简介:Adiscrepancyremainsinthefirsttwoleadingempiricalorthogonalfunction(EOF)modesofthetropicalPacificseasurfacetemperatureanomaly(SSTA)basedonobservationssincethe1980s.TheEOF1mode,representingtheElNino-SouthernOscillation(ENSO),isarobustresult.However,theEOF2featureseitherElNinoModoki(EM)orENSOevolutionduringdifferentperiods,whichisprobablyassociatedwiththeimpactsofglobalwarming.TheunderlyingquestioniswhattheEOF2modeofthetropicalPacificwouldbewithoutglobalwarming.UsingtheCMIP5preindustrialscenariotoexcludetheinfluenceofglobalwarming,wefindthattheEOF1modeofthetropicalPacificSSTArepresentsENSOandthattheEOF2modeisnotEM.Accordingtothelead–lagcorrelationbetweentheENSOandEOF2modes,thelinkagebetweenthesetwomodesisasfollows:…ElNino→EOF2→LaNina→–EOF2→ElNino….Byanalyzingtheevolutionofseasurfacetemperature,surfacewind,andsubsurfaceoceantemperatureanomalies,wefindthemechanismlinkingtheENSOandEOF2modesistheair–seainteractionassociatedwiththeENSOcycle.ThisresultsuggeststhattheEOF2moderepresentsanaspectofENSOevolutionunderpreindustrialconditions.Therefore,thisstudyfurtherindicatesthattheEMisprobablyduetotheinfluenceofglobalwarming.
简介:Characteristicslipandcharacteristicearthquakemodelshavebeenproposedforseveraldecades.Suchmodelshavebeensupportedrecentlybyhigh-resolutionoffsetmeasurements.Thesemodelssuggestthatslipalongafaultrecursviasimilarlysized,largeearthquakes.Theinter-eventstrainaccumulationrate(ratioofearthquakeslipandprecedinginterseismictimeperiod)isusedheretotestthecharacteristicearthquakemodelbylinkingtheslipandtimingofpastearthquakesontheHaiyuanFault.Weaddresshowtheinter-eventstrainaccumulationratevariesovermultipleseismiccyclesbycombiningpaleoearthquakestudieswithhigh-resolutionairbornelightdetectionandranging(LiDAR)datatodocumentthetimingandsizeofpaleoearthquakedisplacementsalongthewesternandmiddlesegmentsoftheHaiyuanFault.Ourobservationsencompass5earthquakecycles.WefindsignificantvariationsovertimeandspacealongtheHaiyuanFault.WeobservethatonthemiddlesegmentoftheHaiyuanFaulttheratesslowdownorincreaseasananticorrelatedfunctionoftheratesofprecedingearthquakes.Here,weproposethattheinter-eventstrainaccumulationratesonthemiddlesegmentoftheHaiyuanFaultareoscillatingbothspatiallyandtemporally.However,alongthewesternsegment,theinter-eventstrainaccumulationrateisbothspatiallyandtemporallysteady,whichisinagreementwithquasi-periodicandslip-predictablemodels.Finally,weproposethatdifferentfaultsegmentswithinasinglefaultzonemaybehaveaccordingtodifferentearthquakemodels.