Changes in upper mesospheric and lower thermospheric temperatures caused by energetic particle precipitation

A statistical evaluation on the upper mesospheric and lower thermospheric temperature effects caused by energetic particle precipitation is performed on the basis of data from the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) and NOAA 15, 16, and 17 satellites. By combining particle measurement from the medium energy proton and electron detectors (MEPED) on board the NOAA satellites, maps of the global particle precipitation can be obtained close in time to the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) temperature retrieval. Using large data sets, sorted by season, local time, and geomagnetic latitude, we investigated whether there are significant temperature effects in the upper mesosphere and lower thermosphere associated with the energetic particle precipitation. During both May/June and October/November 2003, we found a temperature increase related to particle precipitation at all heights above 100 km. In general, we did not find a consistent immediate temperature modification below 100 km associated with increased particle flux. Considering the temperatures retrieved during the extraordinary large geomagnetic storms in late October 2003, we found a cooling effect associated with energetic particle precipitation.