Comparative analysis of Green's functions and Slepian basis functions for GNSS inversion of terrestrial water

doi:10.11947/j.AGCS.2023.20220624

Abstract

Abstract: Terrestrial water storage is an important part of water resources. Changes in terrestrial water storage are related to the development of human society. Atmospheric warming has a profound impact on the distribution of global terrestrial water storage, and even worsens the relationship between regional water supply and demand. With the construction of continuous GNSS station network in China, GNSS has become a new type of geodetic method for monitoring terrestrial water storage changes. At present, the methods for terrestrial water inversion using continuous GNSS stations are mainly divided into Green's function and Slepian basis function inversion methods, but there are few reports on the differences and applicable scenarios of those two methods. Starting from the basic principles of the two methods, this paper uses simulated data and measured GNSS data to perform inversion based on the Green's function and the Slepian basis function, respectively. Results show that: ① Based on the simulation data, the number and spatial distribution of GNSS stations are different, and the Green's function inversion results are more affected than the Slepian basis function inversion results. The overall accuracy of Green's function inversion results is better, and the Slepian basis function method is greatly affected by the maximum truncation order. ② Based on the real “land-state network” and the vertical time series data of GNSS continuous observation stations of the Meteorological Bureau, the correlation between the two methods to retrieve the equivalent water height is 0.98, and the amplitude of the Slepian basis function inversion result is 25% larger than that of the Green function inversion result on average. ③ The results of GNSS inversion and the terrestrial water phase inferred by GRACE and GLDAS are all greater than 0.65, and the monthly precipitation data are in good agreement. The peak of the equivalent water height sequence retrieved by GNSS lags behind the maximum rainfall by 1~2 months. Considered the reality in most area of China, the density GNSS stations is not enough for the application for Green's method in TWS inversion, so the Slepian method is the good choice.

Key words: GNSS, Green's function, Slepian basis function, terrestrial water storage, equivalent water height

CLC Number:

P227

CHEN Chao, ZOU Rong, CAO Jiaming, LI Yu, LIANG Hong, FANG Zhiwei. Comparative analysis of Green's functions and Slepian basis functions for GNSS inversion of terrestrial water[J]. Acta Geodaetica et Cartographica Sinica, 2023, 52(12): 2066-2077.

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