简介：Temporalandspatialevolutioncharacteristicsofthe30-60dayoscillation(intraseasonaloscillation,ISO)ofsummerrainfallinChinaandtheeffectsofEastAsianmonsoonontherainfallISOareanalyzedinthispaper.Resultsshowthattheannualanddecadalvariationsoftheoscillationexistbetween1960and2008,andtheintensityisweakestinthelate1970sandearly1980s.InthetypicalstrongyearsoftherainfallISOobtainedfromempiricalorthogonalfunctions(EOFmode1),ananticycloneisinnorthwesternPacificandacycloneisintheeastofChina.Inthetypicalweakyears,thewindISOismuchweaker.Thelow-frequencyzonalwindandwatervaportransportfromthelowlatitudestomid-latitudesinthetypicalstrongyears,andtheoscillationstrengthofdiabaticheatingismuchstrongerthanthatintheweakyearsoftherainfallISO.TheanomalycharacteristicsoftherainfallISOshowanti-phasesbetweentheYangtzeRiverbasinandsouthofChina.AsforthetypicalstrongyearsoftherainfallISOintheYangtzeRiverbasin(EOFmode2),themainoscillationcenterofwatervaporisintheeastofChina(20-30°N,110-130°E).Inthepeak(break)phaseoftherainfalloscillation,alow-frequencycyclone(anticyclone)isintheYangtzeRiverbasinandananticyclone(cyclone)isnearTaiwanIsland.Inaddition,thepeakrainfallcorrespondstotheheatsourceintheYangtzeRiverbasinandtheheatsinkintheQinghai-TibetPlateau.AsforthetypicalstrongyearsoftherainfallISOinthesouthofChina,themainoscillationcenterofwatervaporissouthof20°N.Inthepeak(break)phaseoftherainfallISO,alow-frequencycyclone(anticyclone)isinthesouthofChinaandananticyclone(cyclone)isinthePhilippines.ThepeakrainfallcorrespondstotheheatsourceinthesouthofChinaandtheSouthChinaSea,andtheheatsinkinthewestofIndochina.

简介：Theatmosphericintraseasonaloscillation(ISO)anditsinterannualvariabilityaresimulatedbytheatmosphericgeneralcirculationmodel,whichwasdevelopedattheInstituteofAtmosphericPhysics.Twonumericalexperimentswereperformed,correspondingtotheAMIP-IandAMIP-IIsimulations,respectively.Themodelreasonablyreproducesthemajoraspectsoftheintraseasonaloscillation,includingthepropagatingpropertyandtheseasonaldifferencesinthetropics,thewavenumberstructureofISOintheglobe,andtheglobalcoincidenceintheinterannualvariationofISO.Comparisonoftheresultsbetweenthetwoexperimentssuggeststhatimprovementoftheboundaryforcingorconsideringtheair-seainteractionmayhelptoimprovethesimulationontheISOanditsinterannualvariability.

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简介：UsingtheECMWFreanalysisdaily200-hPawinddataduringthetwo20-yrperiodsfrom1958to1977andfrom1980to1999,thecharacteristicsandchangesofIntraseasonalOscillations(ISO)inthetwoperiodsassociatedwithglobalwarmingareanalyzedandcomparedinthisstudy.Itisfoundthatduringthelast20years,theISOhasweakenedinthecentralequatorialPacificOcean,butbecomesmoreactiveinthecentralIndianOceanandtheBayofBengal;underthebackgroundoftheglobalwarming,increaseintheamplitudeofISOintensitysuggeststhattheISOhasbecomemoreactivethanbefore,withanobviousseasonalcycle,i.e.,strongduringwinterandspring,butweakduringsummerandautumn;theenergyoftheuppertroposphericzonalwindshasmoreconcentratedinwavenumbers1-3,andthefrequencyofISOtendedtoincrease.ComparisonbetweentheresultsofcontrolexperimentandCO_2increase(1%peryear)experimentofFGOALS-1.0g(developedatLASG)withthefirstandsecond20-yrobservations,isalsoperformed.respectively.ThecomparativeresultsshowthatthespatialstructureoftheISOwaswellreproduced,butthestrengthofISOwasunderestimated.Onthebasisofspace-timespectralanalysis,itisfoundthatthesimulatedISOcontainstoomuchhighfrequencywaves,leadingtotheunderestimationofISOintensityduetothedispersionofISOenergy.However,FGOALS-1.0gcapturedthesalientfeaturesofISOundertheglobalwarmingbackgroundbytwocontrastexperiments,suchasthevitalityandfrequency-increasingofISOinthecentralIndianOceanandtheBayofBengal.

