Assessment of GRACE/GRACE Follow-On Terrestrial Water Storage Estimates Using an Improved Forward Modeling Method: A Case Study in Africa
Assessment of GRACE/GRACE Follow-On Terrestrial Water Storage Estimates Using an Improved Forward Modeling Method: A Case Study in Africa
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DOI：
10.3389/feart.2021.796723
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发表时间：
2022-02
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影响因子：
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通讯作者：
Hao Zhou;Mingyu Dai;Penghui Wang;Minxue Wei;Lu Tang;Siyou Xu;Zhicai Luo
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作者：
Hao Zhou;Mingyu Dai;Penghui Wang;Minxue Wei;Lu Tang;Siyou Xu;Zhicai Luo
来自空间滤波器的泄漏误差是通过重力恢复和气候实验（GRACE）使命和最近发射的GRACE后续使命估计陆地水储存的主要限制。在这里，我们开发了一种改进的正演模拟方法，并评估其性能，减少泄漏误差在非洲。在无噪声条件下，正演方法在恢复信号方面表现出了较好的性能，改进的正演方法可以进一步减小沿着非洲海岸线的泄漏误差。在噪声污染条件下，GRACE使命和GRACE后续使命的模拟环境尽可能地设置为真实的。基于GRACE和GRACE Follow-On解的模拟结果表明，改进的正演模拟方法在减小泄漏误差方面具有较好的效果。在模拟GRACE数据的情况下，非洲24个流域的平均改善分别为37%的年振幅和36%的趋势。与这些模拟GRACE数据相比，通过模拟GRACE后续解决方案的改善是轻微的大中型流域，但他们是显着的小流域。在模拟GRACE后续解决方案的情况下，非洲的年振幅平均改善39%，趋势平均改善41%。最后，利用改进的正演方法对空间研究中心（CSR）的GRACE球谐数据集进行了处理。结果提出了更好的协议与来自新发布的mascon解决方案从喷气推进实验室（JPL）和CSR相比，来自CSR的Tellus网格的比例因子。这些模型无关的方法之间的良好的一致性表明，我们改进的正演模拟方法的良好性能和进一步的必要性，仔细评估模型依赖的方法时，使用不同的先验水文模型。基于无噪声观测、噪声污染观测和GRACE数据集的实验表明，改进的正演方法能够恢复时间信号。
Leakage errors derived from spatial filters are the major limitation for estimating terrestrial water storage via the Gravity Recovery and Climate Experiment (GRACE) mission and the recently launched GRACE Follow-On mission. Here we develop an improved forward modeling method and assess its performance of reducing leakage errors over Africa. In noise-free condition, the forward modeling method shows its outperformance in restoring signals, and the improved forward modeling method can further reduce the leakage errors along the coastline of Africa. In noise-contaminated condition, the simulated environment is set as real as possible to GRACE mission and GRACE Follow-On mission. The results based on the simulated GRACE and GRACE Follow-On solutions demonstrate the capacity of improved forward modeling method in reducing leakage errors. In the case of simulated GRACE data, the average improvements of 24 basins over Africa are respectively 37% for annual amplitudes and 36% for trends. When compared with these simulated GRACE data, the improvements via simulated GRACE Follow-On solutions are minor over large and medium size river basins, but they are significant over small size river basins. In the case of simulated GRACE Follow-On solutions, the average improvements over Africa are 39% for annual amplitudes and 41% for trends. Eventually, the improved forward modeling method is used to process GRACE spherical harmonic datasets from the Center for Space Research (CSR). The results present better agreement with those derived from the newly released mascon solutions from Jet Propulsion Laboratory (JPL) and CSR, when compared with those derived from CSR Tellus grids with scale factors. The better consistency between these model-independent approaches indicates the good performance of our improved forward modeling method and the further necessity of careful evaluation of model-dependent approaches when using different prior hydrological models. Overall, experiments based on noise-free observations, noise-contaminated observations, and GRACE datasets indicate that improved forward modeling method is capable of restoring temporal signals.