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1. Investigation of the homogeneity of energy conversion processes at dipolarization fronts from MMS measurements

Author

S. W. Alqeeq, O. Le Contel, P. Canu, A. Retinò, T. Chust, L. Mirioni, L. Richard, Y. Aït-Si-Ahmed, A. Alexandrova, A. Chuvatin, N. Ahmadi, S. M. Baraka, R. Nakamura, F. D. Wilder, D. J. Gershman, P. A. Lindqvist, Yu. V. Khotyaintsev, R. E. Ergun, J. L. Burch, R. B. Torbert, C. T. Russell, W. Magnes, R. J. Strangeway, K. R. Bromund, H. Wei, F. Plaschke, B. J. Anderson, B. L. Giles, S. A. Fuselier, Y. Saito, B. Lavraud, Laboratoire de Physique des Plasmas (LPP), 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), Swedish Institute of Space Physics [Uppsala] (IRF), Department of Physics and Astronomy [Uppsala], Uppsala University, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], National Institute of Aerospace [Hampton] (NIA), Institut für Weltraumforschung = Space Research institute [Graz] (IWF), Osterreichische Akademie der Wissenschaften (ÖAW), University of Texas at Arlington [Arlington], NASA Goddard Space Flight Center (GSFC), Royal Institute of Technology [Stockholm] (KTH ), Southwest Research Institute [San Antonio] (SwRI), Space Science Center & Department of Physics, University of New Hampshire (UNH), Department of Earth, Planetary and Space Sciences [Los Angeles] (EPSS), University of California [Los Angeles] (UCLA), University of California (UC)-University of California (UC), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), Institut de recherche en astrophysique et planétologie (IRAP), 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), and 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)

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Condensed Matter Physics, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; We report on six dipolarization fronts (DFs) embedded in fast earthward flows detected by the Magnetospheric Multiscale mission during asubstorm event on 23 July 2017. We analyzed Ohm’s law for each event and found that ions are mostly decoupled from the magnetic field byHall fields. However, the electron pressure gradient term is also contributing to the ion decoupling and likely responsible for an electrondecoupling at DF. We also analyzed the energy conversion process and found that the energy in the spacecraft frame is transferred from theelectromagnetic field to the plasma (J E > 0) ahead or at the DF, whereas it is the opposite (J E < 0) behind the front. This reversal ismainly due to a local reversal of the cross-tail current indicating a substructure of the DF. In the fluid frame, we found that the energy ismostly transferred from the plasma to the electromagnetic field (J E0 < 0) and should contribute to the deceleration of the fast flow.However, we show that the energy conversion process is not homogeneous at the electron scales due to electric field fluctuations likely relatedto lower-hybrid drift waves. Our results suggest that the role of DF in the global energy cycle of the magnetosphere still deserves more investigation. In particular, statistical studies on DF are required to be carried out with caution due to these electron scale substructures.

Published
2022
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2. Small‐Scale Magnetic Structures: Cluster Observations

Author

Michael Gedalin, Michael A. Balikhin, P. Canu, Simon Walker, Keith H. Yearby, Department of Automatic Control and Systems Engineering [ Sheffield] (ACSE), University of Sheffield [Sheffield], Department of Automatic Control and Systems Engineering, Department of Physics [Beer-Sheva], Ben-Gurion University of the Negev (BGU), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, and 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)

Subjects
Physics, Geophysics, 010504 meteorology & atmospheric sciences, Scale (ratio), Space and Planetary Science, 0103 physical sciences, Cluster (physics), [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Statistical physics, 010303 astronomy & astrophysics, 01 natural sciences, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience

Published
2021
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3. Transport of Solar Wind H+ and He++ Ions across Earth's Bow Shock

Author

H. E. Kim, Henri Rème, George K. Parks, Yuqiang Ma, S. Y. Fu, P. Canu, M. L. Goldstein, Ying Liu, Zhongwei Yang, Ensang Lee, Iannis Dandouras, J. Hong, N. Lin, 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, Shock wave, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, 01 natural sciences, Astrobiology, Ion, Solar wind, 13. Climate action, Space and Planetary Science, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Physics::Space Physics, Bow shock (aerodynamics), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Earth (classical element), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract

International audience; We have investigated the dependence of mass, energy, and charge of solar wind (SW) transport across Earth?s bow shock. An examination of 111 crossings during quiet SW in both quasi-perpendicular and quasi-parallel shock regions shows that 64 crossings had various degrees of heating and thermalization of SW. We found 22 crossings where the SW speed was

Published
2016
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4. Experimental determination of the dispersion relation of magnetosonic waves

Author

P. Canu, Iannis Dandouras, Michael A. Balikhin, Chris Carr, Keith H. Yearby, David R. Shklyar, Simon Walker, 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), Science and Technology Facilities Council (STFC), 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, Wave propagation, Magnetosphere, Magnetic dip, Magnetosonic wave, Electron, Computational physics, symbols.namesake, Geophysics, Classical mechanics, Space and Planetary Science, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Van Allen radiation belt, Dispersion relation, Physics::Space Physics, symbols, Dispersion (water waves), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Magnetosonic waves are commonly observed in the vicinity of the terrestrial magnetic equator. It has been proposed that within this region they may interact with radiation belt electrons, accelerating some to high energies. These wave-particle interactions depend upon the characteristic properties of the wave mode. Hence, determination of the wave properties is a fundamental part of understanding these interaction processes. Using data collected during the Cluster Inner Magnetosphere Campaign, this paper identifies an occurrence of magnetosonic waves, discusses their generation and propagation properties from a theoretical perspective, and utilizes multispacecraft measurements to experimentally determine their dispersion relation. Their experimental dispersion is found to be in accordance with that based on cold plasma theory.

Published
2015
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5. What is the nature of magnetosheath FTEs?

