Response of the thermosphere to Joule heating and particle precipitation

Abstract

We have used output from the Weimer Joule heating model (2005) and the Air Force High Accuracy Satellite Drag Model (HASDM) to study the response of the thermosphere to Joule heating. Our study period of 15 January to 29 June 2001 contains a number of large and small magnetic storms during which thermospheric heating events occurred. We find that a new Joule heating model (Weimer, 2005), combined with the energy input provided by precipitating particles (NOAA/TIROS hemispheric power index), can supply more than enough energy to account for the change in total thermospheric internal and gravitational potential energy during magnetic storms. In the smaller storm heating events the energy input is about equally divided, with Joule heating only slightly dominant over particle precipitation. In the larger events, Joule heating clearly dominates. We find that the thermosphere responds globally in just 3–6 hours to an increase in energy input.