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10. Observations of Substorm Electrodynamics Using the Miracle Network

Author

Syrjäsuo, M. T., primary, Pulkkinen, T. I., additional, Janhunen, P., additional, Viljanen, A., additional, Pellinen, R. J., additional, Kauristie, K., additional, Opgenoorth, H. J., additional, Wallman, S., additional, Eglitis, P., additional, Karlsson, P., additional, Amm, O., additional, Nielsen, E., additional, and Thomas, C., additional

Published
1998
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16. Interplanetary magnetic field rotations followed from L1 to the ground: The response of the Earth's magnetosphere as seen by multi-spacecraft and ground-based observations

Author

Volwerk, M., Berchem, J., Bogdanova, Y. V., Constantinescu, O. D., Dunlop, M. W., Eastwood, J. P., Escoubet, P., Fazakerley, A. N., Frey, H., Lavraud, B., Panov, E. V., Shen, C., Shi, J. K., Taylor, M. G. G. T., Wang, J., Wild, J. A., Zhang, Q. H., Amm, O., Weygand, J. M., and Hasegawa, Hiroshi

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Magnetosphere, 01 natural sciences, Magnetosheath, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Astrophysics::Solar and Stellar Astrophysics, lcsh:Science, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Geomagnetic storm, lcsh:QC801-809, Geology, Astronomy and Astrophysics, Geophysics, Bow shocks in astrophysics, lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, Polar wind, Space and Planetary Science, Magnetosphere of Saturn, Physics::Space Physics, Magnetopause, lcsh:Q, Astrophysics::Earth and Planetary Astrophysics, Magnetosphere of Jupiter, lcsh:Physics
Abstract

著者人数: 20名, Accepted: 2011-08-30, 資料番号: SA1002971000

Published
2011

18. Modulation of the substorm current wedge by bursty bulk flows : 8 September 2002- Revisited

Author

Palin, Laurianne, Opgenoorth, Hermann J., Ågren, K., Zivkovic, T., Sergeev, V. A., Kubyshkina, M. V., Nikolaev, A., Kauristie, K., van de Kamp, M., Amm, O., Milan, S. E., Imber, S. M., Facsko, G., Palmroth, M., Nakamura, R., Palin, Laurianne, Opgenoorth, Hermann J., Ågren, K., Zivkovic, T., Sergeev, V. A., Kubyshkina, M. V., Nikolaev, A., Kauristie, K., van de Kamp, M., Amm, O., Milan, S. E., Imber, S. M., Facsko, G., Palmroth, M., and Nakamura, R.

Abstract

The ultimate formation mechanism of the substorm current wedge (SCW) remains to date unclear. In this study, we investigate its relationship to plasma flows at substorm onset and throughout the following expansion phase. We revisit the case of 8 September 2002, which has been defined as one of the best textbook examples of a substorm because of its excellent coverage by both spacecraft in the magnetotail and ground-based observatories. We found that a dense sequence of arrival of nightside flux transfer events (NFTEs; which can be understood as the lobe magnetic signature due to a bursty bulk flow travelling earthward in the central plasma sheet) in the near-Earth tail leads to a modulation (and further step-like builtup) of the SCW intensity during the substorm expansion phase. In addition, we found that small SCWs are created also during the growth phase of the event in association with another less intense sequence of NFTEs. The differences between the sequence of NFTEs in the growth and expansion phase are discussed. We conclude that the envelope of the magnetic disturbances which we typically refer to as an intense magnetic substorm is the result of a group or sequence of more intense and more frequent NFTEs.

Published
2016
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19. Low- altitude electron acceleration due to multiple flow bursts in the magnetotail

Author

Nakamura, R., Karlsson, T., Hamrin, M., Nilsson, H., Marghitu, O., Amm, O., Bunescu, C., Constantinescu, V., Frey, H. U., Keiling, A., Semeter, J., Sorbalo, E., Vogt, J., Forsyth, C., and Kubyshkina, M. V.

