Simultaneous observations of the exterior cusp region

A case study is presented analyzing the properties and spatial extent of the exterior cusp region. The dynamic nature of the exterior cusp makes the large scale properties difficult to measure using a single spacecraft. We use simultaneous cusp observations of the four Cluster spacecraft as well as the Polar spacecraft to monitor the region. On 10–11 March 2006 all five spacecraft observed the exterior cusp in the southern hemisphere mapping out an extended region in latitude spanning 4.5 RE (and possibly up to 9 RE) along the magnetopause. The depth, or dimension of the diamagnetic exterior cusp perpendicular to the magnetopause is measured to be 1.3 RE with simultaneous measurements from the Cluster spacecraft. The multipoint observations provide a unique view of the diamagnetic exterior cusp showing a spatially extended region.

► The cusp diamagnetic cavity extends 4.5–9 RE tangent to the magnetopause.
► The cusp diamagnetic cavity extends at least 1.2 RE perpendicular to magnetopause.
► Observations of an extended exterior cusp agree with high resolution modeling.
► Large exterior cusp region has implications for particle trapping and acceleration.