WepresentamodelforpredictingsummertimesurfaceairtemperatureinNortheastChina(NESSAT)usingayear-to-yearincrementalapproach.Thepredictedvalueforeachyear'sincreaseordecreaseofNESSATisaddedtotheobservedvaluewithinaparticularyeartoyieldthenetforecastNESSAT.Theseasonalforecastmodelfortheyear-to-yearincrementsofNESSATisconstructedbasedondatafrom1975-2007.Fivepredictorsareused:anindexforseaicecoverovertheEastSiberianSea,anindexforcentralPacifictropicalseasurfacetemperature,twohighlatitudecirculationindices,aswellasaNorthAmericanpressureindex.AllpredictorsareavailablebynolaterthanMarch,whichallowsforcompilationofaseasonalforecastwithatwo-monthleadtime.ThepredictionmodelaccuratelycapturestheinterannualvariationsofNESSATduring1977-2007withacorrelationcoefficientbetweenthepredictedandobservedNESSATof0.87(accountingfor76%oftotalvariance)andameanabsoluteerror(MAE)of0.3℃.Across-validationtestduring1977-2008demonstratesthatthemodelhasgoodpredictiveskill,withMAEof0.4℃andacorrelationcoefficientbetweenthepredictedandobservedNESSATof0.76.
