几何精度因子对GRACE卫星几何轨道精度影响分析

分析了GDOP值与GRACE卫星几何轨道精度之间的关系,发现定轨精度较差的历元其GDOP值普遍较大甚至异常,进一步研究发现GDOP值异常现象是因剔除个别含有粗差的卫星而导致的,进而通过设置GDOP值阈值的方式剔除发生GDOP值异常的历元。实验结果表明,GDOP值阈值设置为50,将大于该阈值的历元剔除,能够有效抑制个别历元精度较差的情况,最终的RMS在地固系X,Y,Z3个方向分别为0.029m,0.043m,0.029m,实现了几何法厘米级精密定轨的目标。

Influence of geometric dilution of precision on the precision of GRACE satellite geometry orbit

The relationship between GDOP and the accuracy of geometry orbit of GRACE satellite is analyzed .It is found that the GDOP value is lagre or even abnormal when the orbitting accuracy is poor , and most of such phenomenon is caused by the exclusion of outlier w hich leads to bad geometry .T herefore the threshold of GDOP is set as 50 to delete the observations of the whole epoch .The real data is used to verify the method .The result shows the method can avoid the new abnormal values resulting from outlier detection and exclusion .The RMS in X ,Y ,and Z direction are 0.029 m ,0.043 m ,and 0.029 m respectively , and the goal of centimeter level precise orbiting is achieved .