Author

P. Canu, Philippe Louarn, Dominique Fontaine, Alain Roux, Olivier Le Contel, Patrick Robert, 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, Leading edge, Field line, Magnetic reconnection, Geophysics, Magnetic field, Computational physics, Magnetosheath, Space and Planetary Science, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Physics::Space Physics, Trailing edge, Flux transfer event, Magnetopause, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Cluster multipoint measurements are used to study two successive magnetosheath flux transfer events (FTEs). Magnetic field lines in the leading region are found to be closed magnetospheric field lines. For event 1 these field lines are wounded up by a large current structure oriented eastward and moving poleward. Conversely, the trailing region corresponds to opened magnetic field lines. For both events the leading edge of the FTEs is a tangential discontinuity separating the magnetosheath from closed field lines. In the case of event 1 magnetosheath ions are accelerated through the FTE trailing edge via a rotational discontinuity and penetrate on closed field lines through a second discontinuity. Thus, the ion jet is accelerated equatorward of the spacecraft but the backtracking of the discontinuities and the lack of dispersion show that ion acceleration occurs at less than 2 RE from Cluster. On the other hand the extrapolation forward indicates that the FTE bulge steepens as in simulations of Dorelli and Bhattacharjee). Evidence is given for the penetration of magnetosheath ions inside the core of the FTE, on closed field lines. Magnetosheath electrons are accelerated in parallel and antiparallel directions on open and on closed field lines, thus breaking the frozen-in condition. Event 2 is also split in two distinct regions but no evidence is found for accelerated bidirectional magnetosheath electrons. For event 2 the two discontinuities at the trailing region are stacked together when they are crossed by the spacecraft, suggesting that the current splitting is a reconnection signature.

Published
2015
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6. Thin Current Sheets and Associated Electron Heating in Turbulent Space Plasma

Author

Fouad Sahraoui, David Sundkvist, Antonella Greco, Alexandros Chasapis, Luca Sorriso-Valvo, P. Canu, Alessandro Retinò, Andris Vaivads, Yu. V. Khotyaintsev, 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, Turbulence, Astronomy and Astrophysics, Magnetic reconnection, Astrophysics, Plasma, Electron, Dissipation, law.invention, Computational physics, Space and Planetary Science, law, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Intermittency, Physics::Space Physics, Astrophysical plasma, Current (fluid), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Intermittent structures, such as thin current sheets, are abundant in turbulent plasmas. Numerical simulations indicate that such current sheets are important sites of energy dissipation and particle heating occurring at kinetic scales. However, direct evidence of dissipation and associated heating within current sheets is scarce. Here, we show a new statistical study of local electron heating within proton-scale current sheets by using high-resolution spacecraft data. Current sheets are detected using the Partial Variance of Increments (PVI) method which identifies regions of strong intermittency. We find that strong electron heating occurs in high PVI (>3) current sheets while no significant heating occurs in low PVI cases (5) show the strongest heating and most of the time are consistent with ongoing magnetic reconnection. This suggests that reconnection is important for electron heating and dissipation at kinetic scales in turbulent plasmas.

Published
2015
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7. Outflow and plasma acceleration in Titan's induced magnetotail: Evidence of magnetic tension forces

Author

François Leblanc, Jean-Jacques Berthelier, Andrew J. Coates, D. A. Gurnett, Niklas J. T. Edberg, Jan-Erik Wahlund, Cesar Bertucci, Norberto Romanelli, H. Waite, P. Canu, William S. Kurth, Eduard Dubinin, M. K. Dougherty, Ronan Modolo, Instituto de Astronomía y Física del Espacio [Buenos Aires] (IAFE), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad de Buenos Aires [Buenos Aires] (UBA), 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), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Swedish Institute of Space Physics [Uppsala] (IRF), 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)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Southwest Research Institute [San Antonio] (SwRI), Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), Space and Atmospheric Physics Group [London], Blackett Laboratory, Imperial College London-Imperial College London, Max-Planck-Institut für Sonnensystemforschung (MPS), and 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)

Subjects
Magnetometer, Ciencias Físicas, Electron, Ionospheric plasma is observed in Titan's wake, 7. Clean energy, law.invention, purl.org/becyt/ford/1 [https], Acceleration, symbols.namesake, law, Physics::Plasma Physics, Physics, Plasma acceleration, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Waves in plasmas, The plasma acceleration is analyzed through Walen tests, purl.org/becyt/ford/1.3 [https], Geophysics, Plasma, This acceleration can be understood in terms of magnetic tension forces, Astronomía, Space and Planetary Science, Physics::Space Physics, symbols, Astrophysics::Earth and Planetary Astrophysics, Ionosphere, Atomic physics, Titan (rocket family), Titan, CIENCIAS NATURALES Y EXACTAS
Abstract

Cassini plasma wave and particle observations are combined with magnetometer measurements to study Titan´s induced magnetic tail. In this study, we report and analyze the plasma acceleration in Titan´s induced magnetotail observed in flybys T17, T19, and T40. Radio and Plasma Wave Science observations show regions of cold plasma with electron densities between 0.1 and a few tens of electrons per cubic centimeter. The Cassini Plasma Spectrometer (CAPS)-ion mass spectrometer (IMS) measurements suggest that ionospheric plasma in this region is composed of ions with masses ranging from 15 to 17 amu and from 28 to 31 amu. From these measurements, we determine the bulk velocity of the plasma and the Alfvén velocity in Titan's tail region. Finally, a Walén test of such measurements suggest that the progressive acceleration of the ionospheric plasma shown by CAPS can be interpreted in terms of magnetic tension forces. Fil: Romanelli, Norberto Julio. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Modolo, R.. Latmos; Francia Fil: Dubinin, E.. Max Planck Institut; Alemania Fil: Berthelier, J. J.. Latmos; Francia Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Wahlund, J. E.. Swedish Institute Of Space Physics; Suecia Fil: Leblanc, F.. Latmos; Francia Fil: Canu, P.. Ecole Polytechnique; Francia Fil: Edberg, N. J. T.. Swedish Institute Of Space Physics; Suecia Fil: Waite, H.. Southwest Research Institute; Estados Unidos Fil: Kurth, W. S.. University of Iowa; Estados Unidos Fil: Gurnett, D.. University of Iowa; Estados Unidos Fil: Coates, A.. University College London; Estados Unidos Fil: Dougherty, M.. Imperial College London; Reino Unido

Published
2014
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8. CLUSTER STAFF search coils magnetometer calibration - comparisons with FGM

Author

P. Robert, N. Cornilleau-Wehrlin, R. Piberne, Y. de Conchy, C. Lacombe, V. Bouzid, B. Grison, D. Alison, P. Canu, 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)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris, Université Paris sciences et lettres (PSL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Informatique, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Physique des plasmas, Institute of Atmospheric Physics [Prague] (IAP), and Czech Academy of Sciences [Prague] (CAS)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; The main part of Cluster Spatio Temporal Analysis of Field Fluctuations (STAFF) experiment consists of triaxial search coils allowing the measurements of the three magnetic components of the waves from 0.1 Hz up to 4 kHz. Two sets of data are produced, one by a module to filter and transmit the corresponding waveform up to either 10 or 180 Hz (STAFF-SC) and the second by an onboard Spectrum Analyser (STAFF-SA) to compute the elements of the spectral matrix for five components of the waves, 3 × B and 2 × E (from EFW experiment) in the frequency range 8 Hz to 4 kHz. In order to understand the way the output signal of the search coils are calibrated, the transfer functions of the different parts of the instrument are described as well as the way to transform telemetry data into physical units, across various coordinate systems from the spinning sensors to a fixed and known frame. The instrument sensitivity is discussed. Cross-calibration inside STAFF (SC and SA) is presented. Results of cross-calibration between the STAFF search coils and the Cluster Flux Gate Magnetometer (FGM) data are discussed. It is shown that these cross-calibrations lead to an agreement between both data sets at low frequency within a 2% error. By means of statistics done over 10 yr, it is shown that the functionalities and characteristics of both instruments have not changed during this period.

