基于实时观测数据的大气密度模式修正

针对国际大气密度模式NRLMSISE-00, 以中国神舟飞船探测数据为基础, 提出一种基于实时大气密度观测数据的模式修正方法. 通过计算分析模式计算结果与探测数据的误差分布特征, 针对地磁相对平静期(Ap≤ 30)模式计算的误差特点, 建立了一种平均误差修正方法, 即认为在相对平静期, 在相同纬度和地方时, 模式误差基本相同, 某一时刻模式预测误差可以近似用与其相同纬度和地方时的平均误差来替代, 从而对模式预测结果进行修正. 以神舟4号探测数据为基础, 通过对模式预测结果采用两种方式进行修正, 可以看到模式误差得到了一定的改善. 采用误差库累积准实时修正, 修正后的误差由原来的20 %降至6 %; 采用误差库5天滑动预报修正后, 模式提前1, 2, 3天的预测误差由原来的20 %分别降至7.8 %, 9.4 %和10.5%. 

Atmospheric Density Calibration Using the Real-time Satellite Observation

For low Earth satellites, thermospheric density models are widely used in orbit determination and prediction. However, typical models often show density errors of 15 %~30 % under normal condition and the errors may be much greater during unusually solar and geomagnetic period. Density errors can be translated into orbit errors and effect mission plan, re-entry operations and precise orbit determination. In this paper, on the basis of detected data of Shenzhou, a kind of model calibration is expected to be developed on real-time detected data. By analyzing and comparing the character of density error for the national atmosphere model NRLMSISE-00, a kind of average calibration method is developed for relative quiet geomagnetic field (Ap≤30). During the quiet geomagnetic field, the errors of model at the same local time and latitude are considered approximately identical, so the error may be substituted by average error at the same station. The results of model are tested based on Shenzhou 4 data by two means and both are improved in accuracy. The errors of 20 % decreased to 6 % by real-time error calibration. The errors of one day in advance decreased to 7.8 %, two days in advance decreased to 9.4 % and three days in advance decreased to 10.5 %.