球谐分析方法对GRACE大气去混频模型计算的影响

Impact of Spherical Harmonic Analysis Methods on the Computation of GRACE Atmosphere De-Aliasing Models

基于球谐分析的解析积分公式,导出5种适合于大气去混频模型计算的球谐分析公式。采用无误差和加入误差的模拟大气压数据,通过"闭环"过程分析了5种球谐分析方法的正确性和有效性。基于ERA-Interim表面大气压数据,采用5种球谐分析方法计算了5组大气去混频模型。通过星间距离变率残差和累计大地水准面误差比较可知,不同球谐分析方法可导致星间距离变率残差的差距最大达0.6nm/s。第一类Neumann方法精度最高,证明5种球谐分析方法对现有GRACE卫星重力恢复的影响可忽略;但对于未来采用激光测距的卫星重力任务,建议大气去混频模型计算采用第一类Neumann方法。

The quality of atmosphere temporal gravity field models. Impro de-aliasing vement models significantly impact the precision of GRACE atmosphere de-aliasing models will benefit the exact signal extraction of Earth mass changes from GRACE satellites. As spherical harmonic analysis is the main process to convert atmosphere pressure into atmosphere de-aliasing models, this paper deduces five kinds of spherical harmonic analysis formulae that can be adapted to the computation of atmos- phere de-aliasing models based on the analytic integral formulae. Simulated data, with or without white noise, are used to verify the validity and effectiveness of five spherical harmonic analysis methods by closed loop processes. Five atmosphere de-aliasing models are calculated based on the combination of ERA-interim surface pressure data and five spherical harmonic analysis approaches. Using the com- parison of inter-satellite range rate residuals and cumulative geoid height errors, we verify that differ- ent spherical harmonic analysis methods can lead to variability of range rate residuals up to 0.6 nm/s and that the first Neumann method has the highest precision. It can be recognized that the impact of five spherical harmonic analysis methods on the state-of-the-art GRACE satellite gravity field recovery could be negligible, while the first Neumann method is recommended to compute atmosphere de-alias- ing models for future satellite gravity missions with laser ranging measurements.