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Wang Zhongpeng,Zhang Zhaoru,Zhou Meng,Liu Hailong,Zhong Yisen,Wang Xiaoqiao. 2020. Seasonal linkage of the Southern Hemisphere extratropical climate variability to two types of ENSO. Acta Oceanologica Sinica, 39(1):63－73

Seasonal linkage of the Southern Hemisphere extratropical climate variability to two types of ENSO

南半球热带外气候变量与两种ENSO的联系

Received:October 28, 2018

DOI：10.1007/s13131-019-1528-x

Key words:Southern Hemisphere extratropical climate El Niño-Southern Oscillation eastern Pacific type central Pacific type

中文关键词: 南半球热带外气候厄尔尼诺-南方涛动东太平洋型中太平洋型

基金项目:The General Program of the National Natural Science Foundation of China under contract Nos 41876221 and 41861134040.

Author Name	Affiliation	E-mail
Wang Zhongpeng	Institute of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China
Zhang Zhaoru	Institute of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China	zrzhang@sjtu.edu.cn
Zhou Meng	Institute of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China
Liu Hailong	Institute of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China
Zhong Yisen	Institute of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China
Wang Xiaoqiao	Institute of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China

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Abstract:

This study uses the Climate Forecast System Reanalysis (CFSR) to investigate the responses of the Southern Hemisphere (SH) extratropical climate to two types of El Niño-Southern Oscillation (ENSO)-the eastern Pacific (EP) type and the central Pacific (CP) type in different seasons. The responses are denoted by the anomalies of climate variables associated with one-standard-deviation increase in the Niño3 or Niño4 index. The results show that in austral spring the differences in the ENSO-related anomaly (ERA) patterns of atmospheric circulation between the EP ENSO period (1979–1998) and CP ENSO period (1999–2010) are mainly associated with the change in the ENSO-PSA2 relationship. Such differences affect the ERA fields of surface air temperature and mixed layer temperature, and finally result in significant differences in sea-ice concentration anomalies in the Atlantic sector. In austral summer, significant correlation exists between the variations of SAM and both of the variations of Niño3 and Niño4 in 1979–1998, while the correlation between SAM and Niño4 disappears in 1999–2010. For all seasons, the strength of the climate ERAs depend on if there are close relationship between ENSO and the major climate variation modes of the SH extratropics. For the climate variables, the ERA patterns of surface air temperature are generally controlled by surface wind anomalies and mirrored by the mixed layer temperature anomalies. The mixed layer depth anomalies are primarily modulated by surface heat flux anomalies and occasionally by anomalous wind. There are strikingly strong anomalies of surface heat flux in the autumn of 1979–1998 related to the Niño3 variation, the period when there is only significant correlation between ENSO and PSA2. There are no evidence that the SH extratropical climate variability induced by Niño3 variations are stronger in the EP-ENSO period, and that variability induced by Niño4 variations are stronger in the CP-ENSO period.

中文摘要:

本研究利用气候预测系统再分析资料（CFSR）研究南半球热带外气候变量在不同季节对两种厄尔尼诺-南方涛动（ENSO）-东太平洋型（EP）和中太平洋型（CP）的响应。响应由Niño3或Niño4指数增加一个标准差导致的气候变量异常表示。结果表明，在南半球春季，东部型ENSO占主导期间（1979-1998）和中部型ENSO占主导期间（1999-2010），ENSO相关的大气环流异常差异主要与ENSO-PSA2关系的变化有关。这些差异影响了海表气温和海洋混合层温度对ENSO变化的异常场，最终导致大西洋地区海冰浓度异常的显著差异。在南半球夏季，1979-1998年SAM与Niño3和Niño4存在显著的相关，而1999-2010年SAM与Niño4的相关性消失。在所有季节中，ENSO变化引起的各气候变量异常的强弱取决于ENSO与南半球热带外主要气候模态之间是否存在密切关系。对于气候变量而言，ENSO变化引起的海表面气温异常一般受海表面风异常影响，并通过混合层温度异常反映出来；混合层深度异常主要受海表热通量异常影响，偶尔受异常风影响。1979-1998年秋季海表热通量对Niño3变化存在显著的强异常，这一时期ENSO与PSA2之间只有显著的相关性。没有证据表明，在东部型ENSO占主导地位期间，由Niño3变化引起的南半球热带外气候异常更强，在中部型ENSO占主导地位期间，由Niño4变化引起的南半球热带外气候异常更强。

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