利用LEO星群反演地球重力场低阶带谐项变化的交叠点法

新一代重力卫星计划主要依靠高精度星载加速度计（ACC）、星间测距系统（KBR）或星载梯度计(SGG)进行地球重力场探测。这类系统因实现困难，成本较高，很难大量实施。而搭载高精度星载GPS接收机的低轨卫星（low earth orbit, LEO）可以相对较低成本获取LEO卫星的精密轨道。卫星精密轨道一方面服务于LEO的主任务（如遥感，气象等）；另一方面可以将这类LEO卫星和星座综合起来，构成LEO星群（Cluster），LEO星群精密轨道数据包含的丰富地球重力场信息为获取地球重力场的时变信息提供可能。本文给出了一种利用LEO星群精密轨道数据反演地球重力场低阶带谐系数时变信息的实用方法——交叠点法，该方法可有效消弱非保守力等因素对重力场反演的影响。然后，以COSMIC (Constellation Observing System for Meteorology Ionosphere & Climate)为实例分析了LEO星群交叠点的覆盖特性，径向轨道精度对交叠点法的影响。最后进行了低阶带谐系数(C20和C30 )时变信号的模拟计算，并对结果进行了分析。

A Crossover Approach to Calculate the Time-variable of the Earth Gravity Field Low Degree Zonal Harmonic Terms Based on LEO Cluster

A crossover point approach was studied for low-cost LEO cluster precise orbit data to recover the global time-variable information without accelerometer system (ACC) or k-band ranging system (KBR) measurements. This approach can reduce the non-gravitational force effects on LEO, obviously. In this paper, we analyzed data coverage and the orbit radial error effect on this approach based on COSMIC (Constellation Observing System for Meteorology Ionosphere & Climate) satellites data. And then, the the low degree zonal harmonic terms, C20 and C30, simulation results of the approach were given.