Comparison of the seasonal evolution of the South Asian high associated with two types of El Niño event

Zhen-Kun Li,Yu-Cheng Su,Dong Guo,Jia-Xi Cai,Lin-Wei Wang,Li-Long Zhao,Chun-Hua Shi

doi:10.1080/16742834.2017.1270161

Abstract

AbstractEl Nino (EN) episodes can be classified based on their time of onset as spring onset EN (SPEN) events and summer onset EN (SUEN) events. To evaluate the different influences of SPEN and SUEN events on the South Asian high (SAH), this study compared the seasonal evolution of the SAH (SESAH) associated with SPEN and SUEN events through analysis of geopotential height and zonal wind data derived from NCEP–NCAR Reanalysis-1 and sea surface temperature data obtained from the Hadley Center. The main features of the SESAH during an EN event are similar to its climatological characteristics. Climatologically, the SAH forms in May, strengthens, and moves northwestward in June and July. It does not change much in August, but then it returns south and weakens during September and October. However, its lifespan is shorter and its intensity weaker during EN periods. Furthermore, there are significant differences between the SESAH during SPEN and SUEN events. During a SPEN episode, the movement of the SAH to th...

Highlights

The South Asian high (SAH) is one of the most important atmospheric systems of the summer Asian monsoon (e.g. Tao and Chen 1957; Zhu et al 1980; Zhang et al 1988)
Qian, and Zhang (2000) indicated that the intensity of the SAH has a significant relationship with sea surface temperature (SST) anomalies (SSTAs), i.e. the El Niño (EN)/La Niña (LN) associated with the Tibetan/Iranian high mode of the SAH
In May, the SAH is located over Southeast Asia and the Bay of Bengal

Summary

Introduction

The South Asian high (SAH) is one of the most important atmospheric systems of the summer Asian monsoon (e.g. Tao and Chen 1957; Zhu et al 1980; Zhang et al 1988). The seasonal evolution and variability of the SAH has considerable impact on the atmospheric circulation of the Northern Hemisphere in general, and on the climate and summertime weather in Asia (e.g. Tao and Zhu 1964; Zhu et al 1980; Luo, Qian, and Wang 1982; Sun and Song 1987; Zhang, Wu, and Qian 2002). Given the importance of the SAH to the atmospheric circulation of the Northern Hemisphere, it is reasonable to investigate the different influences of SPEN and SUEN events on the development and lifespan of the SAH.

Data and method

Seasonal evolution of the SAH

Comparison of the SESAH associated with the SPEN and SUEN