TobetterunderstandclimatevariationsofMeiyu,somenewindicatorsfortheonsetandretreatdates,duration,andMeiyuprecipitationintheYangtze-HuaiheRivervalleyareobjectivelydevelopedbyusingobserveddailyprecipitationdatafrom230stationsineasternChinaduring1954-2003.Therainyseasononsetandretreatdatesineachstationcanbedefinedintermsofthresholdsforrainfallintensityandpersistence.Then,theonsetandretreatdatesoftheMeiyufortheYangtze-HuaiheRiverbasinhavebeendeterminedwhenmorethan40%ofstationsreachthefirstrainyseasonthresholdsinthestudyregion.BasedontheindicatorsofMeiyuintheYangtze-HuaiheRiverbasin,variationsofMeiyurainfallduring1954-2003areanalyzed.TheresultssuggestthatMeiyurainfallintheYangtze-HuaiheRiverbasinhasincreasedinrecent50years.Inaddition,interannualandinterdecadalvariabilityofMeiyuisalsoobvious.Alltheindicatorsdisplayapredominantperiodofabout3years.
