The plasmapause response to the southward turning of the IMF derived from sequential EUV images

摘要

We statistically examined the plasmapause response to the southward turning of the interplanetary magnetic field (IMF) using sequential global images of the plasmasphere, in order to understand how the convection electric field propagates to the inner magnetosphere. The extreme ultraviolet (EUV) imager on the Imager for Magnetopause-to-Aurora Global Exploration satellite clearly observed inward motion of the plasmapause driven by the southward turning of the IMF. We surveyed the EUV data in the 2000–2001 period and found 16 events. Using the sequential EUV images, we calculated the plasmapause radial velocity, and then estimated the time development of the convection electric field at the plasmapause (E pp). E pp and the solar wind electric field derived from the measurement by the ACE satellite had very similar variations each other, but there surely was a time lag. Consequently, our research indicates that the plasmapause response to the southward turning of the IMF takes 10–30 min. This timescale suggests that the convection electric field penetrates from the magnetopause to the inner magnetosphere through the ionosphere.