Subjects
multiple flow burst, field-aligned current, Alfven waves, magnetosphere-ionosphere coupling, Geosciences, Multidisciplinary, Multidisciplinär geovetenskap
Abstract

At 10:00 UT on 25 February 2008, Cluster 1 spacecraft crossed the near-midnight auroral zone, at about 2R(E) altitude, while two of the Time History of Events and Macroscale Interactions During Substorms (THEMIS) spacecraft, THD and THE, observed multiple flow bursts on the near-conjugate plasma sheet field lines. The flow shear pattern at THEMIS was consistent with the vortical motion at duskside of a localized flow channel. Coinciding in time with the flow bursts, Cluster 1 observed bursts of counterstreaming electrons with mostly low energies (441eV), accompanied by short time scale ( First observation of multiple flow signatures on near-conjugate flux tubes Low-energy electron profile suggests Alfvenic acceleration due to fast flow Multiple flow bursts are obtained to extend over large radial distance in tail

Published
2014

20. Modulation of the substorm current wedge by bursty bulk flows: 8 September 2002—Revisited

Author

Palin, L., primary, Opgenoorth, H. J., additional, Ågren, K., additional, Zivkovic, T., additional, Sergeev, V. A., additional, Kubyshkina, M. V., additional, Nikolaev, A., additional, Kauristie, K., additional, van de Kamp, M., additional, Amm, O., additional, Milan, S. E., additional, Imber, S. M., additional, Facskó, G., additional, Palmroth, M., additional, and Nakamura, R., additional

Published
2016
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21. Cluster observations of field aligned current at the dawn flank of a burs flow

Author

Snekvik, K., Haaland, S., Osthaard, N., Hasegawa, Hiroshi, Nakamura, R., Takada, Taku, Juusola, L., Amm, O., Pitout, F., Reme, H., Klecker, B., Lucek, E. A., 長谷川, 洋, 高田, 拓, Snekvik, K., Haaland, S., Osthaard, N., Hasegawa, Hiroshi, Nakamura, R., Takada, Taku, Juusola, L., Amm, O., Pitout, F., Reme, H., Klecker, B., Lucek, E. A., 長谷川, 洋, and 高田, 拓

Abstract

著者人数：12名

Published
2015

22. An interpretation of spacecraft and ground based observations of multiple omega band events

Author

Weygand, J. M., Kivelson, M. G., Frey, H. U., Rodriguez, J. V., Angelopoulos, V., Redmon, R., Barker-Ream, J., Grocott, A., Amm, O., Weygand, J. M., Kivelson, M. G., Frey, H. U., Rodriguez, J. V., Angelopoulos, V., Redmon, R., Barker-Ream, J., Grocott, A., and Amm, O.

Abstract

The source of the auroral phenomenon known as omega bands is not yet known. We examine in detail five different intervals when omega bands were observed on March 9th, 2008 between 0400 UT and 1100 UT over central Canada using both ground and space-based instrumentation. The THEMIS all sky imagers show the development of some of the omega bands from north-south streamers. Spherical elementary currents derived from ground magnetometer data indicate that the omega bands lie near the interface between the region 1 and region 2 currents in the post-midnight sector. THEMIS spacecraft data from the pre-midnight sector display multiple high speed flows and dipolarization features associated with high levels of geomagnetic activity, whereas four GOES geosynchronous spacecraft show multiple injections and dipolarization features. Magnetic field line tracing suggests that the magnetospheric location of the omega bands is at or just beyond geosynchronous orbit. We discuss in detail two potential source mechanisms for the omega bands: plasma sheet velocity shears and high speed flows in the magnetotail and relate the available data to those mechanisms. Our data and a magnetohydrodynamic (MHD) simulation support high speed flows in the magnetotail as the most likely generation mechanism, although the distribution of the magnetotail spacecraft does not provide unambiguous support for our interpretation of the source mechanism. (C) 2015 Elsevier Ltd. All rights reserved.

