Contrasting Impacts of Two Types of ENSO on the Boreal Spring Hadley Circulation
Contrasting Impacts of Two Types of ENSO on the Boreal Spring Hadley Circulation
复制标题
两种ENSO对北春季哈德利环流的影响对比
DOI：
10.1175/jcli-d-12-00298.1
复制
发表时间：
2013-07-01
影响因子：
4.9
通讯作者：
Li, Jianping
中科院分区：
文献类型：
--
作者：
Feng, Juan;Li, Jianping
两种类型的ENSO的可能影响[即，研究了1979 - 2010年春季典型ENSO和ENSO Modoki（EM）]对Hadley环流的影响。厄尔尼诺事件的特征是赤道纬向平均海表温度距平（SSTA）的对称型，最大值出现在赤道附近。与此相反，与ElNino Modoki事件相关的纬向平均SSTA显示出不对称结构，最大值在10 ° N附近。ENSO和EM对应的下垫面热力结构对同时发生的HC有相反的影响。在厄尔尼诺年，赤道附近的赤道环流出现对称的异常纬向环流，在北纬15度和南纬20度附近，赤道附近的上升和异常下降增强。与此相反，在厄尔尼诺-莫多基年，观测到一个不对称的赤道纬向环流，在北纬10度附近异常上升，在南纬10度和北纬20度附近异常下降。ENSO和EM中纬向环流异常的对比是由它们不同的纬向SSTA结构造成的。对这一结果进行了理论解释，指出纬向环流异常受纬向海温梯度的影响。此外，观测结果在东太平洋和中太平洋异常变暖驱动的数值试验中重现。因此，作者认为与ENSO和EM有关的异常HC是由纬向平均SSTA中伴随的纬向梯度引起的。
The possible influences of two types of ENSO [i.e., the canonical ENSO and ENSO Modoki (EM)] on Hadley circulation (HC) during the boreal spring are investigated during 1979-2010. El Nino events are featured with a symmetric pattern in equatorial zonal-mean sea surface temperature anomalies (SSTA), with a maximum around the equator. In contrast, the zonal-mean SSTA associated with El Nino Modoki events shows an asymmetric structure with a maximum around 10 degrees N. The contrasting underlying thermal structures corresponding with ENSO and EM have opposite impacts on the simultaneous HC. In El Nino years, a symmetric anomalous meridional circulation is seen, with enhanced rising around the equator and anomalous descent at about 15 degrees N and 20 degrees S. In contrast, an asymmetric equatorial meridional circulation is observed for El Nino Modoki years, with anomalous ascent around 10 degrees N and descent at about 10 degrees S and 20 degrees N. The contrasting meridional circulation anomalies within ENSO and EM are caused by their different meridional SSTA structure. This result is theoretically explained, indicating that anomalous meridional circulation is subject to the meridional SSTA gradient. Moreover, the observed results are reproduced in numerical experiments driven by anomalous warming in the eastern and central Pacific Ocean. Thus, the authors conclude that the anomalous HC linked to ENSO and EM is induced by the accompanying meridional gradient in zonal-mean SSTA.