GRACE RL05反演南极冰盖质量变化方法比较

Comparison of Several Filters in the Rates of Antarctic Ice Sheet Mass Change Based on GRACE RL05 Data

  • 摘要: 利用UTCSR发布的2003-01~2013-07GRACE RL05月平均重力场模型,分析比较了高斯滤波、各向异性滤波、扇形滤波和维纳滤波,并结合去相关滤波在反演南极地区冰盖质量变化方面的差异。通过计算得到以下结论:①基于121组重力场模型阶方差分布得到维纳滤波与半径为300 km的高斯滤波效果最为接近,说明300 km滤波半径完全可以满足质量变化信号的提取;②在一定范围内,提高滤波半径能提高反演结果信噪比,建议南极区域的滤波半径为500 km;采用相同滤波半径,不同空间滤波算法计算的质量变化率基本一致,在南极区域可以选取任一滤波方法;③与其他算法相比,去相关滤波算法能在一定程度消除球谐系数中存在的系统误差,改善反演结果。

     

    Abstract: Time-variable series of earth gravity model are obtained by means of GRACE, which can be continuously monitor variations of the mass in or on the surface of the Antarctic ice sheet in middle and large scales. Gravity solutions of GRACE RL05 from January 2003 to July 2013 released by UTCSR are used in this paper. Several filters, such as isotropic Gauss, non-isotropic, Fan, Wiener and de-correlated filter, were compared in the inversion of the Antarctic ice sheet mass change rates. Through analysis and comparison, the following conclusions are obtained: (1) The signal and noise function of Wiener were calculated by 121 months gravity model and the result was very close to that of the Gaussian smoothing radius of 300 km, and that is mass change can be completely extracted by using the 300km radius of filtering; (2) Increasing the radius of the filter is an effective way to improve the accuracy of the results, so the propositional radius of filtering in the Antarctic area can be 500km; With the same filter radius, the rates of mass changed are basically consistent for different methods; (3) De-correlated filter is more effective method in reducing the systematic errors of spherical harmonic coefficient. The conclusions as above help reconcile CRACE ice mass estimates obtained for different filter strategies.

     

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