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Density Variations in the Earth's Magnetospheric CuspsSeven years of measurements from the Polar spacecraft are surveyed to monitor the variations of plasma density within the magnetospheric cusps. The spacecraft's orbital precession from 1998 through 2005 allows for coverage of both the northern and southern cusps from low altitude out to the magnetopause. In the mid- and high- altitude cusps, plasma density scales well with the solar wind density (n(sub cusp)∕n(sub sw) approximately 0.8). This trend is fairly steady for radial distances greater then 4 R(sub E). At low altitudes (r less than 4R(sub E)) the density increases with decreasing altitude and even exceeds the solar wind density due to contributions from the ionosphere. The density of high charge state oxygen (O(greater +2) also displays a positive trend with solar wind density within the cusp. A multifluid simulation with the Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme MHD model was run to monitor the relative contributions of the ionosphere and solar wind plasma within the cusp. The simulation provides similar results to the statistical measurements from Polar and confirms the presence of ionospheric plasma at low altitudes.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Walsh, B. M. (Boston Univ. Boston, MA, United States)
Niehof, J. (New Hampshire Univ. Durham, NH, United States)
Collier, M. R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Welling, D. T. (Michigan Univ. Ann Arbor, MI, United States)
Sibeck, D. G. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mozer, F. S. (California Univ. Berkeley, CA, United States)
Fritz, T. A. (Boston Univ. Boston, MA, United States)
Kuntz, K. D. (Johns Hopkins Univ. Baltimore, MD, United States)
Date Acquired
March 17, 2017
Publication Date
March 15, 2016
Publication Information
Publication: Journal of Geophysical Research: Space Physics
Volume: 121
Issue: 3
ISSN: 2169-9380
Subject Category
Plasma Physics
Report/Patent Number
Funding Number(s)
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