简介:热带降雨测量的影响结构和intraseasonal摆动(ISO)的内在的物理上的使命(TRMM)降水产品与美国国家航空学和观察系统模型版本3的空格管理戈达德土(GEOS-3)被调查数据吸收系统(DAS)。在1998夏天的强壮的ISO阶段显然位于亚洲季风区域和东方赤道的和平的区域。当向东北的繁殖是在30点的突出的ISO到超过10的60天的摆动时,东方繁殖是为在20点的热带ISO的一个主导的特征到30天的摆动
简介:利用1°×1°的NCEP再分析资料、红外辐射亮温(TBB)、多普勒雷达和气柱水汽总量等资料,对2011年7月28-29日发生在山西境内的区域性暴雨进行多尺度特征分析。结果表明:(1)乌拉尔山阻高崩溃,西风槽东移、副高进退是此次暴雨发生的环流特征;(2)850hPa低涡切变和700hPa暖式切变线及地面冷锋是暴雨发生的中α尺度触发系统;(3)〉30dBZ的雷达回波呈南北向位于地面冷锋与700hPa切变线之间,雷达回波随地面冷锋和700hPa切变线的东移而东移;(4)低空低涡切变受500hPa强盛西南气流的引导向东北移动,暴雨落区始终与低涡切变相伴随;(5)暴雨过程山西境内共有9个中β尺度对流云团活动,山西西南部的暴雨主要由5个中β尺度对流云团的相继移入并在自动站极大风速风场切变线附近触发对流发展所致;山西东南部的大暴雨则是3个中β尺度对流云团合并发展的结果,中γ尺度气旋是导致局地大暴雨发生的直接影响系统;(6)暴雨发生在气柱水汽总量空间分布图中水汽锋的南部和东部及靠近气柱水汽总量的大值区一侧,水汽锋的形成比降水开始提前17h,比暴雨发生提前24h以上,对暴雨的短期、短时预报有指示意义。
简介:Dailysnowdatafor2300climatestationscoveringtheperiodfrom1951through1980havebeenusedtomonitoranddiagnosesecularvariations,year-to-yearfluctuations,andthespatialcharacteristicsofsnowvariationtrendsinChina.AnexaminationoftimeseriesrevealsthatthereisastrongteleconnctiontoENSO,tomajorvolcaniceruptions,aswellastotheCO2-inducedwarming.Thecountry-widesnowmassvariationsarepositivelycorrelatedwithglobalmeantemperature,increasingduringthecurrentwarmingperiodanddecreasingduringtherecentcoolingperiodpriortothemid1960s.AsynchronousrelationshipexistsbetweenElNino/SouthernOscillationandsnowywinterinChina.Theyear-to-yearsnowfluctuationsseemtobegenerallyoutofphasewithvolcanicactivity.Theanomalymapshowsthatsnowmassincreasedinhighaltitudesandmoistregions,whileitdecreasedinaridlowlandandthesouthernbounda-ryzoneduringthewarmingperiod.ThepotentialCO2-inducedchangesinsnowmasswillfurtheraggravatetheregionaldifferentiationbetweenhighmountainsandlowlands,betweenmoistandaridregions.Thenumberofsnowcoverdayswilldecreaseinthenorthernlowlands,andsnowfallwillincreaseintheQinghai-XizangPlateau,highmountains,andthelowerreachesoftheChangjiang(Yangtze)River.
简介:利用NCEP再分析资料和WRF模式,对2013年6月26—29日江西大范围暴雨过程进行了数值模拟分析。结果表明,西太平洋副热带高压脊线稳定维持在21°N附近,副高北侧强盛西南气流将水汽向江南北部地区输送是暴雨产生和稳定维持的主要原因。超低空偏南急流的建立、发展和维持是这次连续暴雨过程产生的一个重要因素,同时低空低涡南侧出现一串近似东西向排列的30~60km更小尺度的强对流系统,它们与大暴雨区相吻合;整层水汽通量密集区的南北界位置和暴雨区南北界位置基本吻合,整层水汽的大值中心的范围和大暴雨中心的范围具有明显的正相关关系;水汽通量散度最大辐合中心为暴雨的产生输送了大量的水汽,水汽辐合中心与暴雨的落区有很好的一致性;强降水落区与假相当位温最大值区相对应。
简介:Byusingtheupper-winddatafromJuly1980toJune1983,thevariationsofthelow-frequencyoscillation(LFO)intheatmospherebeforeandduring1982ElNinohavebeeninvestigated.BeforetheElNino,theLFOpropagatesfromwesttoeastovertheequatoroftheEasternHemisphereandfromeasttowestover20°N.TheeastwardpropagatingLFOovertheequatorconsistsofzonalwavenumber1propagatingeastwardandzonalwavenumber2withacharacterofstationarywave.Theoscillationofzonalwavenumber2canmodulatetheoscillationstrength.AftertheonsetoftheElNino,thepropagatingdirectionsoftheLFOovertheequatorand20°NoftheEasternHemispherechangetobewestwardandeastward,respectively.TheLFOoverthewesternPacificweakensrapidlyandonecomingfrommiddleandhighlatitudespropagatestotheequator.Fromthephasecompositionsofstreamlinefieldsforthezonalwavenumber1ofequatorialwestwardpropa-gatirgLFO,itisfoundthattheatmosphericheatsourceintheequatoroftheeasternPacific(EEP)excitesaseriesoftheequatorialcyclonesandanticycloneswhichmovenorthwardandwestwardandformthewestwardpropagatingLFOovertheequator.Withthewavelengthof20000km,thiskindofequatorialwaveissimilartothemixingRossby-gravitywave.Initswestwardandnorthwardmovement,thecirculationinEastAsiaismodified.ThismaybethemechanismoftheinfluenceofElNinoontheclimateofChina.