简介：宋玉成，黄荣辉ＴｈｅＤｙｎａｍｉｃａｌＥｆｆｅｃｔｓｏｆＤｉｖｅｒｇｅｎｔＷｉｎｄｏｎｔｈｅＩｎｔｒａｓｅａｓｏｎａｌｖａｒｉａｂｉｎｔｙｏｆｔｈｅＥａｓｔＡｓｉａｎＣｉｒｃｕｌａｔｉｏｎ￥ＳｏｎｇＹｕｃｈｅｎｇａｎｄＨｕａｎｇＲｏｎｇｈｕｉ（Ｉｎｓ...

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简介：Basedonobservationsandreanalysisdata,thecharacteristicsoftheevolutionofclimatologicalspringprecipitationoverSouthernChina(SPSC)andtheassociatedclimatologicalintraseasonaloscillation(CISO)andatmosphericcirculationarestudied.ResultsshowthatSPSCincreasesinanoscillatoryway.AlthoughtheevolutionofSPSCissimilarindifferentregions,therearealsodifferences.IndifferentregionsofSouthernChina,theonsetdatesoftherainseasonarefromthe12thto24thpentadandthepeakdatesareafterthe20thpentad.CISOisanimportantcomponentofSPSC,whichisnotonlystatisticallysignificant,butalsoaccompaniesadynamicallycoherentstructure.Thepeakwet/dryphaseofeachCISOcyclecorrespondstoasignificantrainfallincreasing/decreasingperiodandmodulatestheevolutionofSPSC.TherainfallgrowthinthesecondhalfofMarchandmid-Aprilistheresultofthemodulation.Thewet/dryphaseofCISOisaccompaniedbylow-levelconvergent(upper-leveldivergent)andcyclonic(anti-cyclonic)circulation,whichfavorsascendingmotiontodevelopoverSouthernChina.

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简介：BasedontheNCEP/NCARreanalysisIdailydatafrom1958to2002,climaticcharacteristicsofthe30-60-dayintraseasonaloscillations(ISOs)ofthezonalwind(u),meridionalwind(v),andgeopotentialheight(h)overglobalareasandespeciallytheISOofvoverthesubtropicalnorthernPacificareanalyzedusingthespace-timespectrumanalysisandwavelettransformmethods.TheresultsshowthattheISOofvisverydifferentfromthoseofuandh,withtheformerrepresentingthemeridionallow-frequencydisturbances,whicharethemostactiveinthesubtropicsandmid-highlatitudes,butveryweakinthetropics.InthesubtropicalNorthernHemisphere,theenergiesoftheISOsofuandharebothconcentratedonthewaveswithwavenumberof1andperiodsof30-60days,whilethemainenergyoftheISOofvisconcentratedonthewaveswithwavenumbersof4-6andperiodsof30-60and70-90days.Thewestwardpropagatingenergiesforthe30-60-dayoscillationsofu,v,andhareallstrongerthantheeastwardpropagatingenergiesinthesubtropics.Inaddition,theISOofvisthestrongest(weakest)insummer(winter)overthesubtropicsofEastAsiaandnorthwesternPacific,whilethesituationisreversedoverthesubtropicalnortheasternPacific,revealinga'seesaw'oftheISOintensitywithseasonsoverthesubtropicsfromthenorthwesterntonortheasternPacific.InthesubtropicalnorthwesternPacific,theinterannualandinterdecadalchangesoftheISOforvat850hPaindicatethatitsactivitiesaresignificantlystrongduring1958-1975,whileobviouslyweakduring1976-1990,andarethestrongestduring1991-2000,anditsspectralenergyisobviouslyabnormalbutrulelessduringtheENSOperiods.However,inthe2-7-yrbandpassfilteringseries,theinterannualchangesofthevISOoverthesubtropicalnorthwesternPacificcontaindistinctENSOsignals.Andinthe9-yrlow-passfilteringseries,thevISOchangesoverthesubtropicalnorthwesternPacificaresignificantlyoutofphasewiththechangesoftheNino-3.4SST,

简介：ＤＩＳＴＲＩＢＵＴＩＯＮＯＦＬＯＷＦＲＥＱＵＥＮＣＹＷＡＶＥＳＩＮＮＯＲＴＨＰＡＣＩＦＩＣＡＮＤＩＮＴＲＡＳＥＡＳＯＮＡＬＡＢＮＯＲＭＡＬＩＴＹＯＦＴＨＥＷＥＳＴＥＲＮＰＡＣＩＦＩＣＳＵＢＴＲＯＰＩＣＡＬＨＩＧＨＬｉＸｉｎｇｌｉａｎｇ（李兴亮）（Ｍｅ...

