东亚夏季风对山西省夏季降水的影响  

Effect of East Asian Summer Monsoon on Summer Precipitation in Shanxi Province

作　　者：李智才[1,2] 宋燕[2] 武永利[1] 王沛涛[3] 

机构地区：[1]山西省气候中心,太原030006 [2]中国气象局培训中心,北京100081 [3]河北省邯郸市气象局,邯郸056001

出　　处：《气候与环境研究》2010年第6期797-807,共11页Climatic and Environmental Research

基　　金：山西省气象局开放式研究基金SX042002;国家科技支撑计划课题"气候变化的检测和预估技术研究"(2007BAC03A01);"持续性异常气象事件预测业务技术研究"(2009BAC51B00);中国气象局气候研究开放实验室2006年度开放课题LCS-2006-01

摘　　要：利用NCEP1948～2007年逐日再分析资料、中国600站1960～2007年逐月降水资料和山西省1960～2007年65个测站的逐月、逐日降水资料,确立了850hPa112.5°E上候平均的假相当位温(θse)为340K和候平均的经向风为南风且南风风速≥2.5m·s-1等值线同时通过35°N的日期,将其作为山西省夏季风建立的时间,以θse≥340K的持续候数与平均持续候数相比的标准化值构造为东亚夏季风对山西省影响的强度指数I,可以较好地表征东亚季风区夏季风的强度和降水的空间分布,也可以较好地反映山西省夏季降水的强度和空间分布。该季风指数的年代际变化特征和线性趋势表明,自20世纪70年代以来东亚夏季风对山西省的影响有明显减弱的趋势,并且在1967年季风指数突变性地由强变弱。对山西省夏季风的建立和撤退时间的分析表明,近60年来东亚夏季风对山西省的影响时间越来越短。最后,分析了强弱夏季风指数年大气环流场的异常特征。By using NCEP daily reanalysis data for 1948-2007,monthly precipitation data at 600 observation stations in China for 1960-2007,and monthly and daily precipitation data at 65 observation stations in Shanxi Province for 1960-2007,the date for summer monsoon onset in Shanxi Province was confirmed by verifying the date on which both isolines of pentadly mean potential pseudo-equivalent temperature θse=340 K and pentadly mean meridional south wind speed ≥2.5 m·s-1 overpass 35°N synchronously along 112.5°E on 850 hPa. The summer monsoon index I was constructed by standardizing the ratio of persisting pentads of θse≥340 K to its normal mean pentads. It was verified that I can represent not only the intensity and spatial pattern of East Asian summer monsoon quite well,but also those of summer precipitation in Shanxi Province. The interdecadal variability and linear trend of I showed that the influence of East Asian summer monsoon on precipitation in Shanxi Province has weakened obviously since the 1970s,and the abrupt change was around 1967. Analysis on the dates of summer monsoon onset and retreat in Shanxi Province indicated that the persisting time of the summer monsoon is shorter in recent 48 years. Finally,the characteristics of the general circulations for strong and weak summer monsoon indcies were analyzed,respectively. The authors mainly focused on the study of the influence of the East Asian summer monsoon on the summer precipitation in Shanxi Province. The result is valuable for both of the research and operation.

关 键 词：夏季风指数 降水异常 夏季风的建立和撤退 环流场异常 

分 类 号：P467[天文地球—大气科学及气象学]