Published
2013

9. Reinterpretation of Slowdown of Solar Wind Mean Velocity in Nonlinear Structures Observed Upstream of Earth's Bow Shock

Author

J. B. Cao, P. Canu, George K. Parks, Iannis Dandouras, Matthew D. McCarthy, Henri Rème, J. Shi, N. Lin, Ensang Lee, J. Hong, Ying Liu, M. L. Goldstein, S. Y. Fu, 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, Shock wave, education.field_of_study, 010504 meteorology & atmospheric sciences, Shock (fluid dynamics), Population, Astronomy and Astrophysics, Mechanics, Astrophysics, Bow shocks in astrophysics, 01 natural sciences, Solar wind, Space and Planetary Science, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Electron temperature, Mean flow, education, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Beam (structure), 0105 earth and related environmental sciences
Abstract

International audience; Two of the many features associated with nonlinear upstream structures are (1) the solar wind (SW) mean flow slows down and deviates substantially and (2) the temperature of the plasma increases in the structure. In this Letter, we show that the SW beam can be present throughout the entire upstream event maintaining a nearly constant beam velocity and temperature. The decrease of the velocity is due to the appearance of new particles moving in the opposite direction that act against the SW beam and reduce the mean velocity as computed via moments. The new population, which occupies a larger velocity space, also contributes to the second moment, increasing the temperature. The new particles include the reflected SW beam at the bow shock and another population of lower energies, accelerated nearby at the shock or at the boundary of the nonlinear structures.

Published
2013
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10. Lessons learned from WHISPER relaxation sounder in ten years of CLUSTER mission

Author

G. Lointier, J. G. Trotignon, Jean-Louis Rauch, X. Vallieres, S. Kougblénou, P. Canu, Pierrette Décréau, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire de Physique des Plasmas (LPP), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Physics, Frequency analysis, 010504 meteorology & atmospheric sciences, Magnetosphere, Plasmasphere, Plasma oscillation, Lower hybrid oscillation, 01 natural sciences, 7. Clean energy, law.invention, Magnetosheath, law, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Satellite, Plasma diagnostics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing
Abstract

International audience; The four WHISPER instruments, part of the Wave Experiment Consortium on board the multi satellite CLUSTER mission, include each a relaxation sounder aimed to measure with a good precision and reliability the frequency positions of F p , electron plasma frequency, and of F ce , electron gyro-frequency. Those quantities give access to electron density and intensity of magnetic field, key parameters defining local plasma regime. WHISPER sounder's design and realization, based on the expertise provided by successful missions operated in late seventies and eighties (GEOS, ISEE, Viking), is characterized by use of a processor devoted to on board frequency analysis via FFT. This choice makes those relaxation sounders unique of their kind, allowing in particular a complete plasma diagnostic to be made in only 1.5 s, almost one order of magnitude faster than in the past. The CLUSTER mission itself is unique, by its multi-point capability, and by its orbit, which along the mission allowed exploring a large variety of key regions of the magnetosphere. We present in this paper a few examples of WHISPER instrument behaviour and results, exploring in particular magnetosheath, polar cap, outer and inner plasmasphere. In the latter region, F p and F ce frequency values are far above the working frequency range of the instrument. This range, however, includes the lower hybrid frequency, F lh , which shows up as a clear resonance triggered by the sounder, and allows measurement of Ne whenever F p /F ce

Published
2011
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11. Alfvén : Magnetosphere -Ionosphere Connection Explorers

Author

Dhiren Kataria, J. A. Davies, J. Manninen, Laurent Lamy, Betty Lanchester, Joachim Vogt, Yu. V. Khotyaintsev, Kirsti Kauristie, Mike Hapgood, Stephen E. Milan, E. Turunen, F. Mottez, T. Chust, Alain Roux, P. Louarn, Anastasios Anastasiadis, Masatoshi Yamauchi, Octav Marghitu, Milan Maksimovic, Anasuya Aruliah, Michel Parrot, R. Pottelette, Göran Marklund, E. A. Lucek, Vincent Génot, Maria Hamrin, Laurence Rezeau, Jean-Louis Pinçon, Christopher J. Owen, F. Pitout, Roberto Bruno, Gerhard Haerendel, P. Canu, Baptiste Cecconi, Ingrid Sandahl, I. Zouganelis, Philippe Zarka, Aurélie Marchaudon, Ioannis A. Daglis, Clare E. J. Watt, C. H. Perry, S. Kemble, C. Briand, Joran Moen, M. W. Dunlop, Rickard Lundin, Jim Wild, Olga Alexandrova, Sebastien Hess, Andrew Fazakerley, Tuija Pulkkinen, P.-L. Blelly, Nikolai Østgaard, Dominique Fontaine, Arne Pedersen, Holger Nilsson, I. J. Rae, Andrew Walsh, Hannu Koskinen, Colin Forsyth, Björn Gustavsson, Matthieu Berthomier, Ingmar Sandberg, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-École polytechnique (X)-Sorbonne Universités-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Atmospheric Physics Laboratory [UCL London], Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), ONERA, Finnish Meteorological Institute (FMI), Swedish Institute of Space Physics [Kiruna] (IRF), Max-Planck-Institut für Extraterrestrische Physik (MPE), Department of Physics and Astronomy [Leicester], University of Leicester, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Université Paris-Sud - Paris 11 (UP11)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-École polytechnique (X)-Sorbonne Universités-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), 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), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Cosmic Vision, 010504 meteorology & atmospheric sciences, Magnetosphere, 01 natural sciences, 7. Clean energy, Physics::Geophysics, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], High latitude, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], Astronomy, Astronomy and Astrophysics, Plasma, Connection (mathematics), Solar wind, Space and Planetary Science, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Ionosphere, Energy source, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