简介：我们在东亚(EA)上在夏天intraseasonal摆动(ISO)的27年的强迫的模拟评估GAMIL1.1.1的表演西方的诺思太平洋(WNP)。评价基于二项措施：climatologicalISO(CISO)和短暂ISO(TISO)。CISO是对年度周期锁阶段并且描述季节的行军的ISO部件。TISO是逐年变化的ISO部件。模型相当捕获ISO的许多观察特征，包括逐步向北方CISO的雨带进展，在华南海菲律宾的海(SCS-PS)和长江盆(YRB)的TISO的主导的频率，向北方3050天的TISO的繁殖并且向西在SCS-PS上的1225天的TISO模式的繁殖，和在YRB上的三个主要TISO模式的带的宣传特征。然而，模型有著名缺乏。这些包括与CISO联系的华南海季风的早发作，太快向北方到40°N和10°N的CISO信号南方的缺席的从20°N的CISO的繁殖，3050天的TISO模式的缺乏的东方繁殖和在YRBTISO模式的向南方的繁殖的缺席。作者发现在ISO模拟的缺乏是仔细与模型在平均数的偏爱有关说，建议模型的改进意味着状态为intraseasonal变化的现实主义的模拟是关键的。

简介：Inthispaper,five-yearsimulateddatafromalow-resolutionglobalspectralmodelwithtriangulartrunca-lionatwavenumber10areanalyzedinordertostudydynamicalfeaturesandpropagationcharacteristicsofintraseasonaloxillationsoverthemid-latitudesandthetropicalatmosphere.Thesimulationsshowthatthereisthe30-50dayperiodicoscillationinthelow-resolutionspectralmodelwithoutnon-seasonalexternalforcing,andspatialscaleoftheintraseasonaloscihationsisoftheglobe.Furtheranalysisfindsthatpropagationcharac-tersofintraseasonaloscillationsoverthemid-latitudesandthetropicsaredifferent.The30-50dayoscillationoverthetropicsexhibitsstructureofthevelocitypotentialwavewithwavenumber1inthelatitudinalandthecharacterofthetravelingwaveeastwardatspeedof8longitudes/day.However,the30-50dayoscillationsinmid-latitudeatmosphereexhibitphaseandamplitudeoscillationofthestandingplanetarywavesandtheyarerelatedtotransformofteleconnectionpatternsoverthemid-latitudes.Theenergyisnotonlytransferredbetweenthetropicsandthemiddle-highlatitudes,butalsobetweendifferentregionsoverthetropics.Basedontheanalysisof5-yearbandpassfiltereddatafroma5-layerglobalspectralmodelofJow-ordetwithtruncatedwavenumberl0,investigationisdoneofthesourceofintraseasonaloscillationsintheextratropicalmodelatmosphereanditsmechanism.Resultsshowthat(1)theconvectiveheattransferredeastwardalongtheequatorservesasthesourceoftheintraseasonaloxillationbothinthetropicalandtheextratropicalatmos--phere;(2)thevelocity-potentialwaveofazonalstructureofwavenumber1givesrisetooxillationindivergentandconvergentwindfieldsofadipole-formasseenfromtheequatorialIndianOceantothewesternPacificduringitseastwardpropagation,thusindicatingtheoscillationinthedipole-formheatsoure:e/sinkpattertl;(3)thetropicalheat-sourceoscillationisresponsibleforthe

简介：Theintraseasonaloscillation(ISO)isstudiedduringtheseverefloodanddroughtyearsoftheChangjiang-HuaiheRiverBasinwiththeNCEP/NCARreanalysisdataandtheprecipitationdatainChina.Theresultsshowthattheupper-level(200hPa)ISOpatternforsevereflood(drought)ischarac-terizedbyananticyclonic(cyclonic)circulationoverthesouthernTibetanPlateauandacyclonic(anti-cyclonic)circulationoverthenorthernTibetanPlateau.Thelower-level(850hPa)ISOpatternischar-acterizedbyananticyclonic(cyclonic)circulationovertheareasouthoftheChangjiangRiver,theSouthChinaSea,andtheWesternPacific,andacyclonic(anticyclonic)circulationfromtheareanorthoftheChangjiangRivertoJapan.Theselow-levelISOcirculationpatternsarethefirstmodesoftheISOwindfieldaccordingtothevectorEOFexpansionwithstrongeramplitudeoftheEOF1timecoefficientinse-verefloodyearsthaninseveredroughtyears.Theanalysesalsorevealthatat500hPaand200hPa,theatmosphericISOactivityovertheChangjiang-HuaiheRiverbasin,NorthChina,andthemiddle-highlatitudesnorthofChinaisstrongerforseverefloodthanforseveredrought.TheISOmeridionalwindoverthemiddle-highlatituderegionscanpropagatesouthwardsandmeetwiththenorthwardpropagatingISOmeridionalwindfromlowerlatituderegionsovertheChangjiang-HuaiheRiverBasinduringseverefloodyears,butnotduringseveredroughtyears.

