摘要
用夏季的月、季平均1 000 hPa位势高度场定义了一组描述印度低压的环流指数,包括:印度低压指数P、面积指数S、中心位置指数(λc,c)。用NCEP/NCAR再分析资料计算了1948—2008年逐年5—8月(用5,8月代表)、夏季(6—8月,用6,8月代表)印度低压的上述环流指数,用来分析夏季各月印度低压的气候和异常特征,并研究了P和λc指数与印度、中国同期降水的相关关系。分析结果表明:(1)印度低压5月形成后逐月西移、发展,7月达到最强(大)。(2)印度低压指数P和中心位置指数λc、c均存在显著年代际变化。P和c均在1960年代末发生年代际转变,它们的标准化距平P'(c')由负转正(由正转负),印度低压由强转弱(中心位置由偏北转偏南);λc'在1980年代以前为负,以偏西为主,之后转为偏东。(3)印度低压环流指数P、λc与印度同期降水显著相关,与中国同期降水也有一定相关。P与两国同期降水以负相关为主,即印度低压强年,两国某些地区降水异常增多;而λc与两国同期降水以正相关为主,即印度低压中心偏东,两国某些地区同期降水偏多;反之亦然。
A set of new circulation indices are defined to characterize monthly（^-5,8） and seasonal（ ^-6,8 ） average India low pressure on 1000 hPa geopotential height chart in summer, including area-（S′）, low pressure indices-（P） and center position-（λc,φc）. These indices, calculated by use of NCEP/NCAR data from 1948 to 2008 totalling sixty-one summers, are used to analyze the climatic and anomalous characteristics of the India low, and to investigate the relationship between the India low system and precipitation of India and China in summer, respectively. The results show that： （1） climatically, India low forms in May, then develops and moves westward month by month, and reaches the strongest in July. （2） there exist significant interdecadal variations for the indices（P） and center position （ λc,φc） of the India low pressure system. The P and % both exhibited inter-decadal change in 1960＇s with change of standardized departure p′ （φc′） from negative to positive （positive to negative）, corresponding to change of the India low pressure system from strong to weak one （centre position moving from north to south）. Meanwhile λc is negative, and dominated by westward position prior to 1980＇s, and changed into eastward afterward. （3） the India low circulation indices P and λc has a significant correlation with precipitation in India, but less in China in the same period. The P has dominantly negative correlation with precipitation in both countries in the same duration, i.e. the years with stronger India low pressure system correspond to abnormally increased precipitation.in some areas in bountries. However, the λc is primarily characterized by positive correlation with precipitation in the two countries in the same period, i.e. the more eastward than normal position of the India low system corresponds to more than normal precipitation in some areas in both countries in the same period. And vice versa
出处
《热带气象学报》
CSCD
北大核心
2011年第4期509-518,共10页
Journal of Tropical Meteorology
基金
江苏省研究生培养创新工程创新计划项目(CX08B_016Z)资助
关键词
大气环流
印度低压
环流指数
印度和中国夏季降水异常
： atmospheric circulation
India low pressure
circulation indices
summer precipitation anomaly in India and China
