固定模糊度的GRACE-FO卫星简化动力学定轨精度分析

对GRACE-FO卫星进行精密定轨研究，利用简化动力学方法处理其14 d的星载GPS数据并进行精度分析。通过载波相位残差分析、重叠弧段比较、参考轨道比较以及KBR检核，对比通过UPD方法固定模糊度参数的简化动力学轨道与浮点解轨道。结果表明，GRACE-FO卫星固定解轨道的载波相位残差约为1 cm，比浮点解大1～2 mm。3 d固定解重叠弧段差异的RMS值在R、T、N方向上均小于等于9.4 mm，优于浮点解的12.4 mm。与GFZ提供的精密科学轨道相比，GRACE-C卫星简化动力学固定解轨道在各方向上差异的RMS均值均小于1 cm，表明解算得到的轨道与PSO具有较高的一致性。固定模糊度后K波段测距(K-band ranging)检核残差的RMS均值从9.6 mm下降到6.7 mm，说明固定解能够进一步提升GRACE-FO卫星间的相对位置精度。因此，模糊度固定能够改善GRACE-FO卫星的定轨精度，提供更可靠的轨道服务。

Precision Analysis on Reduced-Dynamic Orbit Determination of GRACE-FO Satellite with Ambiguity Resolution

We carry out precise orbit determination research of the GRACE-FO satellite, and process the 14-day on-board GPS data by the reduced-dynamic method, and perform accuracy analysis. For the comparison of the reduced-dynamic orbit with ambiguity resolution parameters by UPD method and the float solution orbit, we carry out carrier phase residual analysis, overlapping arc comparison, reference orbit comparison, and KBR check. The results show that the carrier phase residual of the fixed solution orbit of the GRACE-FO satellite is about 1 cm, which is 1 to 2 mm larger than the float solution. The RMS of 3-day fixed solution overlapping arc difference is less than or equal to 9.4 mm in the radial, tangential and normal directions, which is better than float solution of 12.4 mm. Compared with the precision scientific orbit provided by GFZ, the GRACE-C satellite reduced-dynamic fixed solution orbit has a mean RMS of less than 1 cm in all directions, which means that the calculated orbit has a high consistency with PSO. The residual RMS value of the KBR check after ambiguity resolution decreases from 9.6 mm to 6.7 mm, which indicates that the fixed solution can further improve the relative position accuracy between GRACE-FO satellites. The ambiguity resolution can improve the orbit determination accuracy of GRACE-FO satellite and provide more reliable orbit service.