空域最小二乘法用于重力卫星误差分析

重力测量卫星性能不仅与轨道参数、载荷误差、数据分辨率等因素密切相关，也与反演算法有关。传统的分析方法如动力学法、短弧法等用于误差分析，不可避免将算法误差引入分析结果，使得分析结论确定性不足。为解决这一问题，提出了空域最小二乘分析法，用空域格网重力扰动数据替代重力卫星载荷数据反演地球重力场，有效避免了算法误差对于分析结果的影响。分析结果表明，重力卫星在500 km轨道高度、一次数据覆盖条件下，测量重力场最高阶数约为240阶，载荷误差为1×10-10 m·s-2·Hz-1/2水平时，测量重力场最高阶数为136阶，其累积重力异常误差为2.7 mGal，累积大地水准面误差为14 cm。要达到最优测量能力，轨道倾角通常不小于89°。为减小地球引力高频信号对于地球重力场低阶位系数估计值的影响，估计位系数最高阶数需大于240阶。

Application of Space-Wise Least Square Method to Error Analysis for Satellite Gravimetry

The performance of satellite gravimetry is determined not only by orbital parameters, sensitivity of payloads, resolution of data, et al, but also by inaccuracy of the Earth gravity recovered methods. In past years, the performance analysis results were unavoidably affected by the mathematical model error from recovering methods such as dynamic method, short-arc integrated method, et al. To solve this problem, space-wise least square method is present. The effects of each items which affected the performance of satellite gravimetry are evaluated by this method. The results indicate that the highest degree of the earth gravity model recovered is 240 for the satellite with 500 km orbital height. Then if the error of payload is 1×10-10 m·s-2·Hz-1/2, the degree of model recovered only approach to 136 with the accumulated gravity anomaly error 2.7 mGal and the accumulated geoid height error 14 cm. In order to achieve the best surveying performance, the orbital inclination should be greater than 89°. While, the max degree of the earth gravity model recovered should be greater than 240 so as to reduce the effect of high frequency gravity signal on low degree coefficients recovered. All these conclusions benefit to satellite designing and data processing.