HASDM修正方法分析与评估

分析Jacchia70（J70）热层模式原理、美国空军高精度卫星拖曳模型（HASDM）的修正方法及选取球面调和函数的原因.推导模式密度对球谐系数（SH）的偏导数，给出利用模式密度泰勒展开进行线性化处理、迭代求解球谐系数的具体过程.针对2003年10月29日大磁暴事件，基于CHAMP和GRACE A/B卫星加速度计实测密度，进行修正方法的性能评估.统计相对误差的均值及标准差变化:改进前分别为-81.7%，74.4%；改进后分别为-5.9%，53.1%，验证了改进算法的有效性.从热层上下边界温度角度，详细分析了热层模式动态修正原理，研究结果为类HASDM修正模式的工程应用提供了理论基础. 

Analysis and Evaluation of High Accuracy Satellite Drag Model

The principle of Jacchia70 thermosphere model and the correction method of HASDM are analyzed. The partial derivative of mode density with respect to Spherical Harmonic coefficient (SH) is derived, and the specific process of solving spherical harmonic coefficient iteratively is given by means of mode density Taylor expansion. Based on the Accelerometer data of CHAMP and GRACE A/B satellites, one big geomagnetic storm event during 29 October 2003 was selected to test the validation of the method. The mean and stand deviation of relative errors are -81.7%, 74.4% and -5.9%, 53.1% before and after correction. It shows that this method is perfect. In the view of the upper and lower boundary temperatures of the thermal layer, and the principle of dynamic modification of the thermal layer model is analyzed in detail.The results provides a theoretical basis for the engineering practice of HASDM-like modification model.