The Inversion of Terrestrial Water Storage Changes by Non-isotropic Combination Filter

doi:10.11947/j.AGCS.2015.20130719

Abstract

Abstract: The inversion of variations of terrestrial water storage by the earth time-variable gravity filed model makes a great contribution to global climate change, however, the spherical harmonics of time-variable gravity field have correlation problem and significant errors in high orders and degrees, and so optimal filtering method is needed to solve this problem. In this article, a new filter was devised named‘non-isotropic combination filter’, and showed a better performance. The basic idea of the new filter is to apply the Gaussian filter and the RMS filter to low-degree and high-degree harmonic coefficients separately. In this paper, we first analyze the error characteristics of the latest GRACE RL05 series variable gravity field model, compare the validity and precision with Gaussian filter, improved Gaussian filter, RMS filter, DDK filter, the non-isotropic combination filter and verified them with the model. It shows that the mean square error of the non-isotropic combination filter and model is the least. Based on above analysis, we find that the non-isotropic combination filter can suppress the noises in high-degrees and high-orders, eliminate the N-S striping errors, lower signal leakage errors, improve the ratio of signal-to-noise more effectively compared with the previous filters.

Key words: GRACE, spherical harmonics, time-variable gravity field, filter

CLC Number:

P223

CHAO Nengfang, WANG Zhengtao, SUN Jian. The Inversion of Terrestrial Water Storage Changes by Non-isotropic Combination Filter[J]. Acta Geodaetica et Cartographica Sinica, 2015, 44(2): 174-182.

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