Sea level budget in the Bay of Bengal (2002–2014) from GRACE and altimetry
Sea level budget in the Bay of Bengal (2002–2014) from GRACE and altimetry
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DOI：
10.1002/2015jc011471
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发表时间：
2016-02
影响因子：
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通讯作者：
J. Kusche;B. Uebbing;R. Rietbroek;C. Shum;Z. Khan
中科院分区：
文献类型：
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作者：
J. Kusche;B. Uebbing;R. Rietbroek;C. Shum;Z. Khan
海平面上升被认为是对孟加拉湾人口稠密的海岸的主要威胁。应对未来的上升需要了解目前的海平面预算。使用一种新的方法和重力恢复和气候实验（GRACE）卫星的数据，我们将高度海平面上升（2002-2014年为6.1 mm/a）划分为质量和空间分量。我们发现，孟加拉湾目前的质量趋势略高于全球平均水平，而空间趋势似乎大得多：2.2-3.1毫米/年，如果我们忽略所需的剩余关闭预算，和4.3-4.6毫米/年，如果作为上限，我们把这个剩余完全空间扩张。我们的方法不同于已发表的方法，因为它解释了测高和GRACE数据在最小二乘反演，而质量异常通过重力自洽指纹参数化，并通过EOFs空间膨胀。我们验证我们的估计，通过比较Argo和建模印度洋，并通过比较恒河和雅鲁藏布江流域的总蓄水量变化（TWSC）的传统GRACE方法。我们发现很好的协议TWSC，和合理的协议的立体高度，取决于海洋区域和Argo产品。我们将差异归因于Argo数据的弱点，但我们也发现反演在一定程度上对EOFs敏感。最后，结合我们的估计与CMIP 5模拟，我们估计孟加拉湾绝对海平面可能会上升额外的37厘米下的RCP4.5的情况下，40厘米下的RCP8.5，直到2050年，相对于2005年。
Sea level rise is perceived as a major threat to the densely populated coast of the Bay of Bengal. Addressing future rise requires understanding the present-day sea level budget. Using a novel method and data from the Gravity Recovery and Climate Experiment (GRACE) satellite, we partition altimetric sea level rise (6.1 mm/a over 2002–2014) into mass and steric components. We find that current mass trends in the Bay of Bengal are slightly above global mean, while steric trends appear much larger: 2.2–3.1 mm/a if we disregard a residual required to close the budget, and 4.3–4.6 mm/a if, as an upper bound, we attribute this residual entirely to steric expansion. Our method differs from published approaches in that it explains altimetry and GRACE data in a least squares inversion, while mass anomalies are parameterized through gravitationally self-consistent fingerprints, and steric expansion through EOFs. We validate our estimates by comparing to Argo and modeling for the Indian Ocean, and by comparing total water storage change (TWSC) for the Ganges and Brahmaputra basins to the conventional GRACE approach. We find good agreement for TWSC, and reasonable agreement for steric heights, depending on the ocean region and Argo product. We ascribe differences to weaknesses of the Argo data, but we also find the inversion to be to some extent sensitive with respect to the EOFs. Finally, combining our estimates with CMIP5-simulations, we estimate that Bay of Bengal absolute sea level may rise for additional 37 cm under the RCP4.5 scenario and 40 cm under RCP8.5 until 2050, with respect to 2005.