Published
2015

23. IMPALAS: Investigation of MagnetoPause Activity using Longitudinally-Aligned Satellites―-a mission concept proposed for the ESA M3 2020/2022 launch

Author

Owen, C. J., Amm, O., Bruno, R., Keyser, J. de, Dunlop, M., Eastwood, J., Fazakerley, A. N., Fontaine, D., Forsyth, C., Hellinger, P., Hercik, D., Jacquey, C., Milan, S., Raeder, J., Sibeck, D. G., Stverak, S., Travnicek, P., Walsh, A. P., Wild, J., Hasegawa, Hiroshi, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, 010504 meteorology & atmospheric sciences, Spacecraft, business.industry, Field line, Astronomy, Magnetosphere, Astronomy and Astrophysics, Magnetic reconnection, Geophysics, 01 natural sciences, Solar wind, Magnetosheath, Space and Planetary Science, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Physics::Space Physics, Magnetopause, Astrophysics::Earth and Planetary Astrophysics, Ionosphere, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

著者人数: 20名, Accepted: 2011-07-19, 資料番号: SA1003262000

Published
2012
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24. Birth and Life of Auroral Arcs Embedded in the Evening Auroral Oval

Author

Haerendel, G., Chaston, C. C., Frey, H. U., Amm, O., Juusola, L., Nakamura, R., Seran, Elena, Weygand, J. M., Max-Planck-Institut für Extraterrestrische Physik (MPE), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Finnish Meteorological Institute (FMI), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Physics::Space Physics
Abstract

International audience; We report on all-sky camera observations at Ft. Simpson during the crossing of the FAST spacecraft on 09 March 2008 at about 19:00 MLT. FAST registered eight auroral arcs with the associated upward currents and two periods of downward currents during the crossing time of five minutes. All arcs were moving equatorward with speeds near 300 m/s. Some of them exhibited local broadening and subsequent unfolding. Most remarkable was the appearance of new arcs at the poleward border of the auroral oval, clearly marked by an Alfvénic arc. The FAST data on energy and energy flux of the precipitating electrons and the jumps of the transverse magnetic perturbation field through the arcs were evaluated for five of the arcs following the formalism of Haerendel [2007]. This led to very consistent values for the integral wave impedance, field-parallel conductance, Alfvénic transit time, arc width, proper motion, and total energy release including the ionospheric dissipation. The most significant result is that all equatorward motions of the arcs were consistent with being proper motions in the rest frame of the ambient plasma. This is observational evidence for the arcs feeding on the magnetic energy liberated by the release of shear stresses in a region of dominantly upward field-aligned currents.

Published
2011

28. Simultaneous observation of substorm onset by Reimei - ground - TEMIS

Author

Sakanoi, Takeshi, Frey, H.U., Mende, S.B., Amm, O., Lanchester, B., Whiter, D., Yamazaki, Atsushi, Asamura, Kazushi, Hirahara, Masafumi, and Donovan, E.

Abstract

第10回宇宙科学シンポジウム (2010年1月7日-8日. 宇宙航空研究開発機構宇宙科学研究本部), 10th Space Science Symposium (January 7-8, 2010. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)), Sagamihara, Kanagawa Japan, 形態: カラー図版あり, 形態: CD-ROM1枚, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, 資料番号: AA0064742174

Published
2010

29. Small and meso-scale properties of a substorm onset auroral arc

Author

Frey, H. U., Amm, O., Chaston, C. C., Fu, S., Haerendel, G., Juusola, L., Karlsson, T., Lanchester, B., Nakamura, R., Ostgaard, N., Sakanoi, T., Seran, Elena, Whiter, D., Weygand, J., Asamura, K., Hirahara, M., Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Finnish Meteorological Institute (FMI), School of Earth and Space Sciences [Hefei], University of Science and Technology of China [Hefei] (USTC), Max-Planck-Institut für Extraterrestrische Physik (MPE), Department of Physics and Technology [Bergen] (UiB), University of Bergen (UiB), Department of Space and Plasma Physics [Stockholm], KTH School of Electrical Engineering, Royal Institute of Technology [Stockholm] (KTH )-Royal Institute of Technology [Stockholm] (KTH ), School of Physics and Astronomy [Southampton], University of Southampton, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Planetary Plasma and Atmospheric Research Center [Sendai] (PPARC), Tohoku University [Sendai], HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), Department of Earth and Planetary Science [Tokyo], Graduate School of Science [Tokyo], The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo), The University of Tokyo (UTokyo), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Aurora, Physics::Space Physics, Small-scale
Abstract

