利用能量法由沿轨扰动位数据恢复位系数精度分析

Accuracy Analysis of Geopotential Coefficients Recovered from In-situ Disturbing Potential by Energy Conservation Method

讨论了在基于能量法确定地球重力场模型的过程中,利用最小二乘方法由沿轨扰动位数据解算位系数时法方程的特性,在该问题中,法方程只与卫星轨道有关。基于这一特点,阐明了最小二乘解算结果与是否使用参考重力场模型是无关的。在此基础上,根据不同的噪声水平,模拟了4种不同精度的沿轨扰动位观测值。分别进行了重力场模型恢复并分析了其恢复精度。结果表明,在现有加速度计校准水平下,能量法恢复重力场模型难以达到动力法的精度,用于时变研究尚存在一定的困难。

The characteristics of the normal equation created in recovering the earth gravity model （EGM） by least-squares （LS） adjustment from the in-situ disturbing potential has been discussed in detail. It can be concluded that the normal equation of this type of problems depends only on the orbit. Based on this characteristic, whether a reference field is used or not has no effects on the LS solution is explained. Staring from this point, four sets of disturbing potential on the orbit with different level of noise have been simulated and used to recover the EGM. The results show that on the current accuracy level of the accelerometer calibration, the accuracy of the EGM by LS is not sufficient to reflect the time variability of the EGM as the dynamical method has revealed.