The aurorae are dynamic, luminous displays that grace the night skies of Earth’s high latitude regions. The solar wind emanating from the Sun is their ultimate energy source, but the chain of plasma physical processes leading to auroral displays is complex. The special conditions at the interface between the solar wind-driven magnetosphere and the ionospheric environment at the top of Earth’s atmosphere play a central role. In this Auroral Acceleration Region (AAR) persistent electric fields directed along the magnetic field accelerate magnetospheric electrons to the high energies needed to excite luminosity when they hit the atmosphere. The “ideal magnetohydrodynamics” description of space plasmas which is useful in much of the magnetosphere cannot be used to understand the AAR. The AAR has been studied by a small number of single spacecraft missions which revealed an environment rich in wave-particle interactions, plasma turbulence, and nonlinear acceleration processes, acting on a variety of spatio-temporal scales. The pioneering 4-spacecraft Cluster magnetospheric research mission is now fortuitously visiting the AAR, but its particle instruments are too slow to allow resolve many of the key plasma physics phenomena. The Alfvén concept is designed specifically to take the next step in studying the aurora, by making the crucial high-time resolution, multi-scale measurements in the AAR, needed to address the key science questions of auroral plasma physics. The new knowledge that the mission will produce will find application in studies of the Sun, the processes that accelerate the solar wind and that produce aurora on other planets.

Published
2011
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12. Multi-spacecraft investigation of space turbulence: lessons from Cluster and input to the Cross- Scale mission

Author

Olivier Le Contel, N. Cornilleau-Wehrlin, J. L. Pinçon, P. Canu, Khurom Kiyani, Melvyn L. Goldstein, Fouad Sahraoui, Alain Roux, Thierry Dudok de Wit, Gérard Belmont, Laurence Rezeau, Patrick Robert, 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), NASA Goddard Space Flight Center (GSFC), Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre for Fusion Space and Astrophysics [Coventry] (CFSA), University of Warwick [Coventry], 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), and Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, 010504 meteorology & atmospheric sciences, Spacecraft, Scale (ratio), business.industry, Astronomy and Astrophysics, Space (mathematics), 01 natural sciences, Space and Planetary Science, Aliasing, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Physics::Space Physics, Cluster (physics), Tetrahedron, Wavenumber, Sensitivity (control systems), Aerospace engineering, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing
Abstract

International audience; Investigating space plasma turbulence from single-point measurements is known to be characterized by unavoidable ambiguities in disentangling temporal and spatial variations. Solving this problem has been one of the major goals of the Cluster mission. For that purpose multipoint measurements techniques, such as the $k$-filtering, have been developed. Such techniques combine several time series recorded simultaneously at different points in space to estimate the corresponding energy density in the wavenumber space. Here we apply the technique to both simulated and Cluster magnetometer data in the solar wind (SW) and investigate the errors and limitations that arise due to the separation of the spacecraft and the quality of the tetrahedral configuration. Specifically, we provide an estimation of the minimum and maximum scales that can be accurately measured given a specific distance between the satellites and show the importance of the geometry of the tetrahedron and the relationship of that geometry to spatial aliasing. We also present recent results on characterizing small scale SW turbulence and provide scientific arguments supporting the need of new magnetometers having better sensitivity than the existing ones. Throughout the paper we emphasize technical challenges and their solutions that can be considered for a better preparation of the Cross- Scale mission.

Published
2011
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13. Observation and theoretical modeling of electron scale solar wind turbulence

Author

P. Canu, Fouad Sahraoui, Melvyn L. Goldstein, K. Abdul-Kader, Patrick Robert, Gérard Belmont, Laurence Rezeau, 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)-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)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, 010504 meteorology & atmospheric sciences, Turbulence, General Engineering, Energy Engineering and Power Technology, K-omega turbulence model, Astrophysics, Dissipation, Kinetic energy, 7. Clean energy, 01 natural sciences, Power law, Computational physics, Solar wind, Cascade, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Physics::Space Physics, Magnetohydrodynamics, 010306 general physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 0105 earth and related environmental sciences
Abstract

Turbulence at MagnetoHydroDynamics (MHD) scales in the solar wind has been studied for more than three decades, using data analysis, theoretical and numerical modeling. However, smaller scales have not been explored until very recently. Here, we review recent results on the first observation of cascade and dissipation of the solar wind turbulence at the electron scales. Thanks to the high resolution magnetic and electric field data of the Cluster spacecraft, we computed the spectra of turbulence up to ∼ 100 Hz (in the spacecraft reference frame) and found evidence of energy dissipation around the Doppler-shifted electron gyroscale f ρ e . Before its dissipation, the energy is shown to undergo two cascades: a Kolmogorov-like cascade with a scaling f − 1.6 above the proton gyroscale, and a new f − 2.3 cascade at the sub-proton and electron gyroscales. Above f ρ e the spectrum has a steeper power law ∼ f − 4.1 down to the noise level of the instrument. Solving numerically the linear Maxwell–Vlasov equations combined with recent theoretical predictions of the Gyro-Kinetic theory, we show that the present results are consistent with a scenario of a quasi-two-dimensional cascade into Kinetic Alfven modes (KAW). New analyses of other data sets, where the Cluster separation (of about ∼ 200 km ) allowed us to explore the sub-proton scales using the k-filtering technique, and to confirm the 2D nature of the turbulence at those scales.

Published
2011
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14. Wave emissions at half electron gyroharmonics in the equatorial plasmasphere region: CLUSTER observations and statistics

