Impacts of two types of La Niña on the NAO during boreal winter
Impacts of two types of La Niña on the NAO during boreal winter
复制标题
DOI：
10.1007/s00382-014-2155-z
复制
发表时间：
2015-03
期刊：
影响因子：
4.6
通讯作者：
Wenjun Zhang;Lei Wang;B. Xiang;L. Qi;Jinhai He
中科院分区：
文献类型：
--
作者：
Wenjun Zhang;Lei Wang;B. Xiang;L. Qi;Jinhai He
本文根据海温距平的空间分布，确定了两种La Niña类型。与东太平洋(EP)拉尼娜事件,一种新型的拉尼娜现象(太平洋中部、CP拉尼娜现象),对海温在CP冷却中心。这两种拉尼娜展览海温异常演化的根本区别:EP拉尼娜现象显示了向西传播特性而CP拉尼娜展品在CP站功能。这两种类型的拉尼娜现象会产生一个明显不同的全球远程并置对比。作为对EP La Niña的响应，北大西洋(NA) -西欧（WE）地区经历了类似于负北大西洋涛动（NAO）模式的大气异常，同时伴随着大西洋急流的减弱。它导致西欧的冬天比正常的冬天更凉爽、更干燥。然而，CP La Niña对NA-WE气候的影响大致相反。在大西洋急流增强的情况下，观测到一个正的类似nao的气候异常，西欧上空出现了一个比正常冬季更温暖、更潮湿的冬季。模拟实验表明，上述对比的大气异常主要归因于两类La Niña不同的海温冷却模式。它们的信号混淆会导致对区域气候的季节性预测出现困难。由于La Niña-related海温异常是在发展中的秋季明显观测到的，因此可以提前一个季节预测西欧冬季气候异常。
The present work identifies two types of La Niña based on the spatial distribution of sea surface temperature (SST) anomaly. In contrast to the eastern Pacific (EP) La Niña event, a new type of La Niña (central Pacific, or CP La Niña) is featured by the SST cooling center over the CP. These two types of La Niña exhibit a fundamental difference in SST anomaly evolution: the EP La Niña shows a westward propagation feature while the CP La Niña exhibits a standing feature over the CP. The two types of La Niña can give rise to a significantly different teleconnection around the globe. As a response to the EP La Niña, the North Atlantic (NA)–Western European (WE) region experiences the atmospheric anomaly resembling a negative North Atlantic Oscillation (NAO) pattern accompanied by a weakening Atlantic jet. It leads to a cooler and drier than normal winter over Western Europe. However, the CP La Niña has a roughly opposing impact on the NA–WE climate. A positive NAO-like climate anomaly is observed with a strengthening Atlantic jet, and there appears a warmer and wetter than normal winter over Western Europe. Modeling experiments indicate that the above contrasting atmospheric anomalies are mainly attributed to the different SST cooling patterns for the two types of La Niña. Mixing up their signals would lead to difficulty in seasonal prediction of regional climate. Since the La Niña-related SST anomaly is clearly observed during the developing autumn, the associated winter climate anomalies over Western Europe could be predicted a season in advance.