简介：Inthecontextof1980—1992JMA(JapanMeteorologicalAgency)GMSTBBgriddeddataset,studyisundertakenofannualcyclefeaturesofFFT-derivedwindowpowerspectrumaveragedovertherecordlength,withlocalizedspace/timecharacteristicsoflow-frequencyoscillation(LFO)inthetropicalatmosphereinvestigatedalongsidepossiblecauses.ItturnsoutthattheLFOtakesonsurprisinglynoticeableannualcyclefeaturesmarkedbyawidervariablerangeoftheLFOperiodsovernortherntropicsthanthesoutherncounterpartandequatorialvicinity.Inaddition,onthewhole,thesignalsaremoreintenseintheNorthernHemisphereduringsummer/autumnandatequatorial/southernlatitudeswhennorthernwinter/springoccuraswell.Also,notallthesefeaturesareidenticalfordifferentsegmentsatthesamelatitudes,displayingsignaturesonalocalbasis,andthespatial/temporallocalitycanbequalitativelyinterpretedintermsofnonlinearinteractionbetweentropicalwaves,andmodulationofdiabaticheatingontheLFOperiods.

简介：Basedonthewinter1984/1985ECMWFgridpointdatasubjectedtothe30-60dayband-passfilteringandcompositeanalysis,astudyisundertakenoftheLFO(low-frequencyoscillation)structureintheeasternAsianwesterlyjetentranceandexitregionsandtheAsia-Pacificlow-frequencyvortexactivitycharacteristics.Resultsshowthatzonalwindoscillationsonbothsidesofthejetcoreareinanti-phase,incloserelationtotheE-Wdisplacementofthecore.RanginginNW-SEdirectionisalow-frequencyvortextrain(LFVT)emanatingfromUralviacentralAsiatoEastAsia.Alow-frequencyvortexofUralorigin,whenreachingaround50(?),80(?),issplitintotwoparts,onetravellingeastwardandtheothersouthward,andfinallytheyarcconnectedcyclonicallyoranticyclonicallyatlowlatitudes,form-ingavigorouslowfrequencycycloneoranticycloneintheeasternpartofChinamainland,completingafullcycleoftheLFVT.Further,observedinthecentralPacificareameridionalLFVTandacyclone/anticyclonecoupletloopinginacounterclockwisesense,givingrisetotheLFVTphaseshiftoverthisregion.