Ocean mesoscale structure–induced air–sea interaction in a high-resolution coupled model

Using the Community Earth System Model framework, the authors build a very-high-resolution quasi-global coupled model by coupling an eddy-resolving quasi-global ocean model with a high-resolution atmospheric model. The model is successfully run for six years under present climate conditions, and the simulations are evaluated against observational and reanalysis data.The model is capable of simulating large-scale oceanic and atmospheric circulation patterns, sea surface temperature(SST) fronts, oceanic eddy kinetic energy, and fine-scale structures of surface winds. The ocean mesoscale structure–induced air–sea interaction characteristics are explored in detail. The model can effectively reproduce positive correlations between SST and surface wind stress induced by mesoscale structures through comparison with observations. The positive correlation is particularly significant over regions with strong oceanic fronts and eddies.However, the responses of wind stress to eddy-induced SST are weaker in the simulation than in the observations, although different magnitudes exist in different areas. Associated with weak wind responses, surface sensible heat flux responses to eddy-induced SST are underestimated slightly, while surface latent heat flux responses are overestimated because of the drier atmospheric boundary layers in the model. Both momentum mixing and pressure adjustment mechanisms play important roles in surface wind changes over oceanic fronts and eddies in the high-resolution model.

本文基于通用地球系统模式框架,建立了一个非常高分辨率准全球的耦合模式,其分量为涡分辨率海洋模式和高分辨率大气模式。利用这个模式,在现代气候条件下成功进行6年的试验,并根据高分辨率观测和再分析资料评估了试验结果。这个模式能够模拟大尺度大气海洋结构,海表面温度(SST)锋面,海洋涡旋动能,和风的细致结构。据此,仔细研究了海洋中尺度结构引起的海气相互作用特征。通过对比观测,这个模式很好再现了由中尺度结构引起的SST和风应力的正相关。同时,正相关在强海洋锋面和涡旋区域特别明显。在模拟中,风对中尺度扰动引起的SST的响应偏弱,但不同区域响应量值略有不同。伴随着风的响应偏弱,表面感热的响应被低估,而潜热的响应则被高估,高估原因是因为模式的边界层偏干。风对SST中尺度异常响应主要来自动量垂直混合和气压调整的综合作用。本研究对于中尺度海气相互作用的模拟提供了一些新的线索及对模式的改进提供科学依据。