Author

F. El-Lemdani Mazouz, Pierrette Décréau, P. Canu, Xavier Vallières, Jean-Louis Rauch, Jean-Gabriel Trotignon, X. Suraud, Fabien Darrouzet, Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-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
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Aerospace Engineering, Magnetosphere, Plasmasphere, Astrophysics, 01 natural sciences, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Pitch angle, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Spectral signature, Scattering, Astronomy and Astrophysics, Geophysics, Amplitude, Earth's magnetic field, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Harmonic, General Earth and Planetary Sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Intense (n 1/2) fce emissions are a common phenomenon observed in the terrestrial inner magnetosphere. One of their interests is their possible effect in the pitch angle scattering of plasmasheet keV-electron, leading to diffuse auroras. In this paper, we present CLUSTER’s point of view about this topic, in the equatorial region of the plasmasphere, via a statistical study using 3 years of data. Spectral characteristics of these waves, which represent an important clue concerning their generation mechanism, are obtained using WHISPER data near perigee. Details on the wave spectral signature are shown in an event study, in particular their splitting in fine frequency bands. The orbit configuration of the four spacecraft offers a complete sampling on all MLT sectors. A higher occurrence rate of the emissions in the dawn sector and their confinement to the geomagnetic equator, pointed out in previous studies, are confirmed and described with additional details. The proximity of emission sites, both to the plasmapause layer and to the geomagnetic equator surface, seems to be of great importance in the behaviour of the (n 1/2) fce wave characteristics. Our study indicates for the first time, that both the intensity of (n 1/2) fce emissions, and the number of harmonic bands they cover, are increasing as the observation point is located further away outside from the plasmapause layer. Moreover, a study of the wave intensity in the first harmonic band (near 3/2 fce) shows higher amplitude for these emissions than previous published values, these emissions can play a role in the scattering of hot electrons. Finally, geomagnetic activity influence, studied via time series of the Dst index preceding observations, indicates that (n 1/2) fce emission events are observed at CLUSTER position under moderate geomagnetic activity conditions, no specific Dst time variation being required.

Published
2009
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15. CLUSTER observations of electron outflowing beams carrying downward currents above the polar cap by northward IMF

Author

Andrew Fazakerley, Romain Maggiolo, Jean-André Sauvaud, Dominique Fontaine, A. Teste, P. Canu, Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), 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), Université Fédérale Toulouse Midi-Pyrénées, Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), 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), and 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)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Field line, Astrophysics::High Energy Astrophysical Phenomena, Magnetosphere, Astrophysics, Electron, 01 natural sciences, Earth radius, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Interplanetary magnetic field, lcsh:Science, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Geology, Astronomy and Astrophysics, Geophysics, Plasma, lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Polar, lcsh:Q, Ionosphere, lcsh:Physics
Abstract

Above the polar cap, at about 5–9 Earth radii (RE) altitude, the PEACE experiment onboard CLUSTER detected, for the first time, electron beams outflowing from the ionosphere with large and variable energy fluxes, well collimated along the magnetic field lines. All these events occurred during periods of northward or weak interplanetary magnetic field (IMF). These outflowing beams were generally detected below 100 eV and typically between 40 and 70 eV, just above the photoelectron level. Their energy gain can be explained by the presence of a field-aligned potential drop below the spacecraft, as in the auroral zone. The careful analysis of the beams distribution function indicates that they were not only accelerated but also heated. The parallel heating is estimated to about 2 to 20 eV and it globally tends to increase with the acceleration energy. Moreover, WHISPER observed broadband electrostatic emissions around a few kHz correlated with the outflowing electron beams, which suggests beam-plasma interactions capable of triggering plasma instabilities. In presence of simultaneous very weak ion fluxes, the outflowing electron beams are the main carriers of downward field-aligned currents estimated to about 10 nA/m2. These electron beams are actually not isolated but surrounded by wider structures of ion outflows. All along its polar cap crossings, Cluster observed successive electron and ion outflows. This implies that the polar ionosphere represents a significant source of cold plasma for the magnetosphere during northward or weak IMF conditions. The successive ion and electron outflows finally result in a filamented current system of opposite polarities which connects the polar ionosphere to distant regions of the magnetosphere.

Published
2007
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16. A quantitative test of Jones NTC beaming theory using CLUSTER constellation

Author

Fabien Darrouzet, S. Grimald, C. C. Harvey, P. Canu, X. Suraud, Xavier Vallières, Pierrette Décréau, Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Centre d'étude spatiale des rayonnements (CESR), 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), Université Fédérale Toulouse Midi-Pyrénées, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), 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), and 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)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Magnetosphere, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Auroral kilometric radiation, Astrophysics, 01 natural sciences, 03 medical and health sciences, Position (vector), Earth and Planetary Sciences (miscellaneous), Ligand cone angle, lcsh:Science, 030304 developmental biology, 0105 earth and related environmental sciences, Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 0303 health sciences, Radio window, lcsh:QC801-809, Ecliptic, Triangulation (social science), Geology, Astronomy and Astrophysics, lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, Space and Planetary Science, lcsh:Q, lcsh:Physics, Radio wave
Abstract

Non-thermal continuum (NTC) radiation is, with auroral kilometric radiation (AKR), one of the two electromagnetic emissions generated within the Earth's magnetosphere and radiated into space. The location of the source of NTC has been sought for several decades, with only limited success. The constellation formed by the four CLUSTER spacecraft provides the possibility of triangulation in the vicinity of the source, thus allowing progress in source localisation, while simultaneously revealing the beaming properties of NTC radio sources. We present a case event showing two beams localised on opposite sides of the magnetic equator. At any selected frequency, triangulation points to a single region source of small size. Its position is compatible with the range of possible loci of sources predicted by the radio window theory of Jones (1982) in a frame of constraints relaxed from the simple sketch proposed in early works. The analysis of similar observations from the Dynamics Explorer 1 by Jones et al. (1987) enabled the authors to claim validation of the radio window theory. CLUSTER observations, however, reveal a large beaming cone angle projected onto the ecliptic plane, a feature unobservable by Dynamics Explorer which had a different spin axis orientation. According to the radio window theory, such a large observed cone angle can only be formed by a series of point sources, each beaming in a narrow cone angle. This study demonstrates the difficulty of validating NTC linear generation mechanisms using global beaming properties alone.

Published
2007
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17. Far plasma wake of Titan from the RPWS observations: A case study

Author

Rolf Boström, Gethyn R. Lewis, D. A. Gurnett, William S. Kurth, Ronan Modolo, P. Canu, Jan-Erik Wahlund, Andrew J. Coates, Swedish Institute of Space Physics [Uppsala] (IRF), Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy, University of Iowa, University of Iowa [Iowa City], Mullard Space Science Laboratory (MSSL), and University College of London [London] (UCL)

Subjects
010504 meteorology & atmospheric sciences, magnetosphere/ionosphere interaction, Magnetosphere, Electron, Astrophysics, Wake, 01 natural sciences, 7. Clean energy, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], symbols.namesake, 0103 physical sciences, Langmuir probe, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, magnetosphere interaction with satellites and rings, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Waves in plasmas, instruments and techniques, Geophysics, Plasma, 13. Climate action, symbols, General Earth and Planetary Sciences, Ionosphere, Titan (rocket family), Titan
Abstract

The Titan's plasma wake has been investigated using observations from the Radio and Plasma Wave Science (RPWS) instrument onboard the Cassini spacecraft during one Titan flyby on December 26, 2005. The Langmuir Probe and the wideband receiver suggest a strong asymmetry of the plasma wake, which is displaced from the ideal wake. Two distinct structures are identified inbound and outbound of the flyby with significantly different electron number densities (ne). The maximum electron number density reached 14 cm−3 on the Saturn side, connected to the sunlit ionosphere, while on the opposite side of Saturn observations indicate a density smaller than 2 cm−3. Other derived parameters of the Langmuir probe analysis suggest also a difference in plasma composition between the two structures, where heavy and light ions dominate the Saturn and anti-Saturn side respectively. The total ion outflow is estimated at 2–7 × 1025 ions/s assuming a cylindrical geometry for the plasma wake.

