Theremospheric variations from GNSS and accelerometer observations on GRACE and Swarm

The upper layer of the Earth’s atmosphere is highly variable in space and time due to anacoustic dynamics actions through the collisions between the ionospheric plasma and the neutrals. Monitoring and understanding thermospheric air mass density variations are important for the orbital decay and space physics. In the last half century, thermospheric air mass density variations and climatology have been studied and modelled, but were subject to large uncertainty due to using empirical models and less observations. Nowadays, the GPS precise orbit determination and accelerometers on satellites provide a unique opportunity to estimate and study air density variations with unprecedented accuracy. In this paper, the recent results and advances in the theremospheric variations are presented from GPS POD and accelerometer data on GRACE and Swarm satellites as well as future challenges and perspective.