Upper Atmospheric Density Retrieval from Accelerometer on Board GRACE Mission

Abstract

In order to improve the prediction accuracy of LEO, it is essential to build up an accurate atmospheric model for density prediction. However, most existing atmospheric models belong to the type of semi-empirical model, thus the data sets are not of homogeneous quality and have limited geographical and temporal coverage. Since the space-borne accelerometer could measure the total non-conservative accelerations acting on LEO directly, the atmospheric drag component could be isolated with the help of the solar and earth albedo radiation pressure models, then the atmospheric density can be calculated, which provides necessary data for making evaluation and improvement of the existing atmospheric models. This paper describes the method to retrieve the upper atmospheric density from accelerometer in detail, 3 months of observations spanning from May 2013 to July 2013 are selected to do the experiment, we use the dynamical orbit determination strategy to calibrate the accelerometers, and then retrieve the air density at the altitude of GRACE Mission. The results show that prediction models cannot exhibit the density variation in high frequency, and the in situ measurements are very useful in density analysis, in addition, it is validated that atmospheric density has a positive correlation with the solar activity intensity.