Published
2007
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18. Density holes in the upstream solar wind

Author

Ensang Lee, George K. Parks, Nicole Cornilleau-Wehrlin, J. Cao, P. Décréau, F. S. Mozer, Philippe Escoubet, H. Rème, Iannis Dandouras, M. L. Goldstein, N. Lin, M. Wilber, P. Canu, E. A. Lucek, Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Blackett Laboratory, Imperial College London, Centre d'étude spatiale des rayonnements (CESR), 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), Université Fédérale Toulouse Midi-Pyrénées, State Key Laboratory for Space Weather [Beijing] (SKSW), National Space Science Center [Beijing] (NSSC), Chinese Academy of Sciences [Beijing] (CAS)-Chinese Academy of Sciences [Beijing] (CAS), Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Space Flight Center (GSFC), European Space Agency (ESA), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), 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), State Key Laboratory of Space Weather [Beijing] (SKSW), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), and Agence Spatiale Européenne = European Space Agency (ESA)

Subjects
Physics, 010504 meteorology & atmospheric sciences, Shock (fluid dynamics), Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Coronal hole, Bow shocks in astrophysics, 01 natural sciences, Molecular physics, symbols.namesake, Solar wind, Mach number, [SDU]Sciences of the Universe [physics], 0103 physical sciences, Physics::Space Physics, symbols, Magnetopause, Particle, Astrophysical plasma, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

International audience; Larmor size transient structures with depletions as large as 99% of ambient solar wind density levels occur commonly upstream of Earth’s collisionless bow shock. These “density holes” have a mean duration of ∼17.9 ± 10.4s but holes as short as 4s have been observed. The average fractional density depletion (δn/n) inside the holes is ∼0.68 ± 0.14. The density of the upstream edge moving in the sunward direction can be enhanced by five or more times the solar wind density. Particle distributions show the steepened edge can behave like a shock, and measured local field geometries and Mach number support this view. Similarly shaped magnetic holes accompany the density holes indicating strong coupling between fields and particles. The density holes are only observed with upstream particles, suggesting that back‐streaming particles interacting with the solar wind are important.

Published
2007
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19. Narrowband Z-mode emissions interior to Saturn's plasma torus

Author

P. Canu, Michael D. Desch, William M. Farrell, M. L. Kaiser, D. A. Gurnett, William S. Kurth, NASA Goddard Space Flight Center (GSFC), Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Centre d'étude des environnements terrestre et planétaires (CETP), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Soil Science, Magnetosphere, Astrophysics, Aquatic Science, Oceanography, Plasma oscillation, 01 natural sciences, Electromagnetic radiation, plasma waves, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], 03 medical and health sciences, Narrowband, Geochemistry and Petrology, Saturn, Earth and Planetary Sciences (miscellaneous), 030304 developmental biology, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Physics, 0303 health sciences, Ecology, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Waves in plasmas, Paleontology, Forestry, Torus, Plasma, Geophysics, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Cassini
Abstract

[1] During Cassini's close approach to Saturn, on 1 July 2004, a set of narrow bandwidth plasma emissions were detected by the Radio and Plasma Wave Science (RPWS) instrument in the inner magnetosphere. These discrete tones were detected between 3 and 70 kHz, with individual tone bandwidths as low as a few hundred Hertz. The tones persisted for long times (∼1 hour) as Cassini flew in planetocentric radial distances of less than 2.5 Rs. During this time at lower radial distances, the spacecraft passed inside the inner edge of a clear and distinct plasma torus; this torus is located between 2.2 and ∼10 Rs. We describe the emissions, and demonstrate that the mode of propagation is the Z-mode. The emissions are found to originate at locations where electron plasma oscillations along the plasma torus edge are relatively intense. We describe a mechanism for fp electrostatic-to-electromagnetic wave conversion to explain the origin of the narrowband Z-mode tones. The tones allow remote-sensing of the plasma torus and indicate that the torus is dynamic, with changes in density in the tens of percent over the course of an hour.

Published
2005
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20. Whistlers observed by the Cluster spacecraft outside the plasmasphere

Author

P. Canu, M. Platino, Umran S. Inan, T. F. Bell, Pierrette Décréau, D. A. Gurnett, Jolene S. Pickett, Space, Telecommunications, and Radioscience Laboratory (STAR Lab), Stanford University, Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), and National Aeronautics and Space Administration ( grant NAG5-9974) atthe University of Iowa, and with subcontract 4000061641 to StanfordUniversity.

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Whistler, Soil Science, Plasmasphere, Aquatic Science, Oceanography, 01 natural sciences, Latitude, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), 010306 general physics, Dispersion (water waves), 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Physics, Ecology, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Relaxation (NMR), Paleontology, Forestry, Plasma, Geophysics, Lightning, Computational physics, Space and Planetary Science, Ionosphere
Abstract

International audience; Lightning generated whistlers are ubiquitous within the plasmasphere at both highand low altitudes, and these waves propagate efficiently in both ducted and nonductedmodes. On the other hand, in the magnetospheric region outside the plasmasphere,lightning-generated whistlers are commonly observed at low altitudes (up to 6000 km)but only rarely at higher altitudes near the magnetic equatorial plane. The reasons forthe lack of these waves at higher altitudes are not well understood. In the presentpaper we use data from the Wide Band Plasma (WBD) instruments on the four Clusterspacecraft to study the characteristics of lightning-generated whistlers observed on 4 separatedays in 2001 at L shells ranging from L =4toL = 5, magnetic latitudes ranging from20 to 10, and Kp indices ranging from 3 to 6. The propagation paths of thelightning-generated whistlers are determined using a two-dimensional ray-tracing modelto calculate the ray paths and group delays from the lower ionosphere to each of thefour Cluster spacecraft over a range of frequencies (1 kHz < f < 8 kHz). The electrondensity distributions used for the ray-tracing calculations are derived frommeasurements with the Whisper relaxation sounder instrument. Our new resultsindicate that whistlers are observed outside the plasmasphere in the low-density regionsonly in the presence of large-scale irregularities within which the waves are ‘‘ducted.’’This conclusion is sustained by an exhaustive search of whistlers outside theplasmasphere using all the Cluster passes during 2001 and 2002. In all the cases wefound that dispersion characteristics are matched by ray-tracing simulations only if thewhistlers are ducted. In some cases, whistler wave energy injected by an individuallightning discharge appears with significant smearing in time. The new resultspresented in this paper support a possible explanation of why whistlers outside theplasmasphere are rarely observed, based on wave conversion electromagnetic whistlermode to quasi-electrostatic lower hybrid mode (Bell et al., 2004).

