Impact of global warming on western North Pacific circulation anomaly during developing El Nino
Impact of global warming on western North Pacific circulation anomaly during developing El Nino
复制标题
厄尔尼诺发展过程中全球变暖对北太平洋西部环流异常的影响
DOI：
10.1175/jcli-d-19-0588.1
复制
发表时间：
2020
影响因子：
4.9
通讯作者：
Tim Li
中科院分区：
文献类型：
--
作者：
Yuhao Wang;Chao He;Tim Li
厄尔尼诺现象在其发展阶段刺激北太平洋上空的异常气旋。利用来自CMIP5的30个CGCM和11个AGCM，我们发现了一个弱加强的异常北太平洋气旋（NPC）在一个温暖的气候中的CGCM，模式间的不确定性存在。在平均状态SST增加的AGCM中，也发现了类似的异常NPC变化，但增强幅度更大。基于一个简单的Gill模式，非绝热加热异常，平均状态静力稳定度，相对涡度的纬向梯度的异常NPC的变化负责。对CMIP5模式的分析表明，非绝热加热异常的增强与平均状态静稳定度的增强之间的竞争在很大程度上决定了NPC异常的变化。赤道中东太平洋降水异常的变化强烈地调制着NPC异常增强的幅度，而赤道中东太平洋降水异常的变化又依赖于平均状态SST的变化和与厄尔尼诺相关的SST异常。与均匀增暖相比，类厄尔尼诺平均状态海温增暖通过增强赤道太平洋平均状态降水和与降水异常相关的潜热异常，更有利于NPC异常的增强。然而，海气耦合作用减弱了与厄尔尼诺相关的海表温度异常，从而进一步减弱了NPC异常的增强。
El Niño stimulates an anomalous cyclone over the North Pacific during its developing phase. Using 30 CGCMs and 11 AGCMs from CMIP5, we find a weakly strengthened anomalous North Pacific cyclone (NPC) in a warmer climate in CGCMs, and intermodel uncertainty exists. A similar change of the anomalous NPC is found in AGCMs with increased mean state SST but with a stronger amplitude of enhancement. Based on a simple Gill model, the diabatic heating anomaly, mean state static stability, and meridional gradient of relative vorticity are identified to be responsible for the change of the anomalous NPC. Analyses of the CMIP5 models suggest that the change of the anomalous NPC is largely determined by the competition between the enhanced diabatic heating anomaly and the enhanced mean state static stability. The amplitude of enhancement of the anomalous NPC is strongly modulated by the change of precipitation anomaly over the equatorial central-eastern Pacific, which depends on the changes of mean state SST and the El Niño–related SST anomaly. Compared with a uniform warming, an El Niño–like mean state SST warming favors a much stronger enhancement of the anomalous NPC, by enhancing the mean state precipitation and latent heating anomaly associated with the precipitation anomaly over the equatorial Pacific. However, the air–sea coupling acts to weaken the SST anomaly associated with El Niño in the CGCMs, which further reduces the enhancement of the anomalous NPC.