长江、淮河梅雨期降水的时空变化特征及其成因比较.docx

长江、淮河梅雨期降水的时空变化特征及其成因比较
摘要
梅雨期是中国东部地区夏季降水的主要来源，对于该地区农业生产和生态环境具有重要意义。本文分析了长江、淮河流域梅雨期降水的时空变化特征，并探讨了其成因。研究结果表明，长江流域的梅雨期降水呈现出明显的南北分布差异，南部地区降水量大、降水期长、降水间隔短，北部地区则相反。淮河流域的梅雨期降水量总体呈现减少趋势，且降水期间偏移靠前。形成这些特征的主要因素包括环流、地形及气候变化等。
关键词：梅雨期、长江、淮河、时空变化、成因
Introduction
China'seasternregionischaracterizedbyasummerrainyseasonknownastheMeiyuperiod,whichisamajorsourceofprecipitationforthisregionandisofgreatsignificanceforagricultureandecologicalenvironment.TheMeiyuseasonextendsfromMaytoAugustandisdividedintothreestages:thepre-Meiyu,Meiyuandpost-Meiyuperiods.Inrecentyears,theMeiyuperiodhasexhibitedsignificantvariability,withchangesinbothitstemporaldistributionandspatialpatterns.
Inthispaper,weanalyzethetemporalandspatialvariabilityofMeiyuperiodprecipitationintheYangtzeandHuaiheRiverbasins,andexploretheunderlyingcausesofthesechanges.
TemporalvariabilityofMeiyuperiodprecipitation
TheMeiyuperiodprecipitationintheYangtzeRiverbasinshowsanincreasingtrendfromsouthtonorth.ThesouthernpartofthebasinexperiencesalongerMeiyuseason,higherrainfallintensity,andshorterintervalsbetweenrainfallevents.Conversely,thenorthernpartofthebasinhasashorterMeiyuseason,lowerrainfallintensity,andlongerintervalsbetweenrainfallevents.Thecentralpartofthebasinhasatransitionzonebetweenthesetworegions(Figure1).
Figure1.ThespatialdistributionofMeiyuperiodprecipitationintheYangtzeRiverbasinfrom1979to2013.
IntheHuaiheRiverbasin,theMeiyuperiodprecipitationshowsadecliningtrendfromwesttoeast,withthehighestrainfallinthewestandthelowestintheeast(Figure2).Overall,theMeiyuperiodprecipitationintheHuaiheRiverbasinhasdecreasedinrecentyears,particularlyintheeasternandcentralregions.
Figure2.ThespatialdistributionofMeiyuperiodprecipitationintheHuaiheRiverbasinfrom1961to2013.
SpatialvariabilityofMeiyuperiodprecipitation
ThespatialdistributionofMeiyuperiodprecipitationintheYangtzeRiverbasiniscloselyrelatedtothetopographyoftheregion.Themaritimemonsoonairmassfromthesouthisforcedtoascendoverthehighterraininthewesternpartofthebasin,leadingtoahighe