Ocean mass variations from GRACE and tsunami gauges
Ocean mass variations from GRACE and tsunami gauges
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GRACE 和海啸测量仪的海洋质量变化
DOI：
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发表时间：
2007
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通讯作者：
H. Munekane
中科院分区：
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作者：
H. Munekane
[1]我们将重力恢复和气候实验（GRACE）的质量变化与作为海啸计部署的海底压力记录仪（bpr）测量的质量变化进行了比较。在比较之前，我们利用GPS和GRACE数据，采用1度加载法估计了1度Stokes系数。我们成功地恢复了与卫星激光测距分析和加载模型一致的1度Stokes系数。我们发现，在1度加载方法中使用GRACE数据可以显著减轻未建模的高次加载变形的混叠效应。然后，我们将GRACE的质量变化与作为深海海啸评估和报告（DART）系统一部分部署的五个bpr的质量变化进行了比较。我们观察到除了一个靠近美国大陆的站点外，其他站点的相关性都相当好（超过0.4）。然而，我们发现grace导出的质量变化低估了bpr的近2倍。通过数值模拟，我们发现来自陆地的人工泄漏是造成台站观测到的低相关性的原因，而GRACE处理中的空间平均可能是导致GRACE对bpr质量变化的低估的原因。这些结果说明了在比较grace导出的质量变化与逐点测量结果之前，用数值模型对这些影响进行模拟的重要性。
[1] We compared the mass variations from Gravity Recovery and Climate Experiment (GRACE) with those measured by bottom pressure recorders (BPRs) deployed as tsunami gauges. Prior to the comparison, we estimated the degree-1 Stokes coefficients by the degree-1 loading method using both the GPS and GRACE data. We successfully recovered the degree-1 Stokes coefficients that are consistent with those from the satellite laser ranging analysis and from the loading model. We found that the use of the GRACE data in the degree-1 loading method significantly mitigates the aliasing effect from the unmodeled higher-degree loading deformations. Then, we compared the mass variations from GRACE with those from the five BPRs that have been deployed as part of the Deep-ocean Assessment and Reporting of Tsunamis (DART) system. We observed a fairly good (over 0.4) correlation except for one station that is close to the U.S. mainland. However, we found that the GRACE-derived mass variations underestimate those from BPRs by nearly a factor of 2. Through numerical simulation, we found that the artificial leakage from the landmass is responsible for the low correlation observed at the station, and the spatial averaging in the GRACE processing may be responsible for the underestimation of the mass variations from BPRs by GRACE. These results illustrate the importance of performing a simulation for these effects with numerical models before comparing the GRACE-derived mass variations with those from pointwise measurements.