Observing seasonal steric sea level variations with GRACE and satellite altimetry
Observing seasonal steric sea level variations with GRACE and satellite altimetry
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DOI：
10.1029/2005jc002914
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发表时间：
2006-03-21
影响因子：
3.6
通讯作者：
Chambers, DP
中科院分区：
文献类型：
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作者：
Chambers, DP
[1]海平面随着水柱的温度和盐度的变化而上升和下降，这就是所谓的静止海平面。海平面也会随着水团在海洋中的重新分布或被添加或移除而发生变化。卫星雷达高度计测量这两种影响的组合，而重力恢复和气候实验(GRACE)旨在测量水团运动引起的时变重力。从理论上讲，高度计和GRACE数据可以结合起来计算海平面变化。我们通过结合Current Grace和Jason 1高度计数据并与空间海平面观测进行比较来检验这一点。我们将介绍如何正确组合高度计和GRACE数据，并对需要应用于每种数据类型的重要校正进行注释。利用经验正交函数(EOF)分析，我们检验了季节变化的主导模式，发现GRACE比单独使用测高提高了恢复海平面变化主导模式的能力。在1000公里的平滑半径下，GRACE海洋质量变化的均方根误差估计为海平面的2厘米左右。尽管这比最初从格雷斯任务中预测的要大，但它仍然比在海洋的几个区域恢复的信号小得多。
[1] Sea level rises and falls as the temperature and salinity of the water column varies, which is known as steric sea level. Sea level also changes as water mass is redistributed within the ocean or is added or removed. Satellite radar altimeters measure the combination of both effects, while the Gravity Recovery and Climate Experiment ( GRACE) was designed to measure time variable gravity caused by movement of water mass. Theoretically, altimetry and GRACE data can be combined in order to compute the steric sea level variations. We test this by combining current GRACE and Jason 1 altimeter data and comparing against steric sea level observations. We will describe how to properly combine the altimetry and GRACE data, commenting on important corrections that need to be applied to each data type. Using empirical orthogonal function (EOF) analysis, we examine the leading modes of seasonal variability and find that using GRACE improves the ability to recover the dominant mode of steric sea level variability over using altimetry alone. The RMS error of the GRACE ocean mass variations is estimated to be about 2 cm of sea level at a 1000 km smoothing radius. Although this is larger than initially predicted from the GRACE mission, it is still significantly smaller than the recovered signal in several regions of the ocean.