Contribution of Joule heating and soft particle precipitation to the cusp neutral density enhancement

CHAMP observations often show thermospheric density enhancements in the cusp region, which require a persistent heating system to maintain them. Due to the limitation of the observations, the heating mechanism has not been confirmed and no conclusive explanation for the neutral density enhancement has been offered. To unveil the mystery of the neutral density enhancement in the cusp, different heating mechanisms including Poynting flux and soft particle precipitation will be analyzed systematically using DMSP satellite measurements and their impacts on the neutral density will be simulated in GCMs. A detailed data-model comparison will focus on the January 21, 2005 interval.