SAM和ENSO对罗斯海和阿蒙森海区域冬季气候的影响  

Effects of SAM and ENSO on winter climate over the Ross Sea and the Amundsen Sea

作　　者：谢川 张召儒 周朦[1] Xie Chuan;Zhang Zhaoru;Zhou Meng(School of Oceanography,Shanghai Jiao Tong University,Shanghai 200030,China)

机构地区：[1]上海交通大学海洋学院,上海200030

出　　处：《极地研究》2023年第2期167-182,共16页Chinese Journal of Polar Research

基　　金：国家自然科学基金(41876221,41941008);国家重点研发计划(2019YFC1509102);上海市科委科技基金(20230711100,21QA1404300);南极重点海域对气候变化的响应和影响专项(IRASCC2020-2022-No.1-02-01B)资助。

摘　　要：本研究利用ERA5数据对南半球环状模(SouthernAnnularMode,SAM)正、负位相和ENSO(El Ni?o-SouthernOscillation)事件发生时罗斯海和阿蒙森海冬季风场、气温和海平面气压进行合成分析,并深入分析了SAM和ENSO对冬季阿蒙森低压(Amundsen Sea Low,ASL)的影响,通过对典型区域进行经验正交分解(Empirical Orthogonal Function,EOF),结合ASL中心的位置变化,解释了SAM和ENSO事件同时发生时该区域风场的变化特征。结果表明,在罗斯海和西阿蒙森海,主要由SAM和ENSO通过影响ASL的纬向位置来影响该区域的风场,当SAM正位相和拉尼娜事件同时发生时,ASL的位置显著靠东,造成了西罗斯海南风减弱,东罗斯海南风加强,西阿蒙森海沿岸东风减弱。而在东阿蒙森海,主要由SAM通过影响ASL的经向位置来影响该区域的风场,SAM负位相时,ASL中心位置靠北会造成东阿蒙森海东风增强。此外,ASL位置的偏移也会造成该区域大气环流的改变,当SAM正位相和拉尼娜事件同时发生时,ASL偏移至西阿蒙森海沿岸,而从南极大陆来的寒冷气流主导了该区域,造成气温异常降低,降幅最大超过3℃。This study used ERA5 data to conduct composite analysis of wind,air temperature,and sea level pressure in winter over the Ross and Amundsen seas when Southern Annular Mode(SAM)and E1 Niño-Southern Oscillation(ENSO)events occurred simultaneously,and further analyzed the effects of SAM and ENSO on the Amundsen Sea Low(ASL)in winter.Variational characteristics of regional wind during different periods were explained by Empirical Orthogonal Function(EOF)decomposition of typical regions with consideration of changes in the central position of the ASL.Results showed that SAM and ENSO mainly affect the wind by altering the zonal position of the ASL in the Ross Sea and the western Amundsen Sea.When the positive phase of SAM coincides with a La Niña event,the ASL is displaced eastward,resulting in weakening(strengthening)of southerly winds in the western(eastern)Ross Sea and weakening of easterly winds along the coast of the western Amundsen Sea.In the eastern Amundsen Sea,SAM mainly affects the regional wind by changing the meridional position of the ASL.When SAM is in negative phase,the more northerly position of the ASL leads to stronger easterly winds in the eastern Amundsen Sea.Additionally,positional offset of the ASL changes the regional atmospheric circulation.When the positive phase of SAM coincides with a La Niña event,the ASL is centered close to the western coast of the Amundsen Sea,and cold air flowing from the Antarctic continent dominates the region,resulting in abnormally low air temperatures with maximum reduction of>3℃.

关 键 词：SAM ENSO ASL 罗斯海 阿蒙森海 冬季气候 

分 类 号：P461[天文地球—大气科学及气象学]