Ion Signatures of Magnetospheric Regions and Boundaries: The September 24,1999 CME Event

Michael O. Chandler (ES83/Space Science Laboratory, Marshall Space Flight Center, AL 35812,

P. D. Craven (ES83/Space Science Laboratory, Marshall Space Flight Center, AL 35812,

T. E. Moore (Interplanetary Physics Branch Laboratory for Extraterrestrial Physics, GSFC, Greenbelt, MD 20771,


On 24 September 1999 Earth's magnetosphere was impacted by a large CME with an associated shock front. This impact moved the magnetopause inward by several Re and pushed dayside magnetospheric boundaries anti-sunward by more than 1 Re. The resulting observations from the Polar spacecraft, which was located over the northern polar cap, show signatures of the polar cap, the cusp, and the mantle as these regions were moved across the spacecraft position. An enhanced Cleft Ion Fountain outflow was observed as Polar moved sunward towards the cusp following the shock passage. Analysis of these data shows the velocity filter/mass spectrometer nature of the CIF in association with anti-sunward convection. These signatures are used to investigate time scales for reconnection, energy transfer to the ionosphere, and CIF outflow generation.