Sun-synchronous thermal tides in exosphere temperature from CHAMP and GRACE accelerometer measurements

[1] This paper focuses on the sun-synchronous diurnal (DW1) and semidiurnal (SW2) tidal components of neutral exosphere temperature derived from contemporaneous drag measurements made from the CHAMP and GRACE satellites. Densities are converted to exosphere temperatures using the parametric relationship that exists between density and temperature in the NRLMSISe00 empirical model. Daily, seasonal and solar-cycle dependencies of DW1 and SW2 in exosphere temperature are elucidated, and similarities and differences with NRLMSISe00 are detailed. In addition, using TIMED/SABER measurements between 80–110 km and viscous tidal theory, it is demonstrated that the measured seasonal-latitudinal variation of the semidiurnal exosphere temperature amplitude is dominated by the part excited in-situ in the thermosphere, as opposed to those tidal components that propagate upwards from the lower atmosphere.