Published
2005
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21. The inner magnetosphere of Saturn: Cassini RPWS cold plasmaresults from the first encounter

Author

Michiko Morooka, Reine Gill, P. Canu, Michael D. Desch, Mats André, D. A. Gurnett, George Hospodarsky, Anders Eriksson, Arne Pedersen, William S. Kurth, Jan-Erik Wahlund, Rolf Boström, T. F. Averkamp, A. M. Persoon, Georg Gustafsson, Swedish Institute of Space Physics [Uppsala] (IRF), Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physics [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), NASA Goddard Space Flight Center (GSFC), Swedish National Space Board (SNSB), and Swedish National Space Board

Subjects
Physics, Dusty plasma, 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Waves in plasmas, Astronomy, Magnetosphere, Plasma, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], symbols.namesake, Geophysics, Gas torus, 13. Climate action, Physics::Plasma Physics, Saturn, Magnetosphere of Saturn, 0103 physical sciences, Physics::Space Physics, symbols, General Earth and Planetary Sciences, Langmuir probe, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

International audience; We present new results from the inner magnetosphere of Saturn obtained by the Radio and Plasma Wave Science (RPWS) investigation onboard Cassini around the period of the Saturn orbit injection (July 1, 2004). Plasma wave electric field emissions, voltage sweeps by the Langmuir probe (LP) and radio sounder data were used to infer the cold plasma (

Published
2005
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22. Correction to ‘‘ULF wave identification in the magnetosheath: The k-filtering technique applied to Cluster II data’’

Author

P. Canu, Patrick Robert, Gérard Chanteur, L. Mellul, Nicole Cornilleau-Wehrlin, Fouad Sahraoui, Laurence Rezeau, Jean-Louis Pinçon, J. M. Bosqued, G. Belmont, André Balogh, Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), 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), Space and Atmospheric Physics Group [London], Blackett Laboratory, Imperial College London-Imperial College London, 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
Atmospheric Science, 010504 meteorology & atmospheric sciences, High Energy Physics::Lattice, Soil Science, Aquatic Science, Oceanography, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Transformation matrix, Magnetosheath, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Cluster (physics), 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Physics, Ecology, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Frame (networking), Paleontology, Forestry, Geophysics, Identification (information), Space and Planetary Science, Algorithm
Abstract

There is an error in the matrix transformation from the GSE frame to the MFA (Magnetic Field-Aligned) one

Published
2004
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23. Early results from the Whisper instrument on Cluster: an overview

Author

P. M. E. Décréau, P. Fergeau, V. Krasnoselskikh, E. Le Guirriec, M. Lévêque, Ph. Martin, O. Randriamboarison, J. L. Rauch, F. X. Sené, H. C. Séran, J. G. Trotignon, P. Canu, N. Cornilleau, H. de Féraudy, H. Alleyne, K. Yearby, P. B. Mögensen, G. Gustafsson, M. André, D. C. Gurnett, F. Darrouzet, J. Lemaire, C. C. Harvey, P. Travnicek, Whisper experimenters (Table 1), Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Sheffield [Sheffield], DSRI, I. R. F. U., University of Iowa [Iowa City], Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Centre d'étude spatiale des rayonnements (CESR), 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), Université Fédérale Toulouse Midi-Pyrénées, Czech Academy of Sciences [Prague] (CAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), 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), and 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)

Subjects
Atmospheric Science, Electron density, Drift velocity, 010504 meteorology & atmospheric sciences, Frequency band, Magnetosphere, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Plasma oscillation, 01 natural sciences, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), lcsh:Science, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Spacecraft, business.industry, lcsh:QC801-809, Geology, Astronomy and Astrophysics, Space physics, lcsh:QC1-999, Depth sounding, lcsh:Geophysics. Cosmic physics, Space and Planetary Science, lcsh:Q, business, lcsh:Physics
Abstract

The Whisper instrument yields two data sets: (i) the electron density determined via the relaxation sounder, and (ii) the spectrum of natural plasma emissions in the frequency band 2–80 kHz. Both data sets allow for the three-dimensional exploration of the magnetosphere by the Cluster mission. The total electron density can be derived unambiguously by the sounder in most magnetospheric regions, provided it is in the range of 0.25 to 80 cm-3 . The natural emissions already observed by earlier spacecraft are fairly well measured by the Whisper instrument, thanks to the digital technology which largely overcomes the limited telemetry allocation. The natural emissions are usually related to the plasma frequency, as identified by the sounder, and the combination of an active sounding operation and a passive survey operation provides a time resolution for the total density determination of 2.2 s in normal telemetry mode and 0.3 s in burst mode telemetry, respectively. Recorded on board the four spacecraft, the Whisper density data set forms a reference for other techniques measuring the electron population. We give examples of Whisper density data used to derive the vector gradient, and estimate the drift velocity of density structures. Wave observations are also of crucial interest for studying small-scale structures, as demonstrated in an example in the fore-shock region. Early results from the Whisper instrument are very encouraging, and demonstrate that the four-point Cluster measurements indeed bring a unique and completely novel view of the regions explored.Key words. Space plasma physics (instruments and techniques; discontinuities, general or miscellaneous)

Published
2001
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24. Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

Author

Jean-Louis Rauch, P. Fergeau, Keith H. Yearby, Ph. Martin, H. C. Seran, M. Lévêque, Jean-Gabriel Trotignon, P. Canu, H. Alleyne, E. Le Guirriec, Pierrette Décréau, F. X. Sené, Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Sheffield [Sheffield], and EGU, Publication

