15:30 〜 16:30
[G06-P-02] Calibration of empirical thermospheric models by using laser observations to near-Earth orbiting spherical satellites
The thermosphere causes by far the largest non-gravitational perturbing acceleration of near-Earth orbiting satellites. Especially between 80 km and 600 km, the thermospheric density distribution and variations are required to accurately model this force. So far, mainly accelerometers onboard of satellites are used to measure the thermospheric density. However, such type of satellite is usually of complex shape and any error or miss-modelling of the satellite drag coefficients will directly propagate into the derived thermospheric density values.
At GFZ, an empirical model of the thermospheric mass density has been developed by using 9 years of CHAMP observations. The model is based on seven ˋkey' parameters, namely height, solar flux, season, magnetic local time, geographic latitude, and magnetic activity.
A completely different approach is to use satellite laser ranging (SLR) measurements to satellites equipped with retro-reflectors to determine the most accurate satellite orbit. These measurements are sensitive to small perturbations acting on the satellite. In order to minimize the error induced by wrong satellite macro-models, we use ranging observations to satellites with a simple spherical shape. Therefore, the derived thermospheric density values can be seen as ˋabsolute' density values.
In this study, we use SLR observations at least to the four ANDE satellites with altitudes between 350 km and 400 km to calibrate the empirical model developed at GFZ. The main features of the GFZ model are then compared to standard thermospheric models for different solar activity conditions.
At GFZ, an empirical model of the thermospheric mass density has been developed by using 9 years of CHAMP observations. The model is based on seven ˋkey' parameters, namely height, solar flux, season, magnetic local time, geographic latitude, and magnetic activity.
A completely different approach is to use satellite laser ranging (SLR) measurements to satellites equipped with retro-reflectors to determine the most accurate satellite orbit. These measurements are sensitive to small perturbations acting on the satellite. In order to minimize the error induced by wrong satellite macro-models, we use ranging observations to satellites with a simple spherical shape. Therefore, the derived thermospheric density values can be seen as ˋabsolute' density values.
In this study, we use SLR observations at least to the four ANDE satellites with altitudes between 350 km and 400 km to calibrate the empirical model developed at GFZ. The main features of the GFZ model are then compared to standard thermospheric models for different solar activity conditions.