广东大尺度大气水汽汇的年际及年代际变化特征

INTERANNUAL AND INTERDECADAL VARIATIONS OF LARGE-SCALE MOISTURE SINKS OVER GUANGDONG

关键词:  水汽汇  年际和年代际变化  广东

Key words:  moisture sinks  interannual and interdecadal variations  Guangdong

摘要:

用1958～2004年实测降雨量和NCEP/NCAR再分析资料,分析了广东地区大尺度水汽汇的年际和年代际变化特征及其与水汽通量变化的关系。结果表明,气候平均而言,广东春夏季大气向地面输送较多水资源,秋季地气间相互交换的水分相当,冬季由地面向大气输送较多的水资源。四季和年水汽汇的年际分量方差贡献均占主导地位,秋、冬季水汽汇的年际分量有约3年的显著周期。除了显著的年际分量外,冬、春季和年水汽汇的年代际分量方差贡献也较显著,占总方差的40%以上,以30多年的长周期变化为主,目前正处于由正位相向负位相转变的过渡期,预示今后广东有偏旱趋势。广东冬春季水汽汇的异常有显著的同相关系。另外,夏、秋季水汽汇的年代际分量有10～15年的显著周期。广东各季大气水汽汇偏强(弱)是由于从热带低纬输送到南海北部至华南地区的水汽增强(减弱),并伴随着水汽通量的辐合的增强(减弱)造成,但各季水汽通量异常分布型是有差别的。

Abstract:

The interannual and interdecadal variations of moisture sinks over Guangdong are discussed with the NCEP/NCAR reanalysis data and observed precipitation data from 1958 to 2004.The results indicate that climatically,the amount of precipitation is larger than that of evaporation in spring and summer.Precipitation and evaporation almost balance each other in autumn and the amount of evaporation is larger than that of precipitation in winter.The interannual signal dominates the variations of moisture sinks in all seasons in Guangdong with a period of three-year oscillation in autumn and winter.Remarkable interdecadal signal characterized by a period of three-decade oscillation can be identified for winter and spring from seasonally averaged moisture sink data and from annually moisture data,with variance percentage larger than 40%.This result indicates that Guangdong is at a transitional stage from positive anomalies to negative anomalies.The moisture sink anomalies in winter and ofllowing spring over Guangdong are usually in-phare.Besides,there exist periodic oscillations with periods of 10 to 15 years in summer and autumn.The positive(negative) anomalies of moisture sinks over Guangdong are due to the intensified(weakened) moisture from the tropical areas being transported to the Southern China,accompanied by an intensified(weakened) moisture convergence.