Determination of thermospheric winds from GRACE accelerometer data

The accelerometer (ACC) data from GRACE, which are a measure of the non-gravitational forces acting on the satellites, are particular well-suited for exploring the upper atmospheric density variations and the thermospheric neutral winds as well. The onboard high accuracy accelerometer is very sensitive to all of the nongravitational forces, including drag and winds, solar and earth radiation pressure, and lifting forces due to the complex shape of the GRACE satellite and flight altitude. The effects of the radiation pressure and lifting forces on GRACE spacecraft must be considered, particularly for the determination of the thermospheric neutral winds. Model error of the solar radiation reflectivity coefficients could lead to tens to hundreds m/s for the zonal winds derived from ACC data, particularly over high-latitude area In addition, the cross-track component experiences most of the attitude control thrust effects. The original unfiltered 10 Hz ACC data have to be processed in order to eliminate those spike-like accelerations. This paper presents the procedure and theory for the analysis of the 10 Hz ACC data for the determination of the atmospheric winds, and some preliminary results are presented.