El Niño meets La Niña – anomalous rainfall patterns in the “traditional” El Niño region of southern Ecuador
El Niño meets La Niña – anomalous rainfall patterns in the “traditional” El Niño region of southern Ecuador
复制标题
厄尔尼诺现象与拉尼娜现象相遇——厄瓜多尔南部“传统”厄尔尼诺地区的异常降雨模式
DOI：
10.3112/erdkunde.2011.02.04
复制
发表时间：
2011
期刊：
影响因子：
1.4
通讯作者：
A. Bendix
中科院分区：
文献类型：
--
作者：
J. Bendix;Katja Trache;E. Palacios;R. Rollenbeck;Dietrich Goettlicher;T. Nauss;A. Bendix
利用厄瓜多尔南部气象站的降水资料、厄尔尼诺3区和1+2区的海表温度资料以及WRF模式的模拟结果，分析了2008年中太平洋冷事件及其在热带东太平洋的异常暖状况。可以看出，在中太平洋寒冷天气盛行的同时，厄瓜多尔南部沿海平原尤其会出现类似厄尔尼诺的降雨情况，造成严重的洪水泛滥。与以往情况相反，2008年拉尼娜事件期间，由于厄尔尼诺1 +2区域类似厄尔尼诺的情况，沿海平原和高地这两个区域首次出现正降雨量异常。对暴雨期间海洋-大气系统的详细分析揭示了典型的厄尔尼诺环流和降雨模式，沿海地区与以往厄尔尼诺事件期间观察到的情况相同，高地则类似于拉尼娜现象。太平洋不稳定在Niño 1 +2区域扩散到安第斯山脉东部悬崖可能是步行者环流暂时东移的结果。在中太平洋拉尼娜状态期间热带太平洋东部类似厄尔尼诺的情况不寻常地结合在一起，这是自上个世纪末以来厄瓜多尔南部传统厄尔尼诺地区厄尔尼诺/拉尼娜事件期间严重降雨异常影响模式转变的最新指标。自2000年以来，厄尔尼诺现象出乎意料地使降雨量低于平均水平，而中太平洋拉尼娜现象在通常较干燥的沿海平原造成异常严重的洪水。热带太平洋东部和中部/西部之间新的海表温度（SST）异常偶极结构以及2000年以来厄尔尼诺事件的减弱可能是由于厄尔尼诺背景态的自然年代际振荡--太平洋年代际振荡（PDO）。然而，所观察到的大气模式和最近增加的热带太平洋中部和东部之间的SST异常差异类似的结构，也导致气候变化模拟。
In this paper, the central Pacific cold event of 2008 and its exceptionally warm conditions in the eastern tropical Pacific are analyzed by using rainfall data of south Ecuadorian meteorological stations, sea surface temperatures in the El Niño3 and 1+2 regions, and simulations with the Weather Research and Forecasting (WRF) model. It can be shown that El Niño-like rainfall conditions with severe inundations occur particularly in the coastal plains of southern Ecuador while a central Pacific cold event prevails. In contrary to previous situations, positive rainfall anomalies as a result of El Niño-like conditions in the El Niño1+2 region during the 2008 La Niña event occurred in both regions, the coastal plains and the highlands, for the first time. A detailed analysis of the ocean-atmosphere system during episodes of heavy rainfall reveals typical El Niño circulation and rainfall patterns as observed during previous El Niño events for the coastal area and La Niña-like conditions for the highlands. The spreading of Pacific instability in the Niño1+2 region to the eastern escarpment of the Andes could be the result of a temporary eastward shift of the Walker circulation. The unusual combination of El Niño-like conditions in the eastern tropical Pacific during a La Niña state in the central Pacific is the newest indicator for an impact mode shift regarding severe rainfall anomalies during El Niño/La Niña events in the traditional El Niño area of southern Ecuador since the end of the last century. Since 2000, El Niño events unexpectedly provide below average rainfall while central Pacific La Niña conditions generate exceptional severe flooding in the normally drier coastal plains. The novel sea surface temperature (SST) anomaly dipole structure between the eastern and central/western tropical Pacific and the weakening of El Niño events since 2000 could be due to natural decadal oscillations in the El Niño background state, the Pacific Decadal Oscillation (PDO). However, the observed atmospheric patterns and the recent increase of the SST anomaly difference between the central and the eastern tropical Pacific resemble structures that also result from climate change simulations.