GOCE实测数据反演高阶重力场模型的Torus方法

不同于当前广泛使用的空域法、时域法、直接解法,本文尝试采用Torus方法处理GOCE实测数据,利用71 d的GOCE卫星引力梯度数据反演了200阶次GOCE地球重力场模型,实现了对参考模型的精化。首先,采用Butterworth零相移滤波方法加移去—恢复技术,处理引力梯度观测值中的有色噪声,并利用泰勒级数展开和Kriging方法对GOCE卫星引力梯度数据进行归算和格网化,计算得到了名义轨道上格网点处的引力梯度数据。然后,利用2D-FFT技术和块对角最小二乘方法处理名义轨道上数据,获得了200阶次的GOCE地球重力场模型GOCE_Torus。利用中国和美国的GPS/水准数据进行外部检核结果说明,GOCE_Torus与ESA发布的同期模型的精度相当;GOCE_Torus模型与200阶次的EGM2008模型相比,在美国区域精度相当,但在中国区域精度提高了4.6 cm,这充分体现了GOCE卫星观测数据对地面重力稀疏区的贡献。Torus方法拥有快速高精度反演卫星重力场模型的优势,可以在重力梯度卫星的设计、误差分析及在轨快速评估等方面得到充分应用。

Torus approach in high degree gravity field model determination from GOCE satellite gradiometry observations

Currently, space-wise method, time-wise method and direct-wise method are widely used to deal with the GOCE satellite real observations. Different from these conventional methods, this paper proposes one Torus approach. As one refinement of the reference model, the GOCE earth gravity field model complete to 200 d/o is recovered using 71-day GOCE satellite gradiometry observations with Torus approach. Firstly, a Butterworth filter with zero-phase combining with remove-restore is used to deal with the colored noise in GOCE satellite gravitational gradient observations. These observations are reduced from the real orbits to nominal orbits using Taylor series expansion and Kriging is used for gridding on the nominal orbits. Then, 2D-FFT and the block-diagonal least-square adjustment are performed to process the gridded observations, so that the GOCE earth gravity field model complete to 200 d/o named as GOCE_Torus can be realized efficiently. GOCE_Torus is assessed with the GPS/leveling data in China and USA, respectively. GOCE_Torus and the first generation model released by ESA have a similar accuracy. In USA, EGM2008 complete to 200 d/o reveals a similar accuracy with GOCE_Torus. But in China, GOCE_Torus is improved by 4.6 cm due to the contribution of GOCE gravity gradiometry data. With the application of Torus approach the satellite gravity field model can be recovered quickly and accurately, and therefore this approach is useful in mission design, error analysis and in-orbit evaluation of gravity gradient satellites.