Cluster energetic electron survey of the high-altitude cusp and adjacent regions

A statistical study of the energetic electron population (E > 37 keV) in the high-altitude cusp and surrounding regions is conducted with 7 years of data from the Cluster spacecraft. The progression of Cluster's orbit during this period allows for a wide range of latitude on the dayside magnetosphere to be surveyed. Locations of the spacecraft are adjusted to account for changes in the solar wind and geomagnetic activity measurements. The survey shows (1) frequent presence of energetic electrons within the high latitude trapping region and exterior cusp, (2) energetic electron flux dropping off rapidly with distance from the magnetosphere into the magnetosheath, (3) a similar spectral power law for the electrons in the outer high latitude trapping region as the exterior cusp, and (4) a pitch angle distribution in the cusp peaking at 90°. These findings indicate the energetic electron population on potentially open field lines in the exterior cusp likely is fed by both the high latitude trapping region as well as local acceleration.