两类厄尔尼诺背景下MJO对太平洋阻塞频率的调节作用  

Impact of Madden–Julian Oscillation on Pacific Blocking Frequency during Two Types of El Niño

作　　者：高铭祥 杨双艳[1,3] 王强 李天明[1,4] GAO Mingxiang;YANG Shuangyan;WANG Qiang;LI Tianming(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC–FEMD)/Joint International Research Laboratory of Climate and Environmental Change(ILCEC),Nanjing University of Information Science and Technology,Nanjing 210044;Guangzhou Meteorological Observatory,Guangzhou 511430;State Key Laboratory of Tropical Oceanography(South China Sea Institute of Oceanology,Chinese Academy of Sciences),Guangzhou 510301;Department of Atmospheric Sciences,International Pacific Research Center,University of Hawaii at Manoa,Honolulu,Hawaii,USA 96822)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心/气候与环境变化国际合作联合实验室,南京210044 [2]广州市气象台,广州511430 [3]热带海洋环境国家重点实验室(中国科学院南海海洋研究所),广州510301 [4]夏威夷大学马诺阿分校大气科学学院国际太平洋研究中心,美国夏威夷96822

出　　处：《大气科学》2023年第2期487-501,共15页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金项目42088101;江苏省自然科学基金项目BK20210660;热带海洋环境国家重点实验室(中国科学院南海海洋研究所)开放课题LTO2116。

摘　　要：本文基于1979~2019年ERA-interim逐日再分析数据和二维阻塞指数,探究了冬季两类(中部型和东部型)厄尔尼诺背景下热带季节内振荡(MJO)对太平洋地区阻塞频率的调节作用。本研究选取出现频次较高且平均振幅较强的位相3和7进行研究。结果表明,在两类厄尔尼诺背景下MJO第3位相期间,MJO激发的遥相关位置相似,均对应极地地区(白令海地区)正(负)的位势高度异常,从而使高纬度太平洋地区均出现正的阻塞频率异常。在东部型厄尔尼诺背景下MJO第7位相(EP7)期间中高纬太平洋地区存在正的阻塞频率异常。但是在中部型厄尔尼诺背景下MJO第7位相(CP7)期间没有大范围显著的异常阻塞频率。这是因为EP7期间MJO激发的异常Rossby波源位于急流核区的西北部,使得MJO的遥相关可以传至50°N以北,引起中高纬度地区有利于阻塞频率增加的位势高度异常。然而CP7期间MJO激发的异常Rossby波源位于急流核区内部,使得对应的遥相关仅在副热带急流中传播,对高纬度地区的位势高度影响较小,导致该时期内没有大范围显著的阻塞频率异常。最后本文使用ECHAM4.6气候模式验证了上述结论。The influence of the Madden–Julian Oscillation(MJO)on Pacific blocking frequency during two kinds of El Niño(Eastern Pacific and Central Pacific El Niño)is investigated using a two-dimensional blocking index in winter,based on ERA-interim reanalysis of daily data from 1979 to 2019.In this research,phases 3 and 7 were chosen because they had a greater frequency.In MJO phase 3,during the Eastern Pacific and Central Pacific El Niño years(EP3 and CP3),the sites of MJO teleconnections are found to be comparable,correlating to a positive(negative)geopotential height anomaly in the polar area(the Bering Sea).Thus,during EP3 and CP3,there are positive blocking frequency anomalies in the high-latitude Pacific sector.Blocking frequency anomalies across the mid-high-latitudinal Pacific are notably positive in MJO phase 7 during the Eastern Pacific El Niño years(EP7)but not so much in MJO phase 7 during the Central Pacific El Niño years(CP7).Because the MJO-related anomalous Ross wave source is located northwest of the EP7 subtropical jet core region,the MJO teleconnection is located north of 50°N.This teleconnection relates to geopotential height abnormalities in the Pacific sector,which enhance the frequency of Pacific blocking.However,during the CP7,the MJO-related anomalous Rossby wave source was located in the subtropical jet core region.The associated teleconnection propagates across the subtropical jet stream,exerting a negligible impact on the geopotential height in the Pacific area.Thus,there are no statistically significant blocking frequency anomalies in the CP7 across the Pacific area.Finally,the ECHAM4.6 model is used to validate the results.

关 键 词：太平洋阻塞频率 热带季节内振荡(MJO) 东部型厄尔尼诺 中部型厄尔尼诺 

分 类 号：P461[天文地球—大气科学及气象学]