1. Bow shock specularly reflected ions in the presence of low-frequency electromagnetic waves: a case study
- Author
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Iannis Dandouras, Jean-André Sauvaud, M. B. Bavassano-Cattaneo, Matthew D. McCarthy, L. M. Kistler, D. LeQuéau, Mark Q. Wilber, Rickard Lundin, Henri Rème, J. M. Bosqued, Jonathan Eastwood, B. Klecker, Karim Meziane, André Balogh, C. Mazelle, A. Korth, George K. Parks, Physics Department, 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 Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Space and Atmospheric Physics Group [London], Blackett Laboratory, Imperial College London-Imperial College London, Space Science Center, University of New Hamshire, Department of Earth and Space Sciences [Seattle], University of Washington [Seattle], Max-Planck-Institut für Extraterrestrische Physik (MPE), Max-Planck-Institut für Aeronomie (MPI Aeronomie), Max-Planck-Gesellschaft, Istituto di Fisica dello Spazio Interplanetario (IFSI), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Swedish Institute of Space Physics [Kiruna] (IRF), 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, University of California [Berkeley], University of California-University of California, Consiglio Nazionale delle Ricerche (CNR), 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 Sciences Laboratory [Berkeley] ( SSL ), Max-Planck-Institut für Extraterrestrische Physik ( MPE ), Max-Planck-Institut für Aeronomie ( MPI Aeronomie ), Istituto di Fisica dello Spazio Interplanetaro ( IFSI ), Istituto Nazionale di Astrofisica ( INAF ), and Swedish Institute of Space Physics [Kiruna] ( IRF )
- Subjects
[ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,Context (language use) ,01 natural sciences ,Electromagnetic radiation ,Optics ,0103 physical sciences ,Earth and Planetary Sciences (miscellaneous) ,Bow shock (aerodynamics) ,Specular reflection ,Pitch angle ,lcsh:Science ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Physics ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,Shock (fluid dynamics) ,business.industry ,lcsh:QC801-809 ,Geology ,Astronomy and Astrophysics ,[ SDU.STU ] Sciences of the Universe [physics]/Earth Sciences ,lcsh:QC1-999 ,Computational physics ,Solar wind ,lcsh:Geophysics. Cosmic physics ,Space and Planetary Science ,Physics::Space Physics ,Oblique shock ,lcsh:Q ,business ,lcsh:Physics - Abstract
An energetic ion (E≤40) event observed by the CLUSTER/CIS experiment upstream of the Earth's bow shock is studied in detail. The ion event is observed in association with quasi-monochromatic ULF MHD-like waves, which we show modulate the ion fluxes. According to three statistical bow shock position models, the Cluster spacecrafts are located at ~0.5 Re from the shock and the averaged bow shock θBn0 is about ~30°. The analysis of the three-dimensional angular distribution indicates that ions propagating roughly along the magnetic field direction are observed at the onset of the event. Later on, the angular distribution is gyrophase-bunched and the pitch-angle distribution is peaked at α0~θBn0, consistent with the specular reflection production mechanism. The analysis of the waves shows that they are left-handed in the spacecraft frame of reference (right-handed in the solar wind frame) and propagate roughly along the ambient magnetic field; we have found that they are in cyclotron-resonance with the field-aligned beam observed just upstream. Using properties of the waves and particles, we explain the observed particle flux-modulation in the context of θBn changes at the shock caused by the convected ULF waves. We have found that the high count rates coincide with particles leaving the shock when θBn angles are less than ~40°, consistent with the specular reflection hypothesis as the production mechanism of ions.
- Published
- 2004