《Predictability of the East Asian Winter Monsoon Indices by the Coupled Models of ENSEMBLES》.pdf

ADVANCESIN ATMOSPHERIC SCIENCES．V0L．31．NOVEMBER2014．1279—1292 PredictabilityoftheEastAsianW interM onsoonIndicesby theCoupledM odelsofENSEM BLES Se—HwanYANGl，2andLU Riyu 1 StateKeyLaboratoryofNumericalModellingforAtmosphericSciencesandGeophysicalFluidDynamics InstituteofAtmosphericPhysics，ChineseAcademyofSciences，Beijing100029 UniversityofChineseAcademyofSciences，Beijing100049 (Received26January2014；revised2April2014；accepted20May2014) ABSTRACT TheseasonalpredictabilityofvariousEastAsianwintermonsoonrEAW M 1indiceswasinvestigatedinthisstudybased ontheretrospectiveforecastsofthefivestate．．of-the．．artcoupledmodelsfrom ENSEMBLESfora46．．yearperiodof1961- 2006．ItwasfoundthattheENSEMBLESmodelspredictfiveoutofthe21EAW M indiceswel1．withtemporalcorrelation coe币cientsrangingfrom 0．54to0．61．Thesefiveindicesaredefinedbytheaveraged1ower—troposphericwindsoverthe low latitudes(southof30。N)．Furtheranalysesindicatedthatthepredictabilityofthesefiveindicesoriginatesfrom their intimaterelationshiPwithENSO．Across—validatedprediction．whichtooktheprecedingfNovember)observedNifio3．4 indexasapredictor,givesapredictionskil1almostidenticaltothatshownbythemode1．Ontheotherhand．themodels presentratherlow predictabilityfortheotherindicesandofrsurfaceairtemperatureinEastAsia．Inaddition，themodels fai1toreproducetherelationshipbetweentheindicesofdifl~rentcategories．implyingthattheycannotcapturethetropical— extratropica1interactionrelatedtoEAWM vraiability．Together．theseresultssuggestthatreliablepredictionoftheEAW M indicesandEastAsianairtemperatureremainsachallenge． Keywords：EastAsianwintermonsoon，dynamicalindex，predictability，ENSO，ENSEMBL