简介:TheNCEP/NCARIIdailymeanreanalysisdataandobservedprecipitationdataareemployedtoinvestigatethewestwardextensionofthewesternPacificsubtropicalhigh(WPSH)duringtheheavyrainperiodoverthesouthernChinainJune2005.Resultsshowthattheremayexistarelationshipbetweentheeast-westshiftoftheWPSHandtheprocessofasouthernChinaheavyrain.TheanalysisindicatesthattheverticalmotionintheWPSHareaismainlycausedbythelatentheatreleaseofmonsoonrainbeltsonitsnorthernandsouthernsides.TheverticalmotioncouldcausetheaccumulationofairmassinthecenterandwestoftheWPSH,whichleadstoitsstrengthening.TheappearanceofthenorthernandsouthernmonsoonrainbeltscouldnotonlyenhancetheWPSHbystrengtheningthedescendingdraft,butalsoexcitethedevelopmentofpositivevorticityandrestricttheWPSH'smovementinthenorth-southdirection.Moreover,theIndianmonsoonrainfalltothewestoftheWPSHmayexcitethedevelopmentofanticyclonicvorticityonitseasternside,whichleadstothewestwardextensionoftheWPSH.