简介:AsimulationofclimatechangetrendsoverNorthChinainthepast50yearsandfuture30yearswasperformedwiththeactualgreenhousegasconcentrationandIPCCSRESB2scenarioconcentrationbyIAP/LASGGOALS4.0(GlobalOcean-Atmosphere-Landsystemcoupledmodel),developedbytheStateKeyLaboratoryofNumericalModellingforAtmosphericSciencesandGeophysicalFluidDynamics(LASG),InstituteofAtmosphericPhysics(IAP),ChineseAcademyofSciences(CAS).Inordertovalidatethemodel,themodernclimateduring1951-2000wasfirstsimulatedbytheGOALSmodelwiththeactualgreenhousegasconcentration,andthesimulationresultswerecomparedwithobserveddata.Thesimulationresultsbasicallyreproducethelowertemperaturefromthe1960stomid-19?0sandthewarmingfromthe1980sfortheglobeandNorthernHemisphere,andbettertheimportantcold(1950-1976)andwarm(1977-2000)periodsinthepast50yearsoverNorthChina.Thecorrelationcoefficientis0.34betweensimulationsandobservations(significantatamorethan0.05confidencelevel).TherangeofwintertemperaturedeparturesforNorthChinaisbetweenthosefortheeasternandwesternChina'sMainland.Meanwhile,thesummerprecipitationtrendturningaroundthe1980sisalsosuccessfullysimulated.Theclimatechangetrendsinthefuture30yearsweresimulatedwiththeCO_2concentrationunderIPCCSRES-B2emissionscenario.Theresultsshowthat,inthefuture30years,wintertemperaturewillkeepawarmingtrendinNorthChinaandincreasebyabout2.5℃relativetoclimatemean(1960-1990).Meanwhile,summerprecipitationwillobviouslyincreaseinNorthChinaanddecreaseinSouthChina,displayingasouth-deficit-north-excessivepatternofprecipitation.
简介:Abaroclinicsemi-geostrophicmodelwithevaporation-windfeedbackmechanism(EWFM)andCISKisestablished,twonon-dimensionalparametersaandηareintroducedtorepresentEWFMandCISK,respectively.Analyticsolutionsofthemodelsystemareobtained,dynamicsanalysesandthemodelatmospherecalculationsfurtherconfirmthatEWFMandCISKareveryimportantphysicalprocessesinleadingtothelow-frequencyoscillationsinthetropics.
简介:利用常规观测资料和MICAPS提供的相关资料,对2008年2月29日至3月1日在我区阿拉善盟、巴彦淖尔市西部、鄂尔多斯市西部发生的区域性沙尘暴天气的环流形势及物理量进行分析。分析表明:(1)本次沙尘暴过程基本属于蒙古气旋和干冷锋混合型,有利的气候背景是本次沙尘暴的基础。(2)影响这次沙尘暴天气的高空急流主要是250hPa附近的西风急流,较强西风急流通过动量下传引起地面大风,造成地面减压,促进了蒙古气旋的发展,从而促进了沙尘暴的发展。(3)在40~45°N,95~109°E整层强烈辐合、上升造成很强的抽吸作用可导致强烈辐合,在近地面形成大风和沙尘的扬起提供了较好的条件。
简介:Toaddtothegrowingmatureresearchonthetropical30-50dayoscillationsfromanewprospective,thecurrentworkbasesondynamicanalysisofbaroclinicquasi-geostrophicmodelstodiscussdynamicmechanismsforthegenerationandpropagationofCISK-Rossbywaves,andtounderstandrestraintsandeffectsofdifferentwavestructuresandthermodynamicforcingonthe30-50dayoscillationsinthetropicalatmosphere.Someimportantpropertiesoftheoscillationpropagationhavebeenexplainedand,indetail,withrespecttoitsmeridionalpropagationandvertical'baroclinic'structure.Theworkhascomeupwithsomenewopinionsandviewpoints.Newopinionsaboutthepropagationandenergydispersionaretobeprovedbymoreobservationsandstudy.