IMF-driven plasmasphere erosion of 10 July 2000

J. Goldstein, B.R. Sandel, W.T. Forrester, and P.H. Rei


On 10 July 2000,the IMAGE EUV imager observed erosion of the nightside
plasmasphere that occurred in two bursts during 5-8 UT. The plasmapause
radial velocity Vpp at 2.4 MLT was extracted from the time sequence of
EUV images. We show that intervals of Vpp < 0 (i.e., erosion) are
correlated with intervals of southward (Swd) interplanetary magnetic
field (IMF), if the solar wind and IMF data are time-delayed by 30
minutes (in addition to a 3.7-minute delay for propagation to the
magnetopause). This suggests that coupling between the solar wind and
the plasmapause, involving processes in the ionosphere and magnetotail,
takes about 30 minutes. A 6:40 UT magnetosphere compression may have
hurried the onset of the second erosion. 

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Accepted by Geophysical Research Letters, 2002