冬季北太平洋海表热通量异常和海气相互作用——基于一个全球海气耦合模式长期积分的诊断分析

Wintertime North Pacific Surface Heat Flux Anomaly and Air-Sea Interaction in a Coupled Ocean-Atmosphere Model

利用一个全球海气耦合模式长期积分所给出的资料，分析了冬季北太平洋海表湍流热通量（潜热和感热）异常及其对海表温度（ＳＳＴ）异常的影响，并比较了海表热通量诸分量和海洋内部的动力学过程对ＳＳＴ变化的相对重要性。结果表明，冬季热带外海洋上的湍流热通量是影响ＳＳＴ的主要因子，但在北太平洋中部海水的平流作用也不可忽视。冬季热带外海洋向大气释放的潜热和感热通量与ＳＳＴ倾向（而不是ＳＳＴ本身）之间存在着显著的相关，这同Ｃａｙａｎ和Ｒｅｙｎｏｌｄｓ等利用ＣＯＡＤＳ资料和ＮＣＥＰ资料同化模式分析的结果是一致的。模式诊断的结果支持这样一种看法：和热带海洋不同，冬季热带外海洋上的海气相互作用主要地表现为大气对海洋的强迫作用，而不是相反。模式给出的ＳＳＴ倾向的第一个ＥＯＦ分量及其与海平面气压场的相关特征同Ｗａｌａｃｅ等从观测资料分析所得到的结果是一致的；进一步的分析表明：在冬季北太平洋的大部分区域（特别是西太平洋），大尺度大气环流异常在很大程度上决定着ＳＳＴ的异常，而这种决定作用正是通过它对湍流热通量的强烈影响来实现的。

The anomalous sea surface turbulent heat fluxes (sensible and latent) and their impact on the SST anomaly in the North Pacific during winters are analyzed based on the data extracted from a long-term integration of a coupled ocean-atmosphere general circulation model A comparison of the relative importance of various heat flux components and other terms related to the ocean dynamics in determining the SST tendency shows that the turbulent heat fluxes have major contributions to the SST tendency in most of the extratropical North Pacific Ocean with an exception in a central area of the basin where the contribution from the horizontal advection of SST may not be negligible The modeled latent and sensible heat flux anomalies are correlated strongly to the SST tendency anomaly rather than the SST anomaly itself in the extratropical ocean during winters, which is in agreement with the observational analyses of both Cayan based on the COADS data and Reynolds et al based on the NCEP data assimilation system The model's performance supports such an notion that the atmospheric forcing of the ocean rather than vise versa is dominant in the air-sea interaction over the wintertime extratropical ocean, which is obviously different from the situation in the tropical ocean The modeled first EOF mode of the SST tendency and its correlation with the sea level pressure, as a representative variable of the large-scale atmospheric circulation pattern, are rather similar to those given by Wallace et al in their observational analysis A further analysis shows that the anomalous large-scale atmospheric circulation that determines, to a great degree, the SST anomalies through affecting strongly the turbulent heat fluxes in most of the extratropical North Pacific, particularly in the western Pacific