The nongravitational accelerations measured onboard spacecraft for the purpose of modeling the Earth’s gravitational field but also for the investigation of the upper atmosphere are crucial. This study is focused on two LEO satellites, GRACE and GRACE–FO, which carry an accelerometer that measures the nongravitational accelerations, with the most dominant being the drag and the solar radiation pressure. This study presents the physical models of the nongravitational accelerations presented in the literature for the two missions and investigates how the nongravitational acceleration measurements are affected during different time periods of the solar cycle. In addition, the effect of the penumbra transitions in the three axes of the accelerometers which present as jumps in the measurements are presented. Lastly, the response of the accelerometers is investigated during minor and major geomagnetic storms that appeared during the last two solar cycles, the 24th and the 25th.
Part of the book: Ionosphere