Basedonobservationsandreanalysisdata,thecharacteristicsoftheevolutionofclimatologicalspringprecipitationoverSouthernChina(SPSC)andtheassociatedclimatologicalintraseasonaloscillation(CISO)andatmosphericcirculationarestudied.ResultsshowthatSPSCincreasesinanoscillatoryway.AlthoughtheevolutionofSPSCissimilarindifferentregions,therearealsodifferences.IndifferentregionsofSouthernChina,theonsetdatesoftherainseasonarefromthe12thto24thpentadandthepeakdatesareafterthe20thpentad.CISOisanimportantcomponentofSPSC,whichisnotonlystatisticallysignificant,butalsoaccompaniesadynamicallycoherentstructure.Thepeakwet/dryphaseofeachCISOcyclecorrespondstoasignificantrainfallincreasing/decreasingperiodandmodulatestheevolutionofSPSC.TherainfallgrowthinthesecondhalfofMarchandmid-Aprilistheresultofthemodulation.Thewet/dryphaseofCISOisaccompaniedbylow-levelconvergent(upper-levelpergent)andcyclonic(anti-cyclonic)circulation,whichfavorsascendingmotiontodevelopoverSouthernChina.
