Rossby wave dynamics of the North Pacific extra-tropical response to El Niño: importance of the basic state in coupled GCMs
Rossby wave dynamics of the North Pacific extra-tropical response to El Niño: importance of the basic state in coupled GCMs
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北太平洋温带对厄尔尼诺现象响应的罗斯贝波动力学：耦合 GCM 中基本态的重要性
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
D. Stevens
中科院分区：
文献类型：
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作者：
Andrew Dawson;A. Matthews;D. Stevens
政府间气候变化专门委员会第四次评估报告模拟中典型的“低”水平分辨率耦合气候模式对厄尔尼诺现象的热带外反应显示出严重的系统误差。同一模型的高分辨率配置具有与观测相似的大大改进的响应。低分辨率模式中的误差可以追溯到厄尔尼诺期间控制热带外海面温度（SST）的大气遥相关机制的不正确表示。这是由于不切实际的大气平均状态，它改变了Rossby波的传播特性。这些错误的上层对流层环流异常，然后导致错误的地面环流特征在北太平洋。相关的地面风速和风向误差产生了错误的地面通量和上升流异常，最终导致低分辨率模式中不正确的热带外SST对厄尔尼诺的响应。这突出表明气候反应对复杂气候过程链中的一个环节的敏感性。这些过程在高分辨率模式中的正确表示表明了水平分辨率在解决这些过程中的重要性。
The extra-tropical response to El Niño in a “low” horizontal resolution coupled climate model, typical of the Intergovernmental Panel on Climate Change fourth assessment report simulations, is shown to have serious systematic errors. A high resolution configuration of the same model has a much improved response that is similar to observations. The errors in the low resolution model are traced to an incorrect representation of the atmospheric teleconnection mechanism that controls the extra-tropical sea surface temperatures (SSTs) during El Niño. This is due to an unrealistic atmospheric mean state, which changes the propagation characteristics of Rossby waves. These erroneous upper tropospheric circulation anomalies then induce erroneous surface circulation features over the North Pacific. The associated surface wind speed and direction errors create erroneous surface flux and upwelling anomalies which finally lead to the incorrect extra-tropical SST response to El Niño in the low resolution model. This highlights the sensitivity of the climate response to a single link in a chain of complex climatic processes. The correct representation of these processes in the high resolution model indicates the importance of horizontal resolution in resolving such processes.