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简介：Thestudypresentedhereininvestigatedthemaincharacteristicsofcarbonmonoxideintraseasonalvariabilityandevaluateditspossibleimpactfactorsusingtheuppertroposphereandlowerstratosphere(UT/LS)AuraMicrowaveLimbSounder(MLS)observationsoverTibetanPlateauanditsadjacentareasinsummer(JunetoAugust)of2005and2006.ObservationsshowapersistentconstituentextremeextendingupintotheUT/LSthroughoutsummer,aswellasatemporallyreversedphasevariationbetweenthecarbonmonoxideandozoneinUT/LS.Theintraseasonaloscillations(ISOs)ofcarbonmonoxideduringsummerareinvestigatedbyusingmethodsofwaveletandbandpassfilteranalysis.ItisfoundthatISOsovertheTibetanPlateauhaveperiodsof10to20daysand30to60days.Theformermainlyappearedinuppertropospherewhilethelatterinlowerstratosphere.FurtheranalysisshowsthatthesetwoperiodsofISOsinUT/LSaremainlyinphasetotheactivitiesofconvectionoverthesouthoftheplateauandthevariationofSouthAsiaHigh,respectively.TheabovetwofactorsandtheirdynamicalcouplingmayberesponsibleforthetracerISOsatdifferentlevels.

简介：Theimpactofstrong(weak)intraseasonaloscillation(ISO)overSouthChinaSea(SCS)andSouthAsia(SA)insummerontheSCSandSAsummermonsoonandthesummerrainfallinEasternChinaarestudiedbyusingtheNCEP-NCARanalysisdataandtherainfalldataof160stationsinChinafrom1961to2010.Itisfoundthattheimpactsaresignificantlydifferentindifferentmonthsofsummer.ThestudyshowsthatinJuneandJulycyclonic(anticyclonic)atmosphericcirculationoverSCSandSAcorrespondstostrong(weak)ISOoverSCS.InAugust,however,strong(weak)ISOoverSCSstillcorrespondstocyclonic(anticyclonic)atmosphericcirculationoverSA.InJuneandAugustcyclonic(anticyclonic)atmosphericcirculationoverSouthAsiacorrespondstostrong(weak)ISOoverSAwhileastrong(weak)ISOcorrespondstoanticyclonic(cyclonic)atmosphericcirculationoverSAinJuly.Besides,inJunethestrong(weak)ISOoverSAcorrespondstocyclonic(anticyclonic)atmosphericcirculationoverSCS,whileinJulyandAugusttheatmosphericcirculationisinthesamephaseregardlessofwhethertheISOoverSAisstrongorweak.Theimpactsofthestrong(weak)ISOoverSCSontherainfallofeasternChinaaresimilarinJuneandJuly,whichfavorsless(more)rainfallinYangtze-HuaiheRiversbasinbutsufficient(deficient)rainfallinthesouthofYangtzeRiver.However,theimpactsarenotsoapparentinAugust.InSouthAsia,thestrong(weak)ISOinJulyresultsinless(more)rainfallinthesouthofYangtzeRiverbutsufficient(deficient)rainfallinYangtze-HuaiheRiversbasin.TheinfluenceontherainfallineasternChinainJuneandAugustisnotassignificantasinJuly.

简介：BasedonthedailyprecipitationdataofninestationsrepresentingtheXijiangRivervalleyandtheNationalCenterforEnvironmentalPrediction/NationalCenterforAtmosphericResearch(USA)reanalysisdata,thisstudyusesthewaveletanalysisandband-passfiltermethodstoinvestigatetheatmosphericintraseasonaloscillationcharacteristicsofflood-causingrainstormsinthevalleyduringtheannuallyfirstrainingseasonsin1968,1994,1998,2002and2005.Resultsshowthatthedailyprecipitationinthevalleyexhibitssignificantquasi-biweekly(10to20days)oscillations.Theflood-causingrainstormsinthevalleyweremainlyassociatedwiththeconfluenceoflow-frequencywarmandhumidairflowinthelowerlatitudesandcoldanddryairflowinthehigherlatitudes.Thelow-frequencyvortexeswerepropagatingorincontrolwhenthistypeofrainstormstookplaceoverthevalley,beingfavorablefortheconvergenceofmoistureatlowerlevelsandthusvitaltotheformationoftherainstorms.