Observations of energetic particle escape at the magnetopause: Early results from the MMS Energetic Ion Spectrometer (EIS)

I. J Cohen; A. N Jaynes; B. H Mauk; D. N Baker; B. J Anderson; J. H Westlake; D. G Sibeck; B. L Giles; C. J Pollock; D. L Turner; J. F Fennell; J. B Blake; J. H Clemmons; J. V Craft; H. E Spence; J. T Niehof; G. D Reeves; R. B Torbert; C. T Russell; R. J Strangeway; W Magnes; K. J Trattner; S. A Fuselier; J. L Burch

doi:10.1002/2016GL068689

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Observations of energetic particle escape at the magnetopause: Early results from the MMS Energetic Ion Spectrometer (EIS)

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Observations of energetic particle escape at the magnetopause: Early results from the MMS Energetic Ion Spectrometer (EIS)

I. J Cohen, A. N Jaynes, B. H Mauk, D. N Baker, B. J Anderson, J. H Westlake, D. G Sibeck, B. L Giles, C. J Pollock, D. L Turner, …

Geophysical research letters, Vol.43(12), pp.5960-5968

06/28/2016

DOI: 10.1002/2016GL068689

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Abstract

Energetic (greater than tens of keV) magnetospheric particle escape into the magnetosheath occurs commonly, irrespective of conditions that engender reconnection and boundary‐normal magnetic fields. A signature observed by the Magnetospheric Multiscale (MMS) mission, simultaneous monohemispheric streaming of multiple species (electrons, H+, Hen+), is reported here as unexpectedly common in the dayside, dusk quadrant of the magnetosheath even though that region is thought to be drift‐shadowed from energetic electrons. This signature is sometimes part of a pitch angle distribution evolving from symmetric in the magnetosphere, to asymmetric approaching the magnetopause, to monohemispheric streaming in the magnetosheath. While monohemispheric streaming in the magnetosheath may be possible without a boundary‐normal magnetic field, the additional pitch angle depletion, particularly of electrons, on the magnetospheric side requires one. Observations of this signature in the dayside dusk sector imply that the static picture of magnetospheric drift‐shadowing is inappropriate for energetic particle dynamics in the outer magnetosphere. Key Points MMS/EIS observations afford new opportunities to study energetic (greater than tens of keV) particle interactions and escape across the magnetopause Early MMS/EIS observations reveal a new signature requiring boundary‐normal magnetic fields at the dayside dusk magnetopause MMS/EIS observes simultaneous streaming of both electrons and light ion species, previously unexpected due to magnetic drift‐shadowing

energetic particle escape

magnetic reconnection

magnetopause

magnetosheath

MMS

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Title: Subtitle: Observations of energetic particle escape at the magnetopause: Early results from the MMS Energetic Ion Spectrometer (EIS)
Creators: I. J Cohen - Johns Hopkins University Applied Physics Laboratory
A. N Jaynes - University of Colorado Boulder
B. H Mauk - Johns Hopkins University Applied Physics Laboratory
D. N Baker - University of Colorado Boulder
B. J Anderson - Johns Hopkins University Applied Physics Laboratory
J. H Westlake - Johns Hopkins University Applied Physics Laboratory
D. G Sibeck - Goddard Space Flight Center
B. L Giles - Goddard Space Flight Center
C. J Pollock - Goddard Space Flight Center
D. L Turner - The Aerospace Corporation
J. F Fennell - The Aerospace Corporation
J. B Blake - The Aerospace Corporation
J. H Clemmons - The Aerospace Corporation
J. V Craft - University of Colorado Boulder
H. E Spence - University of New Hampshire
J. T Niehof - University of New Hampshire
G. D Reeves - Los Alamos National Laboratory
R. B Torbert - University of New Hampshire
C. T Russell - University of California, Los Angeles
R. J Strangeway - University of California, Los Angeles
W Magnes - Austrian Academy of Sciences
K. J Trattner - University of Colorado Boulder
S. A Fuselier - Southwest Research Institute
J. L Burch - Southwest Research Institute
Resource Type: Journal article
Publication Details: Geophysical research letters, Vol.43(12), pp.5960-5968
DOI: 10.1002/2016GL068689
ISSN: 0094-8276
eISSN: 1944-8007
Number of pages: 9
Grant note: NASA (NNG04EB99C)
Language: English
Date published: 06/28/2016
Academic Unit: Physics and Astronomy; University College Courses
Record Identifier: 9984199841302771

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