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Magnetosphere, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Plasmasphere, Plasma oscillation, 01 natural sciences, Spectral line, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), lcsh:Science, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Resonance, Geology, Astronomy and Astrophysics, Plasma, lcsh:QC1-999, Computational physics, lcsh:Geophysics. Cosmic physics, Distribution function, Space and Planetary Science, Physics::Space Physics, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, Electron temperature, lcsh:Q, lcsh:Physics
Abstract

We use the data collected by the Whisper instrument onboard the Cluster spacecraft for a first test of its capabilities in the identification of the natural plasma waves observed in the Earth’s magnetosphere. The main signatures observed at the plasma frequency, upper hybrid frequency, and electron Bernstein modes were often difficult to be reliably recognized on previous missions. We use here the characteristic frequencies provided by the resonances triggered by the relaxation sounder of Whisper to identify with good confidence the various signatures detected in the complex wave spectra collected close to the plasmapause. Coupled with the good sensitivity, frequency and time resolution of Whisper, the resonances detected by the sounder allow one to precisely spot these natural emissions. This first analysis seems to confirm the interpretation of Geos observations: the natural emissions observed in Bernstein modes above the plasma frequency, now widely observed onboard Cluster, are not modeled by a single Maxwellian electrons distribution function. Therefore, multi-temperature electron distribution functions should be considered.Key words. Space plasma physics (active perturbation experiments; waves and instabilities; instrument and techniques)

Published
2001

25. How to determine the thermal electron density and the magnetic field strength from the Cluster/Whisper observations around the Earth

Author

E. Le Guirriec, Pierrette Décréau, Ph. Martin, H. C. Seran, P. Canu, F. X. Sené, Jean-Louis Rauch, Keith H. Yearby, Orélien Randriamboarison, H. Alleyne, P. Fergeau, M. Lévêque, Vladimir Krasnoselskikh, Jean-Gabriel Trotignon, EGU, Publication, Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Automatic Control and Systems Engineering [ Sheffield] (ACSE), and University of Sheffield [Sheffield]

Subjects
Atmospheric Science, Electron density, 010504 meteorology & atmospheric sciences, Population, Magnetosphere, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 01 natural sciences, Optics, Electric field, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), education, lcsh:Science, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, education.field_of_study, business.industry, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Geology, Astronomy and Astrophysics, Space physics, Plasma, lcsh:QC1-999, Magnetic field, Computational physics, lcsh:Geophysics. Cosmic physics, Distribution function, Space and Planetary Science, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, lcsh:Q, business, lcsh:Physics
Abstract

The Wave Experiment Consortium, WEC, is a highly integrated package of five instruments used to study the plasma environment around the Earth. One of these instruments, the Waves of HIgh frequency and Sounder for Probing of Electron density by Relaxation, Whisper, aims at the thermal electron density evaluation and natural wave monitoring in the 4–83 kHz frequency range. In its active working mode, which is our primarily concern here, the Whisper instrument transmits a short wave train at a swept frequency and receives echoes after a delay. Incidentally, it behaves like a classical ground-based ionosonde. Natural modes of oscillations may thus be excited in the surrounding medium. This means that with suitable interpretations, the Whisper sounding technique becomes a powerful tool for plasma diagnosis. By taking into account the characteristic frequencies of the magnetoplasmas encountered by the Cluster spacecraft, it is indeed possible to reliably and accurately determine the electron density and, to a lesser degree, the magnetic field strength from the Whisper electric field measurements. Due to the predominantly electrostatic nature of the waves that are excited, observations of resonances may also lead to information on the electron velocity distribution functions. The existence of a hot population may indeed be revealed and the hot to cold density ratio can be estimated.Key words. Magnetospheric physics (plasma waves and instabilities). Space plasma physics (active perturbation experiments; instruments and techniques)

Published
2001

26. ULF waves in the Io torus: ULYSSES observations

Author

Naiguo Lin, Robert J. MacDowall, André Balogh, Paul J. Kellogg, P. Canu, Nicole Cornilleau-Wehrlin, C. de Villedary, R. J. Forsyth, Y. Mei, Laurence Rezeau, University of Minnesota [Twin Cities] (UMN), University of Minnesota System, School of Physics and Astronomy [Minneapolis], University of Minnesota System-University of Minnesota System, NASA Goddard Space Flight Center (GSFC), Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Blackett Laboratory, and Imperial College London

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Whistler, Equator, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics, ULYSSES MISSION, Oceanography, 01 natural sciences, TORUSES, WAVE DISPERSION, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Dispersion relation, Earth and Planetary Sciences (miscellaneous), MATHEMATICAL MODELS, 010303 astronomy & astrophysics, Water Science and Technology, Physics, Ecology, ENERGETIC PARTICLES, Forestry, Polarization (waves), Geophysics, ASTRONOMICAL MODELS, Poynting vector, Physics::Space Physics, POLARIZATION (WAVES), EXTREMELY LOW FREQUENCIES, TOROIDAL PLASMAS, Radio wave, SPACEBORNE ASTRONOMY, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Soil Science, Aquatic Science, Electromagnetic radiation, SPACE PLASMAS, Geochemistry and Petrology, ION SCATTERING, 0103 physical sciences, Pitch angle, WHISTLERS, RADIO WAVES, 0105 earth and related environmental sciences, Earth-Surface Processes, Paleontology, ION CYCLOTRON RADIATION, IO, Computational physics, 13. Climate action, Space and Planetary Science
Abstract

International audience; Throughout the Io torus, Ulysses has observed intense ultralow frequency (ULF) wave activity in both electric and magnetic components. Such ULF waves have been previously suggested as the source of ion precipitation leading to Jovian aurorae. The peaks of the wave spectra are closely related to the ion cyclotron frequencies, which is evidence of the waves being ion cyclotron waves (ICWs). Analysis of the dispersion relation using a multicomponent density model shows that at high latitudes (approximately 30 deg), peak frequencies of the waves fall into L mode branches of guided or unguided ICWs. Near the equator, in addition to the ICWs below fcO(2+), there are strong signals at approximately 10 Hz which require an unexpectedly large energetic ion temperature anistropy to be explained by the excitation of either convective or nonconvective ion cyclotron instabilities. Their generation mechanism remains open for the future study. Evaluation of the Poynting vector and the dispersion relation analysis suggest that the waves near the equator had a small wave angle relative to the magnetic field, while those observed at high latitudes were more oblique. The polarization of the waves below fcH(+) is more random than that of the whistler mode waves, but left-hand-polarized components of the waves can still be seen. The intensity of the ICWs both near the equator and at high latitudes are strong enough to meet the requirement for producing strong pitch angle scattering of energetic ions.

Published
1993
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