Analysis of thermospheric density variations neglected in modern atmospheric models using accelerometer data

The accuracy of the atmospheric density and its spatiotemporal variations given by the NRLMSISE-00 atmosphere model at the solar minimum are estimated using density measurements of the CACTUS microaccelerometer at heights of 270–600 km. The model errors are found to be noticeably (by a factor of 2–3) higher than the errors in atmospheric densities obtained from satellite drag data at solar minima. Microaccelerometer density data are used to study short-period (during one orbit) spatiotemporal density variations. The analysis of density variations over one orbit reveals orographic and continental effects. The amplitudes of the continental and orographic effects are estimated at 10–15% at a height of 270 km and 40% at a height of 600 km.