International audience; We present small and meso-scale properties of a substorm onset arc observed simultaneously by the Reimei and THEMIS satellites together with ground-based observations by the THEMIS GBO system. The optical observations revealed the slow equatorward motion of the growth-phase arc and the development of a much brighter onset arc poleward of it. Both arcs showed the typical particle signature of electrostatic acceleration in an inverted-V structure together with a strong Alfvén wave acceleration signature at the poleward edge of the onset arc. Two THEMIS spacecraft encountered earthward flow bursts around the times the expanding optical aurora reached their magnetic footprints in the ionosphere. The particle and field measurements allowed for the reconstruction of the field-aligned current system and the determination of plasma properties in the auroral source region. Auroral arc properties were extracted from the optical and particle measurements and were used to compare measured values to theoretical predictions of the electrodynamic model for the generation of auroral arcs. Good agreement could be reached for the meso-scale arc properties. A qualitative analysis of the internal structuring of the bright onset arc suggests the operation of the tearing instability which provides a 'rope-like' appearance due to advection of the current in the sheared flow across the arc. We also note that for the observed parameters ionospheric conductivity gradients due to electron precipitation will be unstable to the feedback instability in the ionospheric Alfvén resonator that can drive structuring in luminosity over the range of scales observed.

Published
2010
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30. Low- altitude electron acceleration due to multiple flow bursts in themagnetotail

Author

Nakamura, R., Karlsson, Tomas, Hamrin, M., Nilsson, H., Marghitu, O., Amm, O., Bunescu, C., Constantinescu, V., Frey, H. U., Keiling, A., Semeter, J., Sorbalo, E., Vogt, J., Forsyth, C., Kubyshkina, M. V., Nakamura, R., Karlsson, Tomas, Hamrin, M., Nilsson, H., Marghitu, O., Amm, O., Bunescu, C., Constantinescu, V., Frey, H. U., Keiling, A., Semeter, J., Sorbalo, E., Vogt, J., Forsyth, C., and Kubyshkina, M. V.

Abstract

At 10:00 UT on 25 February 2008, Cluster 1 spacecraft crossed the near-midnight auroral zone, at about 2R(E) altitude, while two of the Time History of Events and Macroscale Interactions During Substorms (THEMIS) spacecraft, THD and THE, observed multiple flow bursts on the near-conjugate plasma sheet field lines. The flow shear pattern at THEMIS was consistent with the vortical motion at duskside of a localized flow channel. Coinciding in time with the flow bursts, Cluster 1 observed bursts of counterstreaming electrons with mostly low energies (441eV), accompanied by short time scale (<5s) magnetic field disturbances embedded in flow-associated field-aligned current systems. This conjugate event not only confirms the idea that the plasma sheet flows are the driver of the kinetic Alfven waves accelerating the low-energy electrons but is a unique observation of disturbances in the high-altitude auroral region relevant to the multiple plasma sheet flows. Key Points First observation of multiple flow signatures on near-conjugate flux tubes Low-energy electron profile suggests Alfvenic acceleration due to fast flow Multiple flow bursts are obtained to extend over large radial distance in tail, QC 20140508

Published
2014
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31. Magnetosphere-ionosphere coupling of global Pi2 pulsations

Author

Keiling, A., Marghitu, O., Vogt, J., Amm, O., Bunescu, C., Constantinescu, V., Frey, H., Hamrin, M., Karlsson, Tomas, Nakamura, R., Nilsson, H., Semeter, J., Sorbalo, E., Keiling, A., Marghitu, O., Vogt, J., Amm, O., Bunescu, C., Constantinescu, V., Frey, H., Hamrin, M., Karlsson, Tomas, Nakamura, R., Nilsson, H., Semeter, J., and Sorbalo, E.

