Meridional position biases of East Asian subtropical jet stream in CMIP5 models and their relationship with ocean model resolutions
Meridional position biases of East Asian subtropical jet stream in CMIP5 models and their relationship with ocean model resolutions
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DOI：
10.1002/joc.4256
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发表时间：
2015-11
期刊：
影响因子：
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通讯作者：
Jing Ma;Haiming Xu;P. Lin
中科院分区：
文献类型：
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作者：
Jing Ma;Haiming Xu;P. Lin
利用欧洲中期天气预报中心（ECMWF）的ERA - interim再分析资料评估了耦合模式比较计划第5阶段（CMIP5）中20个模式模拟的东亚副热带急流（EASJ）。多模式集合平均（MME）对EASJ的气候态模拟较为合理；然而，与观测相比，MME的EASJ在所有季节均向南偏移。进一步研究发现，只有在海洋模式分辨率相对较粗的耦合大气环流模式（CGCMs）中，模拟的EASJ在四个季节均显著向南偏移；对于那些海洋模式分辨率相对较高的CGCMs，模拟的EASJ向北偏移，这表明EASJ模拟的经向位置与海洋模式的水平分辨率密切相关。基于奇异值分解（SVD）和合成分析，EASJ模拟的经向位置与黑潮 - 亲潮延伸区（KOE）的海表温度（SST）密切相关，EASJ向南（向北）偏移对应着较低（较高）的SST。海洋模式分辨率相对较低（较高）的CGCMs通常模拟出KOE区域的负（正）SST偏差，与MME相比，SST分别降低（升高）约 - 3K（ + 2K）。通过混合层热收支分析表明，海洋模式分辨率粗、细不同的模式之间的SST差异主要归因于海洋热输送效应。
The East Asian subtropical jet (EASJ) stream in each of the 20 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) is evaluated against the ERA‐interim product. The multi‐model ensemble mean (MME) simulates a reasonably realistic climatology of the EASJ; however, the MME EASJs are shifted southward in all seasons in comparison with the observations. Upon closer inspection, it is found that only in the coupled general circulation models (CGCMs) with relatively coarse ocean model resolutions are the simulated EASJs shifted southward remarkably in all four seasons; for those CGCMs with relatively high ocean model resolutions, the simulated EASJs are shifted northward, indicating that the simulated meridional location of the EASJ is closely related to the horizontal resolution in the ocean model. Based on the singular value decomposition (SVD) and composite analyses, the simulated meridional location of the EASJ is closely associated with the sea surface temperature (SST) over the Kuroshio–Oyashio Extension (KOE) region, with southward (northward) shift of the EASJ corresponding to low (high) SSTs. The CGCMs with relatively low (high) ocean model resolutions generally simulate negative (positive) SST biases over the KOE region with an SST decrease (increase) of about −3 K (+2 K) in comparison with the MME. Through a mixed‐layer heat budget analysis, it is revealed that the SST differences between the models with coarse and fine ocean components are mainly attributed to the ocean heat transport effect.