Thermospheric Density From Analysis of 6-YearGRACE Accelerometer Data

摘要

The pair of the GRACE (Gravity Recovery And Climate Experiment) satellites has been flying in near circular and polar orbits over 6-year since 17, March 2002. The satellite orbit is decaying with ～4 km/year starting at ～485 km altitude due to drag. During this period, solar activity down from its high to minimum of Solar cycle 23 in early of January 2008, and is starting to the next solar cycle. The high-accuracy accelerometer data from the pair of GRACE satellites were analyzed to derive the total atmospheric neutral density and its variations as well as winds to characterize the density variability in terms of solar and geomagnetic indices. In addition, the two GRACE satellites are identical and separated by ～200 km. The accelerometer measurements of the non-gravitational accelerations from two satellites are independent to each other. The differences in the ACC data and derived densities from two GRACE satellites were analyzed to estimate the uncertainty of the derived density at GRACE altitude, and study the spatial features in density variations with a resolution of a few hundreds kilometers. The results will be presented in comparison with those density models, including the DTM-78, NRLMSIS-00, and HASDM.