Comparison of GRACE and GNSS seasonal load displacements considering regional averages and discrete points.
Comparison of GRACE and GNSS seasonal load displacements considering regional averages and discrete points.
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考虑区域平均值和离散点的 GRACE 和 GNSS 季节性荷载位移比较。
DOI：
10.1029/2021jb021775
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Wenke Sun
中科院分区：
文献类型：
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作者：
Lan Zhang;He Tang;Wenke Sun
全球导航卫星系统（GNSS）和重力恢复与气候实验（GRACE）是两种独立的大地测量技术，分别可以检测几何变形和重力变形。两种技术观测到的信号主要包括内部构造运动和地表质量载荷效应。前者总体呈现长期稳定的线性趋势，而后者则表现出较强的季节性。许多研究比较了 GRACE 和 GNSS 之间的季节性变形，或将它们结合起来研究水循环或构造信号。然而，GRACE 和 GNSS 是否具有可比性以及它们之间的差异有多大仍不清楚。在这项研究中，我们提出了亚马逊盆地的模拟和案例研究来解决这一模糊性。响应不同分辨率和分布的载荷质量来模拟载荷变形。我们发现，由于单个载荷质量，应用 G300 或 DDK4 滤波器后，精确载荷位移与 60 度截断结果之间的空间平均值差异约为 30%。模拟的水平变形可能在响应棋盘质量分布的单点处具有较大差异。亚马逊流域的案例研究基本验证了我们的模拟结果，表明GNSS观测的位移空间平均值与GRACE模型的位移空间平均值之间存在~40%~50%的差异，并且在单点上可能达到数倍。我们证明 GRACE 和 GNSS 之间的差异对于区域平均和单点分析都很显着。
The global navigation satellite system (GNSS) and gravity recovery and climate experiment (GRACE) are two independent geodetic technologies that can detect geometric and gravity deformations, respectively. The signals observed by the two technologies mainly include the internal tectonic movement and surface mass loading effects. The former generally exhibits a long‐term stable linear trend, whereas the latter exhibits strong seasonality. Many studies have compared seasonal deformations between GRACE and GNSS or combined them to study the water cycle or tectonic signals. However, whether GRACE and GNSS are comparable and what the magnitude of their differences still remain unclear. In this study, we present simulations and a case study of the Amazon basin to address this ambiguity. The loading deformations were simulated in response to load masses with varying resolutions and distributions. We found that the discrepancy is about 30% in the spatial average between the accurate loading displacement and the truncated‐result at degree‐60 after applying a G300 or DDK4 filter due to a single load mass. The simulated horizontal deformation may have larger discrepancies at a single point in response to the chessboard mass distributions. The case study in the Amazon basin basically verifies our simulation results, which indicate that there is an ∼40%–50% discrepancy between the GNSS‐observed and GRACE‐modeled displacements spatial average, and it may reach several times that at a single point. We demonstrate that the difference between the GRACE and GNSS is significant for both regional average and single‐point analyses.