Thermospheric Density Derived from Two-line Orbital Elements Sets

Abstract:

Two Line Elements(TLE) consists of six mean orbital elements of satellite, one of the elements is ‘mean’ mean motion n_M, which reflects the drag effect of atmosphere on semi-major axis. Atmosphere density along the orbit could be derived through the change of n_M. Before deriving atmosphere density, ballistic coefficient B need to be calculated. We chose satellite CHAMP as our research object, and derived atmosphere density of the year 2003-2005 from TLE data. Density derived from high-accuracy accelerometer could be referred to as real density, and used to estimate the precision of TLE-derived and NRLMSISE-00 model density. The results showed that mean error of TLE-derived density is 3.5-5.8% smaller than model density when geomagnetic was quiet, however, the results is not ideal during the period of geomagnetic storm. The most likely reason is that atmosphere density changes rapidly and was extremely complicated, another possible reason is because of the low temporal resolution of TLE. This part of work needs further research and improvement.