简介：Inthisstudy,weexaminealong-termincreasingtrendinsubtropicalpotentialvorticity(PV)intrusioneventsoverthePacificOceaninrelationtotheglobalmeantemperaturerise,basedonmultiplereanalysisdatasets.ThefrequencyofthePVintrusionsiscloselyrelatedtotheupper-troposphericequatorialwesterlyductandthesubtropicaljet(STJ).AnoverallstrengtheningofthewesterlyductandweakeningoftheSTJarefoundtobedrivenbythewarming-inducedstrengtheningofWalkercirculationandregionalchangesinHadleycirculationonmulti-decadaltimescale,leadingtoanincreaseinthePVintrusionfrequencyoverthetropics.Theresultsarerobustinalldatasets.Themulti-decadalstrengtheninginthePacificWalkercirculationisconsistentwiththeglobalmeantemperaturerise.Inthisway,thePVintrusionsarecorrelatedwiththewarmingrelatedglobalmeantemperuaterise.WhentheinterannualvariabilityofENSOisremovedfromtheintrusiontimeseries,thelong-termtrendinPVintrusionsduetoexternalforcingassociatedwithanthropogenicwarming(globalmeantemperaturerise)becomesclearer.Thelinkbetweentheglobalmeantemperatureriseandintrusionfrequencyisfurtherverifiedbyperformingacorrelationanalysisbetweenthetwo.Thesignificant(>95%)correlationcoefficientis0.85,0.94,0.84,0.83,and0.84forERA-40,ERA-Interim,NCEP-NCAR,JRA-55,andJRA-25,respectively.Thisunequivocallyindicatesthattheglobalmeantemperaturerisecanexplainaround69%–88%ofthevariancerelatedtothelong-termincreaseinPVintrusionfrequencyoverthePacificOcean.

简介：TheprojectionofChina'snear-andlong-termfutureclimateisrevisitedwithanew-generationstatisticallydownscaleddataset,NEX-GDDP(NASAEarthExchangeGlobalDailyDownscaledProjections).Thisdatasetpresentsahigh-resolutionseamlessclimateprojectionfrom1950to2100bycombiningobservationsandGCMresults,andremarkablyimprovesCMIP5hindcastsandprojectionsfromlargescaletoregional-to-localscaleswithanunchangedlong-termtrend.Threeaspectsaresignificantlyimproved:(1)theclimatologyinthepastascomparedagainsttheobservations;(2)morereliablenear-andlong-termprojections,withamodifiedrangeofabsolutevalueandreducedinter-modelspreadascomparedtoCMIP5GCMs;and(3)muchaddedvalueatregional-to-localscalescomparedtoGCMoutputs.NEX-GDDPhasgreatpotentialtobecomeawidely-usedhigh-resolutiondatasetandabenchmarkofmodernclimatechangefordiverseearthsciencecommunities.