Abstract

Global Pi2 pulsations have mainly been associated with either low/middle latitudes or middle/high latitudes and, as a result, have been treated as two different types of Pi2 pulsations, either the plasmaspheric cavity resonance or the transient response of the substorm current wedge, respectively. However, in some reports, global Pi2 pulsations have a single period spanning low/middle/high latitudes. This super global type has not yet been satisfactorily explained. In particular, it has been a major challenge to identify the coupling between the source region and the ground. Here we report two consecutive super global Pi2 events which were observed over a wide latitudinal and longitudinal range. Using four spacecraft that were azimuthally spread out in the nightside and one spacecraft in the tail lobe, it was possible to follow the Pi2 signal along various paths with time delays from the magnetotail to the ground. Furthermore, it was found that the global pulsations were a combination of various modes including the transient Alfven and fast modes, field line resonance, and possibly a forced cavity-type resonance. As for the source of the Pi2 periodicity, oscillatory plasma flow inside the plasma sheet during flow braking (e.g., interchange oscillations) is a likely candidate. Such flow modulations, resembling the ground Pi2 pulsations, were recorded for both events., QC 20140625

Published
2014
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32. Auroral Small-and Meso-Scale Structures, Origin and Function

Author

Frey, H. U., Amm, O., Chaston, C. C., Fu, S., Haerendel, G., Juusola, L., Karlsson, R., Lanchester, B. S., Nakamura, R., Ostgaard, N., Sakanoi, T., Seran, Elena, Whiter, D., Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Finnish Meteorological Institute (FMI), Peking University [Beijing], Max-Planck-Institut, Royal Institute of Technology [Stockholm] (KTH ), University of Southampton, Austrian Academy of Sciences (OeAW), University of Bergen (UiB), Tohoku University [Sendai], HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Substorms, [SDU]Sciences of the Universe [physics], Magnetosphere/ionosphere interactions, Auroral phenomena, Energetic particles: precipitating
Abstract

International audience; Discrete auroral arcs regularly display small- and meso-scale distortions that can appear suddenly and move with speeds that are not related to plasma speeds in the ionosphere but rather represent properties of the acceleration processes in the magnetosphere. The temporal and spatial structure of each small-scale structure is thus evidence for its distinct dynamic role in the interaction between the hot magnetospheric and the cold, dense ionospheric plasmas. We analyzed passes of Reimei and FAST over the network of THEMIS Ground-Based Observatories (GBO) with all-sky cameras to combine small- and medium-scale auroral imaging with in-situ measurements of the precipitating particles in order to determine the properties and characteristics of auroral arcs and embedded small-scale structures. The THEMIS or Cluster spacecraft provided additional measurements of magnetospheric plasma and the GBO magnetometers allowed for the determination of ionospheric currents and their dynamic changes. The combination of in-situ and remotely determined auroral arc properties allowed for the complete characterization of a substorm breakup arc and embedded small-scale structures. We find consistency between theoretical expectations and observed values for arc and fold speeds and dimensions. The leading edge of the breakup arc with Alfvenic accelerated electrons exhibits the fastest fold speeds while the wider inverted-V arc shows less structure and internal speeds. Twin vortex shear flows observed by two of the THEMIS spacecraft are related to the poleward expansion of the breakup arc, the development of the substorm current wedge, and the appearance of a strong upward/downward current system. The scale size and motion of the small-scale structures signifies the dynamics of the magnetospheric plasma and the acceleration processes responsible for their generation.

Published
2009

35. Auroral streamers and magnetic flux closure

Author

Hubert, B., Kauristie, K., Amm, O., Milan, S. E., Grocott, A., Cowley, S. W. H., and Pulkkinen, T. I.

