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Wing & Newell 2000
Wing, S. and Newell, P.T. (2000). Quiet time plasma sheet ion pressure contribution to Birkeland currents. Journal of Geophysical Research 105: doi: 10.1029/1999JA900464. issn: 0148-0227.

Birkeland currents transport magnetic tangential stress resulting from J¿B forces, which, in the plasma sheet, are balanced by the pressure gradient, ∇p. However, derivation of nightside Birkeland currents from ∇p observationally has not been possible because pressure must be known everywhere in the plasma sheet at high resolution, which in situ satellites have been unable to provide. Recently, a method of inferring plasma sheet temperature, density, and pressure from low-altitude satellites was developed. The quiet time Birkeland currents (or J) are computed from the pressure profile derived from DMSP F8, F9, F10, and F11 data for the year 1992 and magnetic field from a modified Tsyganenko [1989> magnetic field model. Our results show that (1) the region 1 Birkeland currents exhibit a dawn-dusk asymmetry which can be explained by the dawn-dusk asymmetry in the plasma pressure arising if the near-Earth plasma sheet ions are supplied largely by the deep tail plasma sheet and LLBL ions undergoing E¿B earthward and gradient/curvature duskward motions; (2) the average region 1 J is -0.6 and 0.7 nA/m2 near the neutral sheet (negative current density indicates the currents flow out of the ionosphere and positive means into the ionosphere); and (3) the current system tailward/poleward of the region 1 has the opposite polarities from those in region 1 and apparently is generated from the midnight pressure maximum. These results are fairly consistent with those previously obtained with in situ magnetometer measurements. ¿ 2000 American Geophysical Union

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Abstract

Keywords
Ionosphere, Current systems, Ionosphere, Ionosphere/magnetosphere interactions, Magnetospheric Physics, Current systems, Magnetospheric Physics, Magnetosphere/ionosphere interactions
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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