首页|基于GRACE星间重力位差的Slepian局部地表质量变化反演法

基于GRACE星间重力位差的Slepian局部地表质量变化反演法

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根据Slepian基函数在频域和空域的局部集中特性,建立了利用GRACE星间重力位差(GPD)估计局部地表质量变化的Slepian基函数反演模型及病态问题求解算法,并以亚马逊流域的陆地水储量变化(TWSC)反演为例,评估了反演方法的精度和有效性.首先,通过闭环数值模拟比较了 Slepian基函数法(GPD SBF)、基于GPD的mascon方法(GPD Mascon)和球谐系数法(GPD SH)反演2005年亚马逊流域TWSC的性能,结果表明:Slepian基函数法通过限定信号的频域和空域范围,降低了反演过程中向下延拓带来的不确定性,有效削弱了法方程求解的病态性,其解算结果的稳定性明显优于GPD Mascon;GPD SBF的反演精度及可靠性总体上优于GPD Mascon和GPD SH,并且能够更好地恢复边缘区域的信号和减小泄漏误差的影响.其次,利用实测的GRACE GPD数据反演了2004-2015年亚马逊流域的TWSC时间序列,结果显示:GPD SBF相比GPD Mascon反演的TWSC与官方mascon模型(CSR、JPL和GSFC RL06 mascon)更为一致,并且GPD SBF反演结果呈现出更多的空间细节和更好的信噪比.最后,利用不同GRACE反演结果计算的dS/dt(TWSC的一阶导数)和水文气象数据(GPCP降水、ERA5蒸散发)由水量平衡方程估计了亚马逊流域Obidos水文站的月平均径流量,并采用测站的实测径流量进行检验,结果表明:GPD SBF和GPD Mascon估计的径流量与实测值扣除季节性信号后的差值STD分别为12.35 mm和14.54 mm,相关系数分别为0.71和0.69,并且GPD SBF和各种官方mascon模型估计的径流量与实测径流量更为接近.本文研究证明Slepian基函数法可削弱病态问题求解对正则化约束的依赖,其比传统的GPD Mascon解算精度和可靠性更高,为反演高精度、高分辨率的局部地表质量变化提供了一种新的解决方案.
Slepian inversion method for the recovery of regional surface mass variations based on GRACE intersatellite geopotential differences
According to the regional concentration characteristics of the Slepian basis function in the frequency and spatial domains,we established the Slepian basis function inversion model for recovering regional surface mass variations and the corresponding algorithm for solving the ill-posed problem using GRACE intersatellite geopotential difference(GPD)data.The accuracy and effectiveness of the inversion method had been evaluated through the estimation of terrestrial water storage change(TWSC)in the Amazon River basin.Firstly,the performance of the Slepian basis function method(GPD SBF),GPD-based mascon method(GPD Mascon),and GPD-based spherical harmonic method(GPD SH)for recovering the TWSC over the Amazon River basin in 2005 had been investigated through a closed-loop simulation study.The results demonstrate that the GPD SBF reduces the uncertainty caused by downward continuation in the inversion process by limiting the frequency and spatial domains of the signals,and effectively weakens the degree of ill-posed problem for solving the normal equations,and the stability of the solutions estimated by GPD SBF is significantly better than that of GPD Mascon.Furthermore,the accuracy and reliability of GPD SBF solutions are generally better than those of GPD Mascon solutions and GPD SH solutions,and GPD SBF can better recover the TWSC signal in edge regions and effectively reduce the leakage error.Secondly,the TWSC time series of the Amazon River basin were estimated by the measured GRACE GPD data from 2004 to 2015.The results indicate that the TWSC time series estimated by GPD SBF are more consistent with the official mascon solutions(CSR,JPL and GSFC RL06 mascon)than those estimated by GPD Mascon,and the GPD SBF solutions present more spatial details and better signal-to-noise ratio compared with the GPD Mascon solutions.Finally,using the hydrometeorological data(GPCP precipitation and ERA5 evapotranspiration)and the dS/dt(first derivative of TWSC)series derived from different GRACE solutions,the monthly averaged runoff time series at the Obidos hydrological station in the Amazon River basin were estimated through the water balance equation,and the runoff estimates were verified through in-situ runoff measurements.The results show that the residual standard deviations between the time series of estimated runoff and in-situ runoff with seasonal components removed are 12.35 mm and 14.54 mm for GPD SBF and GPD Mascon,and the corresponding correlation coefficients are 0.71 and 0.69,respectively.Moreover,the runoff estimates from the GPD SBF solutions and official mascon solutions are closer to the in-situ runoff measurements.This study demonstrates that the GPD SBF can weaken the dependence on regularization constraints for solving the ill-posed problem,and GPD SBF solutions have higher accuracy and reliability than the traditional GPD Mascon solutions,which provides a new solution strategy for estimation of high-precision and high-resolution regional surface mass variations.

Regional surface mass variationsSlepian basis functionIntersatellite geopotential differencesTikhonov regularizationGRACEAmazon River basin

钟波、谭江涛、李贤炮、李建成、李琼

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武汉大学测绘学院,武汉 430079

湖北珞珈实验室,武汉 430079

地球空间环境与大地测量教育部重点实验室,武汉 430079

西南石油大学土木工程与测绘学院,成都 610500

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局部地表质量变化 Slepian基函数 星间重力位差 Tikhonov正则化 GRACE 亚马逊流域

国家自然科学基金项目国家自然科学基金项目国家自然科学基金项目湖北珞珈实验室专项基金资助项目

423881024237400241974015220100004

2024

10.6038/cjg2023Q0970

地球物理学报
中国地球物理学会 中国科学院地质与地球物理研究所

地球物理学报

CSTPCD北大核心
影响因子：3.703
ISSN：0001-5733
年,卷(期)：2024.67(7)
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