摘要
Therelationshipbetweenthetropicalintra-seasonaloscillation(ISO)andtropicalcyclones(TCs)activitiesovertheSouthChinaSea(SCS)isinvestigatedbyutilizingtheNationalCentersforEnvironmentalPrediction/NationalCenterforAtmosphericResearch(NCEP/NCAR)globalreanalysisdataandtropicalcyclonebest-trackdatafrom1949to2009.Themainconclusionsare:(1)AnewISOindexisdesignedtodescribethetropicalISOactivityovertheSCS,whichcansimplyexpressISOforSCS.AfterexaminingtheapplicabilityoftheindexconstructedbytheClimatePredictionCenter(CPC),wefindthattheconvectionspatialscalereflectedbythisindexistoolargetocharacterizethesmall-scaleSCSandfailstodividetheTCsactivitiesovertheSCSintoactiveandinactivecategories.Consequently,theCPCindexcan’treplacethefunctionofthenewISOindex;(2)TheeastwardspreadprocessoftropicalISOisdividedintoeightphasesusingthenewISOindex,thephasevariationofwhichcorrespondswellwiththeTCsactivitiesovertheSCS.TCsgenerationandlandingaresignificantlyreducedduringinactiveperiod(phase4-6)relativetothatduringactiveperiod(phase7-3);(3)ThecompositeanalysesindicatedistinctTCsactivitiesovertheSCS,whichisconsistentwiththeconcomitantpropagationoftheISOconvectiveactivity.DuringISOactiveperiod,theweathersituationsarefavorableforTCsdevelopmentovertheSCS,e.g.,strongconvection,cyclonicshearandweaksubtropicalhigh,andviceversa;(4)Thecondensationheatingcenters,strongconvectionandwatervaporfluxdivergencearewellcollocatedwitheachotherduringISOactiveperiod.Inaddition,theverticalprofileofcondensationheatindicatesstrongascendingmotionandmiddle-levelheatingovertheSCSduringactiveperiod,andviceversa.Thus,theeastwardpropagationoftropicalISOiscapabletomodulateTCsactivitiesbyaffectingtheheatingconfigurationovertheSCS.
出版日期
2016年03月13日(中国Betway体育网页登陆平台首次上网日期,不代表论文的发表时间)