Subjects
Physics::Plasma Physics, Physics::Space Physics, Physics::Geophysics
Abstract

On 7 December 2000 at 2200 UT an auroral streamer was observed to develop above Scandinavia with the IMAGE-FUV global imagers. The ionospheric equivalent current deduced from the MIRACLE-IMAGE Scandinavian ground-based network of magnetometers is typical of a substorm-time streamer. Observations of the proton aurora using the SI12 imager onboard the IMAGE satellite are combined with measurements of the ionospheric convection obtained by the SuperDARN radar network to compute the dayside merging and nightside flux closure rates. On the basis of this and other similar events, it is found that auroral streamers appear during the period of most intense flux closure in the magnetotail, most often shortly after substorm onset. The ionospheric convection velocity, as measured by SuperDARN, appears to be reduced in the vicinity of the streamer, suggesting de-coupling of magnetospheric and ionospheric plasma flows in the region of enhanced ionospheric conductance.

Published
2007
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36. Association of Pi2 pulsations and pulsed reconnection: ground and Cluster observations in the tail lobe at 16 RE

Author

Keiling, A., Fujimoto, M., Hasegawa, H., Honary, F., Victor Sergeev, Semenov, V. S., Frey, H. U., Amm, O., Reme, H., Dandouras, I., Lucek, E., Space Sciences Laboratory [Berkeley] ( SSL ), University of California [Berkeley], Earth and Planetary Sciences, Institute of Space and Astronautical Science ( ISAS ), Department of Communication Systems, St Petersburg State University ( SPbU ), Finnish Meteorological Institute ( FMI ), Centre d'étude spatiale des rayonnements ( CESR ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Space and Atmospheric Physics Group [London], Blackett Laboratory, Imperial College London-Imperial College London, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Department of Earth and Planetary Sciences [TITECH Tokyo], Tokyo Institute of Technology [Tokyo] (TITECH), Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), St Petersburg State University (SPbU), Finnish Meteorological Institute (FMI), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), University of California-University of California, Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:Geophysics. Cosmic physics, lcsh:QC801-809, Physics::Space Physics, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Astrophysics::Solar and Stellar Astrophysics, lcsh:Q, [ SDU.STU ] Sciences of the Universe [physics]/Earth Sciences, lcsh:Science, lcsh:Physics, lcsh:QC1-999
Abstract

Accepted: 2006-11-02, 資料番号: SA1000441000

Published
2006

37. Extreme solar-terrestrial events of October 2003: High-latitude and Cluster observations of the large geomagnetic disturbances on 30 October

Author

Rosenqvist, L., Opgenoorth, H., Buchert, S., Mccrea, I., Amm, O., Lathuillere, Chantal, Swedish Institute of Space Physics [Uppsala] (IRF), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Finnish Meteorological Institute (FMI), Laboratoire de Planétologie de Grenoble (LPG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
DYNAMICS, MODEL, TAIL, WIND CONTROL, ONSETS, EARTHS MAGNETOSPHERE, INTERPLANETARY MAGNETIC-FIELD, [SDU]Sciences of the Universe [physics], CLOUDS, SUBSTORMS, STORMS
Abstract

International audience; The extremely large solar eruption on 28 October 2003 caused an intense geomagnetic storm at Earth. A second solar eruption on 29 October resulted in a reintensification of the storm about a day later. Similarities and differences between these two events in terms of solar eruption, solar wind driver, and their resulting effect on the near-Earth environment are investigated and put into context of previous works on storm geoeffectivness. Within the second storm some of the strongest substorms in the history of magnetic recordings occurred in northern Scandinavia. The aim of this study is to investigate the cause and resulting effects of these extreme geomagnetic disturbances on the ionosphere and upper atmosphere, focusing on the northern Scandinavian sector where these disturbances reached extremely high values. During this time period, well after the initial arrival of the Interplanetary Coronal Mass Ejection (ICME), the Cluster spacecraft were located at the flank of the magnetospheric tail. The satellites were passed several times by an inward and consecutively outward moving magnetopause in close relation to the substorm intensifications in northern Scandinavia. We propose that the evolution of these magnetospheric substorm intensifications are influenced by the changing dynamics of the solar wind in the form of increased pressure occurring after a prolonged period of southward Interplanetary Magnetic Field (IMF) and thus excessive energy loading into the magnetosphere prior to the onset of the intensifications. We present evidence of external pressure pulse triggering and possibly also quenching of these substorm onsets and recoveries. In addition, EISCAT data have been used to investigate the detailed local behavior of the ionospheric plasma, giving rise to such extreme disturbances. We found that in this case, extreme combinations of enhanced conductivity and intense electric field resulted in very high current intensities (westward electrojet ∼7.4 MA) and very fast onset of such currents. The inline equation associated geomagnetically induced currents caused power failures in southern Sweden.

