Changes in the Plasma Content in the Inner Magnetosphere During the March 31,
2001 event: IMAGE/RPI Sounding Observations

Bodo W Reinisch 1 (978-934-4903; Bodo_Reinisch@uml.edu)
Xueqin Huang 1 (978-934-4926; xueqin_huang@uml.edu)
Paul Song 1 (978-934-4905; paul_song@uml.edu)
Ivan Galkin 1 (978-934-4912; ivan_galkin@uml.edu)

1 Center for Atmospheric Research, University of Massachusetts 600 Suffolk St,
  Lowell, MA 01854, United States 

During the March 31, 2001 event the solar pressure was more than 40
times greater than its normal with sustained southward interplanetary
magnetic field, conditions for a major magnetic storm. The Kp index went
up to near 9. During the event, the IMAGE orbit was near the
noon-midnight meridian monitoring the magnetospheric responses at local
noon and midnight. The Radio Plasma Imager on IMAGE conducted echo radio
sounding experiments that measured the plasma density distribution along
the magnetic field. Observations show that the total content of the
plasma changed dramatically during the event. The dayside density
dropped significantly during the storm and we also observed the
refilling process after the storm. There is evidence for an increased
density on the nightside during the event, which may be the result of
the higher solar wind density. Quantitative assessment of the density
variations during the event and the refilling process afterward will be
presented.