Tidal Signals in GOCE Measurements and TIME-GCM
Haeusler, Kathrin1; Hagan, Maura E.1; Lu, Gang1; Forbes, Jeffrey M.2

The GOCE satellite with its onboard accelerometer provides unique in-situ measurements of the neutral density and zonal wind near 270 km altitude, and complements measurements made by the CHAMP satellite at about 300 km. The sun-synchronous orbit of GOCE allows measurements in only two local time sectors, which complicates tidal analysis. It has been recently established that atmospheric tides generated in the lower atmosphere significantly influence the geospace environment. In order to support tidal diagnostics for GOCE measurements the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) is used. The model was run for the mid-November to mid-December 2009 time period when GOCE and CHAMP were in a near co-planar orbit. Tidal and planetary wave forcing that represents prevailing atmospheric conditions was applied at the lower boundary. The TIME-GCM outputs are sampled along the GOCE and CHAMP orbits, and analyzed in terms of ascending/descending orbit node differences to identify tidal signatures for comparison with the satellite data while the complete model outputs are used to unambiguously characterize the simulated atmospheric tides.