- University of Bern, Astronomical Institute, Berne, Switzerland (adrian.jaeggi@aiub.unibe.ch)
Coronal mass ejections (CMEs) from the Sun can cause geomagnetic storms which cause the thermosphere to expand. This leads to enhanced air drag for satellites in low Earth orbit (LEO). This work focuses on the evaluation of orbital decay with a focus on selected geomagnetic storm events. Using the Bernese GNSS Software (BSW), reduced-dynamic orbits of different LEO satellites are computed from GNSS data of on-board receivers, where non-gravitational accelerations are modelled by means of estimated empirical piecewise-constant accelerations (PCAs). The orbital decay is then calculated by using the PCAs, or, in case of the GRACE Follow-On satellite, calibrated accelerometer data, to solve Gauss’s perturbation equation for the satellite’s semi-major axis. This method is compared to an approach where a fit model is applied to the osculating semi-major axis derived from the reduced-dynamic orbits computed by BSW. The fit model consists of a piece-wise linear model of the time-varying mean orbital decay and the time-varying amplitudes of the most dominant periodic oscillations. The results of both methods are compared and found to be similar for large orbital decays induced by CMEs. But the fit model struggles with low orbital decay. The Gaussian perturbation equation approach is far more precise than the fit model and can react, e.g., instantaneously to satellite maneuvers which change the semi-major axis. For satellites without an on-board accelerometer, PCAs can be estimated and used for the numerical integration.
How to cite: Walter, L., Mercea, V.-M., Arnold, D., and Jäggi, A.: Orbital decay of low Earth orbiting satellites during geomagnetic storms, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11256, https://doi.org/10.5194/egusphere-egu25-11256, 2025.