Physical Oceanography Laboratory/CIMST, Ocean University of China and Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266100, China.
Department of Oceanography, Texas A&M University, College Station, Texas, 77843, USA.
Sci Rep. 2017 May 10;7(1):1658. doi: 10.1038/s41598-017-01962-3.
Hurricane Patricia in 2015 was the strongest Pacific hurricane to make landfall in Mexico. Although Patricia fortuitously spared major cities, it reminded us of the threat tropical cyclones (TCs) pose in the eastern North Pacific (ENP) and the importance of improving our understanding and prediction of ENP TCs. Patricia's intensity and the active 2015 ENP hurricane season have been partially attributed to the strong El Niño in 2015, however there is still a lack of fundamental understanding of the relationship between El Niño-Southern Oscillation (ENSO) and ENP TCs. Here, we demonstrate that ENSO drives intrabasin variability of ENP TCs, with enhanced (reduced) TC frequency in the western portion of the ENP during El Niño (La Niña), but reduced (enhanced) TC frequency in the eastern nearshore area, where landfalling TCs preferentially form. This intrabasin difference is primarily driven by the Central American Gap Winds (CAGW), which intensify (weaken) during El Niño (La Niña), producing low-level anticyclonic (cyclonic) relative vorticity anomalies and thus an unfavorable (favorable) environment for TC genesis. These findings shed new light on the dynamics linking ENP TC activity to ENSO, and highlight the importance of improving CAGW representation in models to make skillful seasonal forecasts of ENP TCs.
2015 年的飓风“帕特里夏”是登陆墨西哥的最强太平洋飓风。虽然“帕特里夏”幸运地避开了主要城市，但它提醒我们热带气旋（TC）在东北太平洋（ENP）构成的威胁，以及提高我们对 ENP TC 的理解和预测的重要性。“帕特里夏”的强度和 2015 年活跃的东北太平洋飓风季节部分归因于 2015 年强烈的厄尔尼诺现象，但人们对厄尔尼诺-南方涛动（ENSO）与东北太平洋 TC 之间的关系仍缺乏基本了解。在这里，我们表明，ENSO 驱动东北太平洋 TC 的流域内变异性，在厄尔尼诺期间，东北太平洋西部的 TC 频率增加（减少），而在近海东部地区的 TC 频率减少（增加），这里是登陆 TC 优先形成的地区。这种流域内的差异主要是由中美洲海峡风（CAGW）驱动的，CAGW 在厄尔尼诺（拉尼娜）期间增强（减弱），产生低层反气旋（气旋）相对涡度异常，从而为 TC 生成提供不利（有利）环境。这些发现为将东北太平洋 TC 活动与 ENSO 联系起来的动力学提供了新的认识，并强调了改进 CAGW 在模型中的表现以对东北太平洋 TC 进行熟练的季节性预测的重要性。
