Overcooling in the upper thermosphere during the recovery phase of the 2003 October storms

During geomagnetically active periods, the NO density and cooling rate in the auroral regions increase significantly as a result of particle precipitation and Joule heating. Previous studies have shown that the time for NO density to recover to quiet time levels is longer than that of the thermosphere temperature or density recovery.

This study explores the implications of these different recovery rates for the post-storm thermosphere. Thermosphere densities retrieved from the CHAMP and GRACE accelerometer measurements and NO cooling rates measured by TIMED/SABER are used to examine their variations during the post-storm period of the October 2003 geomagnetic storms. It was found that thermosphere densities at both CHAMP and GRACE altitudes recovered rapidly and continuously decreased below the quiet time densities during the post-storm period, especially at middle latitudes.