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Plasma Distribution in Mercury's Magnetosphere Derived from MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer ObservationsWe assess the statistical spatial distribution of plasma in Mercury's magnetosphere from observations of magnetic pressure deficits and plasma characteristics by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The statistical distributions of proton flux and pressure were derived from 10months of Fast Imaging Plasma Spectrometer (FIPS) observations obtained during the orbital phase of the MESSENGER mission. The Magnetometer-derived pressure distributions compare favorably with those deduced from the FIPS observations at locations where depressions in the magnetic field associated with the presence of enhanced plasma pressures are discernible in the Magnetometer data. The magnitudes of the magnetic pressure deficit and the plasma pressure agree on average, although the two measures of plasma pressure may deviate for individual events by as much as a factor of approximately 3. The FIPS distributions provide better statistics in regions where the plasma is more tenuous and reveal an enhanced plasma population near the magnetopause flanks resulting from direct entry of magnetosheath plasma into the low-latitude boundary layer of the magnetosphere. The plasma observations also exhibit a pronounced north-south asymmetry on the nightside, with markedly lower fluxes at low altitudes in the northern hemisphere than at higher altitudes in the south on the same field line. This asymmetry is consistent with particle loss to the southern hemisphere surface during bounce motion in Mercury's offset dipole magnetic field.
Document ID
20150010108
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Korth, Haje
(Johns Hopkins Univ. Laurel, MD, United States)
Anderson, Brian J.
(Johns Hopkins Univ. Laurel, MD, United States)
Gershman, Daniel J.
(Michigan Univ. Ann Arbor, MI, United States)
Raines, Jim M.
(Michigan Univ. Ann Arbor, MI, United States)
Slavin, James A.
(Michigan Univ. Ann Arbor, MI, United States)
Zurbuchen, Thomas H.
(Michigan Univ. Ann Arbor, MI, United States)
Solomon, Sean C.
(Carnegie Institution of Washington Washington, DC, United States)
McNutt, Ralph L.
(Johns Hopkins Univ. Laurel, MD, United States)
Date Acquired
June 8, 2015
Publication Date
April 25, 2014
Publication Information
Publication: Journal of Geophysical Research: Space Physics
Publisher: American Geophysical Union
Volume: 119
Issue: 4
Subject Category
Plasma Physics
Report/Patent Number
GSFC-E-DAA-TN22896
Funding Number(s)
CONTRACT_GRANT: NNG11PL10A
CONTRACT_GRANT: NNH06CC03B
CONTRACT_GRANT: NASW-00002
CONTRACT_GRANT: NAS5-97271
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
magnetic
spatial
plasma
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