联合GRACE卫星轨道及距离变率数据反演地球重力场方法研究

METHOD OF GRAVITY FIELD INVERSION WITH COMBINING GRACE ORBITS AND RANGE-RATE OBSERVATIONS

基于动力学法,研究联合GRACE卫星精密轨道及距离变率数据反演地球重力场的方法,该方法可对重力位系数及卫星初始状态误差同时进行有效校正。通过对各观测值模拟不同的随机误差,研究了不同精度观测值联合反演所能达到的精度,以及用相同精度的观测值进行联合反演时不同采样率对反演结果的影响,模拟计算结果表明：联合反演模式下,当距离变率精度为1μm/s,卫星位置精度为23 cm,速度精度为0.10.5 mm/s时,加速度计精度为（1.0×10^-10-1.0×10^-9）m/s^2比较适合;将距离变率精度由1 um/s提高到0.1 um/s时,反演精度可获得相应提高;在观测值精度一定的情况下,联合反演算法宜采用5 s采样率。

The dynamical method based on the precision orbits and range-rate data of GRACE for recovering gravity field model is discussed,and the gravitational potential coefficients and the satellite’s initial state error can be estimated simultaneously with this algorithm.The gravity field models are recovered with the combined observations with different orbits accuracy and different sampling rate range-rate of GRACE,finally the accuracy of gravity field model recovery are analyzed.The simulated results show that the accuracy of accelerometer from（1.0×10^-10-1.0×10^-9） m/s ^2 is suitable for the combined recovery algorithm,as the range-rate with 1 μm/s accuracy,satellite’s position with 2-3 cm accuracy,and satellite’s velocity with 0.1-0.5 mm/s accuracy.When the accuracy of rang-rate is improved from 1 um/s to 0.1 um/s,the accuracy of recovered model is improved correspondingly;the accuracy of the recovered model based on same accuracy observations with sampling rate of 5 seconds is the hightest accurate.