Amplifying effect of ENSO on heat waves in China
Amplifying effect of ENSO on heat waves in China
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DOI：
10.1007/s00382-018-4322-0
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发表时间：
2019-03-01
期刊：
影响因子：
4.6
通讯作者：
Lau, Ngar-Cheung
中科院分区：
文献类型：
--
作者：
Luo, Ming;Lau, Ngar-Cheung
本文研究了1961-2014年厄尔尼诺南方涛动（ENSO）对中国热浪（HWs）频率、持续时间和强度等各个方面的影响。结果表明，厄尔尼诺（拉尼娜）对我国大部分地区的水汽活动有明显的放大（减弱）作用。这种影响在中国南方尤其强烈。HW活动增强（减弱）在夏季成熟的厄尔尼诺（拉尼娜）事件，增加（减少）HW事件的发生和HW天数，以及延长（缩短）的持续时间和升高（降低）的幅度等事件。这些放大效应对于严重的HW（即，最热和最长的事件）比那些平均持续时间和强度的事件。对ENSO事件再分析资料的综合诊断表明，El Nino后夏季大气环流的特征是热带中太平洋和印度洋的异常上升运动和西北太平洋（WNP）的异常下沉运动。西北太平洋的异常沉降伴随着降水和凝结加热的减少，以及对流层低层的异常反气旋流。厄尔尼诺还导致南亚高压增强，使西北太平洋高压和副热带高压加强。这些变化为HWs在中国的发生和维持提供了有利的环境。类似的论点适用于与拉尼娜事件相关的相反极性的变化。
This paper investigates the impacts of the El Nino Southern Oscillation (ENSO) on various aspects of heat waves (HWs), including frequency, duration, and magnitude, over China during 1961-2014. Results show that El Nino (La Nina) significantly amplifies (weakens) the HW activities in most areasof China. Such influences are particularly strong in southern China. HW activities are enhanced (weakened) during the summers following mature El Nino (La Nina) episodes, with increased (reduced) occurrence of HW events and number of HW days, as well as prolonged (shortened) duration and elevated (decreased) amplitude of such events. These amplifying effects are substantially stronger for severe HWs (i.e., hottest and longest episodes) than for those events of average duration and intensity. Diagnosis by compositing reanalysis data over ENSO events indicates that the atmospheric circulation during the summers following El Nino is characterized by anomalous rising motion over the tropical central Pacific and Indian Oceans, and sinking motion over the western North Pacific (WNP). The anomalous subsidence over theWNP is accompanied by reduced precipitation and condensational heating, as well as anomalous anticyclonic flows in the lower troposphere. El Nino also induces a stronger South Asian high, which can strengthen the WNP anticyclone and subtropical high. These changes provide a favorable environment for the occurrence and sustenance of HWs in China. Analogous arguments apply to changes with the opposite polarity in association with La Nina events.