Using Temporal Relationship of Thermospheric Density With Geomagnetic Activity Indices and Joule Heating as Calibration for NRLMSISE-00 During Geomagnetic Storms

The responses of thermospheric densities to geomagnetic activity indices and Joule heating are analyzed during 265 geomagnetic storms and can be used to calibrate the model NRLMSISE-00 with neutral mass density observed at 400 km based on the CHAMP satellite from 2002 to 2008. In this work, the geomagnetic activities at high and low latitudes are identified by AE indices and Dst indices. During geomagnetic storms, Joule heating and its impacts on the thermospheric density are calculated by the Weimer-2001 electric potential model and the DMSP spacecraft. The results show that the response of thermospheric density to both AE and Dst index takes a longer time as geomagnetic storms intensify. During weak and moderate storms, density delays AE indices for about 0–1 hr, while it is 2–4 hr for intense storms. In addition, the time differences between Dst indices and AE indices increase as storms intensify. During weak and moderate geomagnetic storms, the difference in the time corresponding to Dst indices with the time when AE indices peak is only 1–2 hr, while it increases to 3–5 hr for the intense storms. Furthermore, the calibration of the NRLMSISE-00 model results can reproduce the storm-time thermospheric density well, with the Mean Relative Error (MRE) between density observation and model decreasing from 40% to 10% after the correction.