Satellite Based Neutral Densities and Their Application to Solar Storm Analysis

The Graz University of Technology processes thermospheric neutral densities for several satellite missions, primarily using GNSS observations (SWARM, TerraSAR-X, Sentinel etc.) and accelerometer measurements (CHAMP, GRACE, GRACE-FO). However, before accelerometer measurements can be used for this purpose, they must be calibrated. Until recently, we used the already established calibration scheme from gravity field recovery to also estimate densities. These two calibration schemes are now independent of each other. Since our last release, we have updated the satellite force modeling, unified some parametrizations and introduced a variable molecular mass to account for the thermosphere's dependence on the solar cycle. All of these changes are included in our new release.

Currently, combining all estimation techniques yields a dataset spanning approximately 25 years. This dataset is a potent tool for studying the impact of space weather. During this period, numerous geoeffective CMEs occurred, as is clearly visible in the density time series. This study emphasizes the effects of recent severe solar storms. We present these extreme events and contextualize them within the last two solar cycles. To support further research, we explain our publishing scheme and provide download links.