摘要
Fifty-eightextratropicaltransition(ET)casesintheyears2000-2008,including2,021observations(at6-hourintervals),overthewesternNorthPacificareanalyzedusingthecyclonephasespace(CPS)method,inanefforttogetthecharacteristicsofthestructureevolutionandenvironmentalconditionsoftropicalcyclones(TCs)duringEToverthisarea.ClusteranalysisoftheCPSdatasetshowsthatstrongTCsaremorelikelytoundergoET.ETbeginswiththeincrementofthermalasymmetryinTCs,alongwiththegenerationandintensificationofanupper-levelcoldcore,andendswiththeoccurrenceofalower-levelcoldcore.ETlastsanaveragedurationofabout28hours.Dynamiccompositeanalysisoftheenvironmentalfieldofdifferentclustersshowsthat,ingeneral,whenTCsmovenorthward,theyaregraduallyembeddedinthewesterliesandgraduallytransformintoextratropicalcyclonesundertheinfluenceofthemid-andhigher-latitudebaroclinicsystems.AsforthoseTCswhichcompleteET,thereisalwaysmuchgreaterpotentialvorticitygradientinthenorthwestofthemandobviouswatervaportransportchannelsintheenvironment.
出版日期
2017年01月11日(中国期刊网平台首次上网日期,不代表论文的发表时间)