to reproduce the observed trends in the intensity I and velocity V power and in the I-V phase difference and coherence spectra. The model accounts for an oscillation mode embedded in a solar background which is partly correlated to the mode. The complex vectors I and V and the corresponding power spectra and I-V phase difference are computed. The observed power spectra and the I-V phase difference in the frequencies range 2.245 - 2.275 mHz for l = 17 (GONG data) are used as a comparison. We can also reproduce the trend of the observed coherence. The obtained results are quite stimulating to understand how the correlated convective background affects the data and what fraction of the convective background is correlated to the mode. Title: Recent results on the solar photospheric dynamics Authors: Severino, Giuseppe; Magri, Maria; Oliviero, Maurizio; Straus, Thomas Bibcode: 2001MmSAI..72..677S Altcode: The solar photosphere is a relatively small atmospheric layer, that is a boundary between the convective interior and the optically thin and magnetic outer atmosphere, where convection overshoots into and different types of waves are excited and damped. Such a system cannot be described by a simple dynamical model. Recent progress in the study of the solar photospheric dynamics has been obtained thanks to the space-time analysis of the velocity (V) and intensity (I) fluctuations measured by the GONG, MDI/SOHO and VAMOS experiments. In particular, it is claimed that the I-V phase differences and coherence can allow to identify the seismic events which are thought to excite the solar global oscillations. Title: The photosphere - region of reflection and excitation of solar oscillations Authors: Straus, Thomas; Severino, Giuseppe Bibcode: 2001MmSAI..72..533S Altcode: Two observational facts have enforced the interest in the solar p-mode background spectrum in the recent past: the opposite asymmetry of the p-mode profiles in intensity and velocity, and the particular behavior of the I-V phase difference in the transition from the background to the p-mode across the line profiles. We give a short review on the current status of the investigation of the solar background. Title: I-V phase difference and gain analysis of GONG full-disk data Authors: Oliviero, M.; Severino, G.; Straus, T.; Jefferies, S. M.; Appourchaux, T. Bibcode: 2000MmSAI..71..999O Altcode: No abstract at ADS Title: Calibration of VAMOS Magnetic Data Authors: Vogt, E.; Oliviero, M.; Severino, G.; Straus, T. Bibcode: 1999ESASP.448..405V Altcode: 1999ESPM....9..405V; 1999mfsp.conf..405V No abstract at ADS Title: Wavelet Analysis of Spatial Coherent Structures in the Photosphere Authors: Pietropaolo, E.; Berrilli, F.; Consolini, G.; Smaldone, L. A.; Straus, T.; Cauzzi, G.; Bruno, R.; Bavassano, B. Bibcode: 1999ESASP.448..343P Altcode: 1999ESPM....9..343P; 1999mfsp.conf..343P No abstract at ADS Title: Properties of solar granulation cells in quiet regions as derived from a time series of white light images Authors: Cauzzi, G.; Consolini, G.; Berrilli, F.; Smaldone, L. A.; Straus, T.; Bavassano, B.; Bruno, R.; Caccin, B.; Carbone, V.; Egidi, A.; Ermolli, I.; Florio, A.; Pietropaolo, E. Bibcode: 1998MmSAI..69..647C Altcode: No abstract at ADS Title: The Magneto-Optical Filter in Napoli: Perspectives and Test Observations Authors: Moretti, P. F.; Severino, G.; Cauzzi, G.; Reardon, K.; Straus, T.; Cacciani, A.; Marmolino, C.; Oliviero, M.; Smaldone, L. A. Bibcode: 1997ASSL..225..293M Altcode: 1997scor.proc..293M An observing station based on the Magneto-Optical-Filter (MOF) technology is being installed at Osservatorio Astronomico di Capodimonte, in Napoli. In this paper, the main characteristics and goals of this new instrument are discussed, and several velocity and magnetic observations from a test campaign are shown. Title: Dynamics of the solar photosphere. I. Two-dimensional spectroscopy of mesoscale phenomena. Authors: Straus, T.; Bonaccini, D. Bibcode: 1997A&A...324..704S Altcode: We address the "mesogranulation" phenomenon by analyzing a spectral time series, taken at disk center with a two-dimensional spectroscopy device and covering a period of 4 hours. This tunable device was composed by a Fabry-Perot interferometer mounted in tandem with an Universal Birefringent Filter (UBF). We calculate spatial power spectra, spatio-temporal k-ω power, phase difference and coherence spectra at different low photospheric levels, in order to investigate the nature of the mesoscale phenomena. At the lowest levels, mesostructures appear as a part of an extended distribution of granular sizes without further distinction from granulation. Here, the plasma flows are driven by convection. On the other hand, a different mesoscale phenomenon emerges at levels as high as approximately 200-300km above τ_5000_=1, at medium spatial (k=~0.5...2Mm^-1^) and medium temporal (ν=~0.5...1mHz) frequencies. This phenomenon is distinct from convection by its non-convective phase difference values ({PHI}_v-I_=~-30°, {PHI}_v-v_<0°) and by its different propagation character (almost horizontal propagation). By these properties, the mesoscale phenomena in the higher photosphere can be identified as internal gravity waves in the solar atmosphere. Title: ARTHEMIS: The Archive Project for the IPM and THEMIS Authors: Reardon, K.; Severino, G.; Cauzzi, G.; Gomez, M. T.; Straus, T.; Russo, G.; Smaldone, G.; Marmolino, C. Bibcode: 1997ASPC..118..398R Altcode: 1997fasp.conf..398R We describe the plan for ARTHEMIS, the italian archive for THEMIS, from the point of view of the prospective users of the archive. This archive is designed to store the data from the Italian Panoramic Monochromator (IPM) instrument installed on THEMIS as well as the full-disk images obtained by the telescope. We break the expected users down into seven categories: a) prospective IPM users; b) campaign planners; c) data analysts, d) external collaborators; e) instrument monitors, f) archival observers; and g) the general public. Title: ARTHEMIS: The archive project for the Italian Panoramic Monochromator Authors: Reardon, K.; Severino, G.; Cauzzi, G.; Gomez, M. T.; Straus, T.; Russo, G.; Smaldone, L. A.; Marmolino, C. Bibcode: 1997MmSAI..68..499R Altcode: No abstract at ADS Title: k-ω diagrams of the solar atmosphere revisited. Authors: Deubner, F. -L.; Fleck, B.; Schmitz, F.; Straus, T. Bibcode: 1990AGAb....5...35D Altcode: No abstract at ADS Title: Dynamics of mesogranulation. Authors: Straus, T.; Deubner, F. -L. Bibcode: 1990AGAb....5...34S Altcode: No abstract at ADS