Estimated accuracies of regional water storage variations inferred from the Gravity Recovery and Climate Experiment (GRACE)
Estimated accuracies of regional water storage variations inferred from the Gravity Recovery and Climate Experiment (GRACE)
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DOI：
10.1029/2002wr001808
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发表时间：
2003-08
影响因子：
5.4
通讯作者：
S. Swenson;J. Wahr;P. Milly
中科院分区：
文献类型：
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作者：
S. Swenson;J. Wahr;P. Milly
卫星重力恢复和气候实验(GRACE)提供了描述大地水准面月度变化的数据，这些数据与垂直整合的陆地水储存的变化密切相关。与传统的点状或网格状水文测量不同，GRACE数据是大地水准面截断球面调和展开中的斯托克斯系数集。Swenson和Wahr[2002]描述了构造空间平均核的技术，利用该核，可以从一组斯托克斯系数中提取给定区域内垂直综合储水量的平均变化。这项研究通过将平均核应用于部分来自大规模水文模型的真实合成GRACE重力信号来扩展这项工作。通过将从合成GRACE数据推断的蓄水量估计值与同一水文模型预测的蓄水量估计值进行比较，我们能够评估GRACE估计值的准确性，并比较不同平均核函数的性能。我们特别专注于恢复北美河流流域内每月的储水量变化。我们的结论是，对于面积为4.0·105平方公里或更大的地区，GRACE将能够估计每月蓄水量的变化，其精度优于1厘米的水厚。对于较大的区域，精度更高。例如，密西西比河流域(面积=3.9·106平方公里)的蓄水信号可以得到优于5 mm的信号。对于区域到全球尺度的水平衡分析，这一结果表明，GRACE将为流域水平衡分析提供有用的、直接的季节性蓄水量测量；这种数据在水文分析中是前所未有的。
The satellite Gravity Recovery and Climate Experiment (GRACE) provides data describing monthly changes in the geoid, which are closely related to changes in vertically integrated terrestrial water storage. Unlike conventional point or gridded hydrologic measurements, such as those from rain gauges, stream gauges, rain radars, and radiometric satellite images, GRACE data are sets of Stokes coefficients in a truncated spherical harmonic expansion of the geoid. Swenson and Wahr [2002] describe techniques for constructing spatial averaging kernels, with which the average change in vertically integrated water storage within a given region can be extracted from a set of Stokes coefficients. This study extends that work by applying averaging kernels to a realistic synthetic GRACE gravity signal derived in part from a large‐scale hydrologic model. By comparing the water storage estimates inferred from the synthetic GRACE data with the water storage estimates predicted by the same hydrologic model, we are able to assess the accuracy of the GRACE estimates and to compare the performance of different averaging kernels. We focus specifically on recovering monthly water storage variations within North American river basins. We conclude that GRACE will be capable of estimating monthly changes in water storage to accuracies of better than 1 cm of water thickness for regions having areas of 4.0 · 105 km2 or larger. Accuracies are better for larger regions. The water storage signal of the Mississippi river basin (area = 3.9 · 106 km2), for example, can be obtained to better than 5 mm. For regional‐ to global‐scale water balance analyses, this result indicates that GRACE will provide a useful, direct measure of seasonal water storage for river‐basin water balance analyses; such data are without precedent in hydrologic analysis.