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Observations of Energetic Particle Escape at the Magnetopause: Early Results from the MMS Energetic Ion Spectrometer (EIS)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.
Document ID
20170003188
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Cohen, I. J. (Johns Hopkins Univ. Laurel, MD, United States)
Mauk, B. H. (Johns Hopkins Univ. Laurel, MD, United States)
Anderson, B. J. (Johns Hopkins Univ. Laurel, MD, United States)
Westlake, J. H. (Johns Hopkins Univ. Laurel, MD, United States)
Sibeck, David Gary (NASA Goddard Space Flight Center Greenbelt, MD United States)
Giles, Barbara L. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Pollock, C. J. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Turner, D. L. (Aerospace Corp. El Segundo, CA, United States)
Fennell, J. F. (Aerospace Corp. El Segundo, CA, United States)
Blake, J. B. (Aerospace Corp. El Segundo, CA, United States)
Clemmons, J. H. (Aerospace Corp. El Segundo, CA, United States)
Jaynes, A. N. (Colorado Univ. Boulder, CO, United States)
Baker, D. N. (Colorado Univ. Boulder, CO, United States)
Craft, J. V. (Colorado Univ. Boulder, CO, United States)
Spence, H. E. (New Hampshire Univ. Durham, NH, United States)
Niehof, J. T. (New Hampshire Univ. Durham, NH, United States)
Reeves, G. D. (Los Alamos National Lab. Albuquerque, NM, United States)
Torbert, R. B. (Los Alamos National Lab. Albuquerque, NM, United States)
Russell, C. T. (California Univ. Los Angeles, CA, United States)
Strangeway, R. J. (California Univ. Los Angeles, CA, United States)
Magnes, W. (Space Research Inst. Graz, Austria)
Trattner, K. J. (Colorado Univ. Boulder, CO, United States)
Fuselier, S. A. (Southwest Research Inst. San Antonio, TX, United States)
Burch, J. L. (Southwest Research Inst. San Antonio, TX, United States)
Date Acquired
April 7, 2017
Publication Date
June 20, 2016
Publication Information
Publication: Geophysical Research Letters
Volume: 43
Issue: 12
ISSN: 0094-8276
Subject Category
Space Sciences (General)
Report/Patent Number
GSFC-E-DAA-TN41133
Funding Number(s)
CONTRACT_GRANT: NNG04EB99C
Distribution Limits
Public
Copyright
Other