Published
2005
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40. Substorm Current Wedge Revisited

Author

Kepko, L., primary, McPherron, R. L., additional, Amm, O., additional, Apatenkov, S., additional, Baumjohann, W., additional, Birn, J., additional, Lester, M., additional, Nakamura, R., additional, Pulkkinen, T. I., additional, and Sergeev, V., additional

Published
2014
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42. Approximate forms of daytime ionospheric conductance

Author

Ieda, A., primary, Oyama, S., additional, Vanhamäki, H., additional, Fujii, R., additional, Nakamizo, A., additional, Amm, O., additional, Hori, T., additional, Takeda, M., additional, Ueno, G., additional, Yoshikawa, A., additional, Redmon, R. J., additional, Denig, W. F., additional, Kamide, Y., additional, and Nishitani, N., additional

Published
2014
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43. Magnetosphere‐ionosphere coupling of global Pi2 pulsations

Author

Keiling, A., primary, Marghitu, O., additional, Vogt, J., additional, Amm, O., additional, Bunescu, C., additional, Constantinescu, V., additional, Frey, H., additional, Hamrin, M., additional, Karlsson, T., additional, Nakamura, R., additional, Nilsson, H., additional, Semeter, J., additional, and Sorbalo, E., additional

Published
2014
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44. Low‐altitude electron acceleration due to multiple flow bursts in the magnetotail

Author

Nakamura, R., primary, Karlsson, T., additional, Hamrin, M., additional, Nilsson, H., additional, Marghitu, O., additional, Amm, O., additional, Bunescu, C., additional, Constantinescu, V., additional, Frey, H. U., additional, Keiling, A., additional, Semeter, J., additional, Sorbalo, E., additional, Vogt, J., additional, Forsyth, C., additional, and Kubyshkina, M. V., additional

Published
2014
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47. Cluster multipoint study of the acceleration potential pattern and electrodynamics of an auroral surge and its associated horn arc

Author

Marklund, Göran T., Sadeghi, Soheil, Li, Bin, Amm, O., Cumnock, Judy A., Zhang, Y., Nilsson, H., Masson, A., Karlsson, Tomas, Lindqvist, Per-Arne, Fazakerley, A., Lucek, E., Pickett, J., Marklund, Göran T., Sadeghi, Soheil, Li, Bin, Amm, O., Cumnock, Judy A., Zhang, Y., Nilsson, H., Masson, A., Karlsson, Tomas, Lindqvist, Per-Arne, Fazakerley, A., Lucek, E., and Pickett, J.

Abstract

Cluster results are presented from the acceleration region of an auroral surge and connected horn arc, observed during an extended time period of substorm activity. The Cluster spacecraft crossed different magnetic local time (MLT) sectors of the surge and horn, with lag times of 2-10 min. Acceleration potential patterns are derived for the horn arc and for the double arc (surge and horn) at the surge front and deeper into the surge. The parallel potential drop of the horn arc ranged between 4 and 7 kV. At the surge front, two weakly coupled U-potentials with parallel potential drops of 8 (7) kV and 7 (5) kV were derived for the surge and horn, respectively, from the C3 (C4) data. A similar, more coupled pattern was derived for the region deeper into the surge. We also address how the field-aligned currents of the surge and horn system close in the ionosphere. The Cluster data allow almost simultaneous estimates of the latitudinal current closure at various MLT sectors. Significant net upward currents are derived for the horn and surge, whereas the currents at the surge front were found to be balanced. The net upward horn current is proposed to be fed by the zonal divergence of the westward Pedersen current in the horn, consistent with the acceleration potential decrease in the westward horn direction. The net upward surge current is proposed to be fed by the divergence of a westward electrojet and by localized downward currents adjacent to the surge., QC 20121126

Published
2012
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48. Comparison between SuperDARN flow vectors and equivalent ionospheric currents from ground magnetometer arrays

Author

Weygand, J. M., Amm, O., Angelopoulos, V., Milan, S. E., Grocott, A., Gleisner, H., Stolle, C., Weygand, J. M., Amm, O., Angelopoulos, V., Milan, S. E., Grocott, A., Gleisner, H., and Stolle, C.

