摘要
利用1979—2012年NCEP/NCAR逐日再分析资料、澳大利亚气象局MJO指数数据、中国台站逐日降水观测资料、NOAA逐月海表温度资料,分析了印太海盆增暖对冬季MJO的影响及其与中国冬季降水变化的关系。结果表明:在印太海盆增暖背景下,热量和水汽输送的增强导致MJO各位相强度均有增强,其中第6位相强度增强最明显。水汽垂直分布结构的改变不仅有利于MJO第4位相继续东传,而且有利于MJO在第5位相滞留,引起MJO第5位相频数异常增多。上述MJO的变化引起的局地Hadley环流下沉支位于华南地区,导致了2001—2010年与MJO第5—6位相相关的华南地区次季节性降水异常减少。
The Madden-Julian Oscillation(MJO)is the dominant mode of intraseasonal variability in the tropics and has been widely studied since its discovery by Madden and Julian in 1971.The tropical oceans are a critical source of moisture,and positive sea surface temperature(SST)anomalies enhance heating and moisture fluxes,which facilitate the initialization and propagation of the MJO.Observations reveal a significant warming trend in the tropical Indian Ocean and western Pacific(TWIP)since 1979,associated with anthropogenic greenhouse gas forcing.However,previous studies indicate that current climate models struggle to simulate MJO variability accurately,underscoring the challenges in understanding its role in weather and the climate systems.This study examines the observed impacts of SST warming in the TWIP on the MJO,focusing on changes in its characteristics and their influence on winter precipitation in China from 1979 to 2012.South China,where precipitation is heaviest,has experienced a significant increase in rainfall since 1979,making it vital to investigate the contribution of MJO changes to this trend.The analysis reveals that SST warming in the TIWP intensifies heating and moisture fluxes,leading to an increase in MJO amplitude across all phases,with a statistical significant rise in phase 6.Vertical water vapor distribution changes result in an increased frequency of MJO phases,particularly phase 5,facilitating eastward propagation from phase 4 to phase 5 and prolonging phase 5 activity.These MJO changes are linked to enhanced subsidence in South China,associated with local Hadley cell dynamics,resulting in more negative sub seasonal precipitation anomalies during MJO phases 5 and 6 in recent decades.The findings provide observational evidence of the significant influence of SST warming on MJO activity and its subsequent impacts on regional precipitation patterns.The results highlight that MJO phase frequency changes reflect shifts in preferred regions of activity and structural adjustments.Future research sh
作者
王礼松
杨栎楠
姚永红
吴其冈
WANG Lisong;YANG Linan;YAO Yonghong;WU Qigang(School of Atmospheric Sciences,Nanjing University,Nanjing 210023,China;Meteorological Center,Southwest Regional Air Traffic Management Bureau,CAAC,Chengdu 610000,China;Fujian Key Laboratory of Severe Weather,Fuzhou 350008,China;Department of Atmospheric and Oceanic Sciences/Institute of Atmospheric Sciences,Fudan University,Shanghai 200000,China)
出处
《大气科学学报》
CSCD
北大核心
2024年第6期856-866,共11页
Transactions of Atmospheric Sciences
基金
福建省灾害天气重点实验室开放课题(2022KFKT01)
国家自然科学基金重大研究计划重点项目(91837206)。
