简介：Thespring(March-April-May)rainfallovernorthernChina(SPRNC)ispredictedbyusingtheinterannualincrementapproach.DYdenotesthedifferencebetweenthecurrentyearandpreviousyears.TheseasonalforecastmodelfortheDYofSPRNCisconstructedbasedonthedatathataretakenfromthe1965-2002period(38years),inwhichsixpredictorsareavailablenolaterthanthecurrentmonthofFebruary.Thisisfavorablesothattheseasonalforecastscanbemadeonemonthahead.Then,SPRNCandthepercentageanomalyofSPRNCareobtainedbythepredictedDYofSPRNC.Themodelperformswellinthepredictionoftheinter-annualvariationoftheDYofSPRNCduring1965-2002,withacorrelationcoefficientbetweenthepredictedandobservedDYofSPRNCof0.87.Thisaccountsfor76%ofthetotalvariance,withalowvaluefortheaveragerootmeansquareerror(RMSE)of20%.Boththeresultsofthehindcastfortheperiodof2003-2010(eightyears)andthecross-validationtestfortheperiodof1965-2009(45years)illustratethegoodpredictioncapabilityofthemodel,withasmallmeanrelativeerrorof10%,anRMSEof17%andahighrateofcoherenceof87.5%forthehindcastsofthepercentageanomalyofSPRNC.

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