摘要
基于美国国家大气中心的CAM3.0模式,设计3组数值试验,以研究春季印度洋偶极子(IOD)海表温度异常对东亚夏季风的影响及其可能机制。结果表明:在IOD正位相年,对印度洋关键海区的春季海表温度加入强迫后,同期夏季(6—8月)的东亚夏季风明显偏弱:副热带高压位置偏南,长江流域上升运动加强、降水偏多,南海地区下沉运动加强、降水偏少、南海季风偏弱。还从经向、纬向垂直环流圈角度分析了IOD对东亚夏季风的可能影响机制:IOD正位相年,在IOD正SSTA区域(热带西印度洋)的东侧大约75°E附近能激发出上升运动,而在IOD负SSTA区域(热带东印度洋)的东侧大约110°E附近出现下沉运动,从而构成一个完整的纬向垂直环流圈;110°E附近的下沉运动又可能通过经向垂直环流圈影响南海和东亚副热带地区,造成东亚经度上赤道地区为上升运动、南海地区为下沉运动、长江流域为上升运动的异常经圈环流,从而使得东亚夏季风(包括南海季风和东亚副热带季风)整体偏弱。
Based on the Community Atmosphere Model（CAM）3.0 model of the U.S.National Centers for Atmospheric Research,three groups of experiments were designed to investigate the effects of spring Indian Ocean Dipole（IOD） sea surface temperature anomaly（SSTA） in the Indian Ocean on the East Asian summer monsoon.Results showed that during the positive phase of IOD,the successive East Asian summer monsoon will be weakened significantly,with the subtropical high located south of its normal position,the ascending motion being stronger（weaker） and much more（less） rainfall over the Yangtze River Basin（South China Sea）.A possible mechanism for the above effects is also discussed by analysing the zonal and meridional vertical circulations.During the positive IOD phase,an ascending（decending） motion will be excited at about 75 °E（110 °E）,east of the area of positive（negative） SSTA,thereby forming a closed zonal vertical circulation.The decending motion at 110 °E will further exert influence on the meridional circulation in East Asia,resulting in ascending motion along the equator,decending motion over South China Sea,and ascending motion along the Yangtze River Basin,a situation of weakened East Asian monsoon.
出处
《热带气象学报》
CSCD
北大核心
2011年第5期703-709,共7页
Journal of Tropical Meteorology
基金
江苏省气象灾害重点实验室项目(KLME060210)资助
关键词
IOD
东亚季风
垂直环流圈
数值研究
IOD
East Asian Monsoon
Vertical Circulation
Numerical Study
