A Cusp Density Enhancement Study using e-POP Satellite Data

Abstract:

CHAMP satellite observations have confirmed neutral density enhancements which are localized to the high latitude polar cusp region. These small-scale density structures are consistently correlated with strong fine-scale field-aligned currents. A possible driver of these density enhancements is soft electron precipitation which, through processes associated with ion-outflow, results in a density enhancement in the cusp vicinity at the altitudes observed by CHAMP. We investigate this mechanism with recent observations from the CASSIOPE / e-POP satellite and numerical simulations. In-situ data for selected cusp transit events are presented. Numerical simulation predictions are discussed comparing two electron-precipitation models: a fine-scale ion-outflow model and a global-scale Joule heating / increased conductivity model (CMIT).