夏季印度洋MJO活跃时间对中国长江流域降水日数的影响  

Influence of MJO active days over the Indian Ocean on precipitation days in the reaches of the Yangtze River

作　　者：雷徐奔[1] 张文君[1] 刘超[1] LEI Xuben;ZHANG Wenjun;LIU Chao(Key Laboratory of Meteorological Disaster,Ministry of Education/International Joint Laboratory on Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing 210044,China)

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/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心,南京210044

出　　处：《气象学报》2022年第4期503-514,共12页Acta Meteorologica Sinica

基　　金：国家自然科学基金项目(42125501、42088101)。

摘　　要：利用1980—2020年中国753站逐日降水资料、NCEP/NCAR大气再分析资料以及哈得来中心的海表温度资料和实时多变量Madden-Julian振荡(MJO)指数,研究了MJO在印度洋地区(1—3位相)活跃日数对长江流域夏季降水日数的影响。结果表明两者存在显著的统计联系,在MJO活跃日数偏多的年份,MJO相关的西北太平洋反气旋环流异常有利于向长江中下游地区输送水汽,进而导致长江流域中下游范围内降水日数的增加,且这种影响主要体现在降水等级为大雨(25 mm/d)及以上强度的日数上。进一步研究发现,MJO在印度洋活跃日数与长江中下游夏季降水日数的关系存在年代际变化,两者显著的联系仅出现在2000年之后,之前的时段两者联系则较弱。这种关系的转变可能与印度洋海表温度变率减弱的背景有关,印度洋海洋年际变率变弱导致其对于长江中下游地区的影响减弱,进而使得MJO的调控作用凸显出来。夏季季节平均的印度洋MJO活跃日数可以对长江中下游的大雨以上的降水日数产生影响,且两者的关系在大约2000年之后变得尤为显著。The influences of active days of the Madden-Julian oscillation(MJO)over the Indian Ocean on summer precipitation days over the middle and lower reaches of the Yangtze River were investigated.Daily precipitation data collected at 753 stations,monthly sea surface temperature(SST)data from the Hadley Centre,daily mean reanalysis data from the National Centers for the Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR),and all-season real-time multivariate Madden-Julian Oscillation(RMM)index during 1980—2020 were used.The results show that the active days of MJO over the Indian Ocean have a statistically significant relationship with precipitation days over the middle and lower reaches of the Yangtze River,especially with the heavy precipitation days,since the MJO related circulation anomalies can continuously transport water vapor to eastern China.Further research indicates that the relationship between active days of MJO over the Indian Ocean and the precipitation days over the middle and lower reaches of the Yangtze River has experienced a decadal change with their relationship being significant since the 2000s.The decadal change of this relationship might be attributed to decreased variability in SST in the Indian Ocean.This decreased interannual variability of SST suggests weakened modulation effects on precipitation over the middle and lower reaches of the Yangtze River by the tropical Indian Ocean.In contrast,the MJO effects on the precipitation days over the middle and lower reaches of the Yangtze River turn to be significant after the 2000s due to less disturbances from the Indian Ocean SST.

关 键 词：Madden-Julian振荡(MJO) 降水日数 年际变率 长江中下游地区 

分 类 号：P46[天文地球—大气科学及气象学]