IMF‐driven plasmasphere erosion of 10 July 2000

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 V pp at 2.4 MLT was extracted from the time sequence of EUV images. We show that intervals of V pp < 0 (i.e., erosion) are correlated with intervals of southward (S wd ) 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.