Abstract

Equivalent ionospheric currents obtained with the spherical elementary current systems (SECS) method and derived from nearly 100 ground magnetometers spread over North America and Greenland are compared with ionospheric flow vectors measured by the SuperDARN radars during both the summer and winter seasons. This comparison is done over a range of spatial separations, magnetic latitudes, magnetic local times, and auroral electrojet activity to investigate under what conditions the vectors are anti-parallel to one another. Our results show that in general the equivalent ionospheric currents are anti-parallel to the flows and the best results are achieved within the auroral oval during active geomagnetic conditions in the dawn, dusk and noon sectors in the northern hemisphere summer. These results indicate the best anti-parallel alignment occurs when the currents and flows are large and well defined. Factors that may influence the alignment include ionospheric conductivity gradients and quiet time backgrounds. Our results can be used to approximate the macroscopic (∼1000 km) ionospheric convection patterns. The SECS maps represent a value-added product from the raw magnetometer database and can be used for contextual interpretation; they can help with our understanding of magnetosphere-ionosphere coupling mechanisms using ground arrays and the magnetospheric spacecraft data, and they can be used as input for other techniques.

Published
2012

49. Interplanetary magnetic field rotations followed from L1 to the ground:the response of the Earth's magnetosphere as seen by multi-spacecraft and ground-based observations

Author

Volwerk, M., Berchem, J., Bogdanova, Y. V., Constantinescu, O. D., Dunlop, M. W., Eastwood, J.P., Escoubet, P., Fazakerley, A. N., Frey, H., Hasegawa, H., Lavraud, B., Panov, E. V., Shen, C., Shi, J.-K., Taylor, M. G. G. T., Wang, J., Wild, James, Zhang, Q.-H., Amm, O., Weygand, J. M., Volwerk, M., Berchem, J., Bogdanova, Y. V., Constantinescu, O. D., Dunlop, M. W., Eastwood, J.P., Escoubet, P., Fazakerley, A. N., Frey, H., Hasegawa, H., Lavraud, B., Panov, E. V., Shen, C., Shi, J.-K., Taylor, M. G. G. T., Wang, J., Wild, James, Zhang, Q.-H., Amm, O., and Weygand, J. M.

Abstract

A study of the interaction of solar wind magnetic field rotations with the Earth's magnetosphere is performed. For this event there is, for the first time, a full coverage over the dayside magnetosphere with multiple (multi)spacecraft missions from dawn to dusk, combined with ground magnetometers, radar and an auroral camera, this gives a unique coverage of the response of the Earth's magnetosphere. After a long period of southward IMF Bz and high dynamic pressure of the solar wind, the Earth's magnetosphere is eroded and compressed and reacts quickly to the turning of the magnetic field. We use data from the solar wind monitors ACE and Wind and from magnetospheric missions Cluster, THEMIS, DoubleStar and Geotail to investigate the behaviour of the magnetic rotations as they move through the bow shock and magnetosheath. The response of the magnetosphere is investigated through ground magnetometers and auroral keograms. It is found that the solar wind magnetic field drapes over the magnetopause, while still co-moving with the plasma flow at the flanks. The magnetopause reacts quickly to IMF Bz changes, setting up field aligned currents, poleward moving aurorae and strong ionospheric convection. Timing of the structures between the solar wind, magnetosheath and the ground shows that the advection time of the structures, using the solar wind velocity, correlates well with the timing differences between the spacecraft. The reaction time of the magnetopause and the ionospheric current systems to changes in the magnetosheath Bz seem to be almost immediate, allowing for the advection of the structure measured by the spacecraft closest to the magnetopause.

Published
2011

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