基于精密光压模型的GRACE卫星加速仪校标新方法∗

摘要

In this paper, we adopt the precise solar radiation model to compute the real perturbation force caused by solar radiation on the GRACE satellites, and estimate the scale factors of accelerometer’s y-axis and z-axis, which are set to be constant values in the following calibration process. Then, we estimate the rest of four parameters by the dynamic orbit determination (OD), such as the scale factor of x-axis, and the biases of three axes. Through these steps, we get the daily calibration parameters from 2002 to 2014. The average value and standard deviation of scale factors of x-, y-, and z-axis are 0.9435 ± 0.0187, 0.9393 ± 0.0444, 1.0371 ± 0.0391 for GRACE-A, and 0.9313 ± 0.0170, 0.9488 ± 0.0452, 1.0274 ± 0.0446 for GRACE-B, respectively. Different from our early work, the new method constrains the scale factors of y-axis and z-axis with the precise solar radiation model, which could decrease the measurement error’s effect on the weak-signal axes (y, z) as well as reduce the correlation between scale factor and bias, and eventually improve the stability of calibration parameters. Taking the results of y- and z-axis of GRACE-A as example, the standard deviation of scale factors with the new method is about 0.0391–0.0444, while the early results by the unconstrained dynamic orbit determination are about 0.21–0.31. It is shown that the standard deviations of scale factor with this paper’s method have been decreased by more than 78%, and those of bias have been decreased by more than 85%. Therefore, the calibration parameters estimated with the new method are more stable than our early results, and will have a special value for the study on the rotation speed and wind field of the earth’s thermosphere.%以精密光压模型为工具,计算GRACE(Gravity Recovery and Climate Exper-iment)卫星受到的太阳光压摄动力,以此对加速仪的y轴、z轴的尺度因子进行估算并固定为常值,然后通过动力学定轨方法对另外4项加速仪校标参数(x轴尺度和偏差, y、z轴的偏差)进行求解,得到了2002–2014年每一天的加速仪校标参数.统计结果如下：GRACE-A卫星x、y、z 3个轴的尺度因子分别为0.9435±0.0187、0.9393±0.0444、1.0371±0.0391, GRACE-B卫星3个轴的尺度因子分别为0.9313±0.0170、0.9488±0.0452、1.0274±0.0446.与早期工作的差异在于,在动力学法定轨之前,先利用精密光压模型对y、z轴的尺度因子进行约束,有助于减小资料误差对弱信号轴(y, z)的影响,从而提高校标结果的稳定性.以GRACE-A卫星的y、z轴为例,尺度因子的标准差约0.0391–0.0444,而未加光压模型约束的动力学校标方法的标准差为0.21–0.31,新方法得到的标准差降幅超过78%；同样,线性偏差的标准差降幅超过85%.因此,新方法得到的校标参数更加稳定,对于研究大气旋转效应以及热层大气风场具有特殊的价值.