Probing the Altitudinal Density Profile of the Thermosphere using Loss Cone Measurements

A novel method for remotely sensing thermospheric parameters and the response of the high-latitude thermosphere to differing levels of solar and geomagnetic activity will be presented and discussed. This method utilizes the loss cone structure formed from charged particles precipitating onto the upper atmosphere to probe thermospheric density as a function of altitude. The dependence of the loss cone structure on incident particle energy can be mapped to different mirror point altitudes, thus yielding an altitudinal profile of the thermosphere. The principles of this method are illustrated by employing models for the thermosphere, the magnetic field near Earth, and the precipitating particle distributions. This method is explored in further detail using particle distribution measurements gathered by the Fast Auroral Snapshot Explorer (FAST) mission.