Ocean and sea ice reanalyses (ORAs or ocean syntheses) are reconstructions of the ocean and sea ice states using an ocean model integration constrained by atmospheric surface forcing and ocean observations via a data assimilation method. Ocean reanalyses are a valuable tool for monitoring and understanding long-term ocean variability at depth, mainly because this part of the ocean is still largely unobserved. Sea surface temperature (SST) is the key variable that drives the air–sea interaction process on different time scales. Despite improvements in model and reanalysis schemes, ocean reanalyses show errors when evaluated with independent observations. The independent evaluation studies of SST from ocean reanalysis over the Indian Ocean are limited. In this study, we evaluated the SST from 10 reanalysis products (ECCO, BRAN, SODA, NCEP-GODAS, GODAS-MOM4p1, ORAS5, CGLORS, GLORYS2V4, GLOSEA, and GREP) and five synthetic observation products (COBE, ERSST, OISST, OSTIA, and HadISST) and from the pure observation-based product AMSR2 for 2012–2017 with 12 in-situ buoy observations (OMNI) over the Arabian Sea and Bay of Bengal. Even though the reanalysis and observational products perform very well in the open ocean, the performance is poorer near the coast and islands. The reanalysis products perform comparatively better than most of the observational products. COBE and OISST perform better among the synthetic observational products in the northern Indian Ocean. GODAS-MOM4p1 and GREP performs best among the reanalysis products, often surpassing the observational products. ECCO shows poorer performance and higher bias in the Bay of Bengal. Comparing the BRAN daily and monthly SST, the monthly SST performance of reanalysis is better than the daily time scale.

中文翻译：

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从北印度洋海洋再分析产品评估海面温度


海洋和海冰再分析（ORA 或海洋合成）是使用受大气表面强迫和海洋观测约束的海洋模型集成通过数据同化方法重建海洋和海冰状态。海洋再分析是监测和了解深处长期海洋变化的宝贵工具，主要是因为这部分海洋在很大程度上仍未被观测到。海面温度 （SST） 是在不同时间尺度上驱动气海相互作用过程的关键变量。尽管模型和再分析方案有所改进，但海洋再分析在用独立观测进行评估时显示出错误。来自印度洋海洋再分析的 SST 独立评估研究是有限的。在这项研究中，我们评估了 10 种再分析产品（ECCO、BRAN、SODA、NCEP-GODAS、GODAS-MOM4p1、ORAS5、CGLORS、GLORYS2V4、GLOSEA 和 GREP）和 5 种合成观测产品（COBE、ERSST、OISST、OSTIA 和 HadISST）的 SST，以及 2012-2017 年基于纯观测的产品 AMSR2，在阿拉伯海和孟加拉湾进行了 12 次原位浮标观测 （OMNI）。尽管再分析和观测产品在开阔海域表现非常好，但在海岸和岛屿附近表现较差。再分析产品的性能相对优于大多数观测产品。COBE 和 OISST 在北印度洋合成观测产品中表现较好。GODAS-MOM4p1 和 GREP 在再分析产品中表现最好，经常超过观察产品。ECCO 在孟加拉湾的表现较差，偏差较高。比较 BRAN 每日和每月 SST，再分析的每月 SST 性能优于每日时间尺度。