Impacts of Argo salinity in NCEP Global Ocean Data Assimilation System: The tropical Indian Ocean
Impacts of Argo salinity in NCEP Global Ocean Data Assimilation System: The tropical Indian Ocean
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DOI：
10.1029/2007jc004388
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发表时间：
2008-08
影响因子：
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通讯作者：
Boyin Huang;Y. Xue;D. Behringer
中科院分区：
文献类型：
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作者：
Boyin Huang;Y. Xue;D. Behringer
自2000年以来，国际Argo项目（国际Argo项目数据可在http://argo.jcommops.org上获得）收集的盐度剖面为我们提供了一个前所未有的机会来研究盐度数据对海洋分析质量的影响，这在历史上一直受到缺乏盐度观测的阻碍。由美国国家环境预测中心（NCEP）开发的全球海洋资料同化系统（GODAS）可同化由温度和当地T-S气气学构建的温度和合成盐度剖面。在这项研究中，我们评估了用Argo盐度代替合成盐度对GODAS海洋分析质量的影响，重点是热带印度洋。这项研究基于2001-2006年的两项全球海洋分析，其中包括（NCEP_Argo）和不包括（NCEP_Std）的Argo盐度。海洋分析的质量是通过与各种独立观测数据进行比较来估计的，如漂浮物的表面流数据、三角跨洋浮标网系泊的盐度数据以及卫星高度计的海面高度（SSH）数据。我们发现，通过吸收Argo盐度，盐度分析中的偏差在热带印度洋东部减少了0.6个实际盐度单位（psu），在孟加拉湾减少了1个psu。与这些盐度变化相关，冬季赤道印度洋中部的纬向流向东增加了30-40 cm s - 1。通过对漂流的验证，热带印度洋年平均纬向流的偏置减小了5 ~ 10 cm s−1，表面纬向流的均方根误差减小了2 ~ 5 cm s−1。在热带印度洋、孟加拉湾和阿拉伯海，侧向偏压减小了3厘米。这些结果表明，Argo盐度在改善盐度分析中起着关键作用，进而有助于改善表面流和海面高度分析。
[1] Salinity profiles collected by the International Argo Project (International Argo Project data are available at http://argo.jcommops.org) since 2000 provide us an unprecedented opportunity to study impacts of salinity data on the quality of ocean analysis, which has been hampered by a lack of salinity observations historically. The operational Global Ocean Data Assimilation System (GODAS) developed at the National Centers for Environmental Prediction (NCEP) assimilates temperature and synthetic salinity profiles that were constructed from temperature and a local T-S climatology. In this study, we assess impacts of replacing synthetic salinity by Argo salinity on the quality of the GODAS ocean analysis with a focus on the tropical Indian Ocean. The study was based on two global ocean analyses for 2001–2006 with (NCEP_Argo) and without (NCEP_Std) inclusion of Argo salinity. The quality of the ocean analyses was estimated by comparing them with various independent observations such as the surface current data from drifters, the salinity data from the Triangle Trans-Ocean Buoy Network moorings, and the sea surface height (SSH) data from satellite altimeters. We found that by assimilating Argo salinity, the biases in the salinity analysis were reduced by 0.6 practical salinity units (psu) in the eastern tropical Indian Ocean and by 1 psu in the Bay of Bengal. Associated with these salinity changes, the zonal current increased by 30–40 cm s−1 toward the east in the central equatorial Indian Ocean during the winter seasons. When verified against drifter currents, the biases of the annually averaged zonal current in the tropical Indian Ocean were reduced by 5–10 cm s−1, and the root-mean-square error of surface zonal current was reduced by 2–5 cm s−1. The SSH biases were reduced by 3 cm in the tropical Indian Ocean, the Bay of Bengal, and the Arabian Sea. These results suggest that the Argo salinity plays a critical role in improving salinity analysis, which in turn contributed to improved surface current and sea surface height analyses.