简介:AtmosphericInfraredSounder(AIRS)datashowthattheSaharanairlayer(SAL)isadry,warm,andwell-mixedlayerbetween950and500hPaoverthetropicalAtlantic,extendingwestwardfromtheAfricancoasttotheCaribbeanSea.TheformationsofbothHurricaneIsabelandTropicalDepression14(TD14)wereaccompaniedwithoutbreaksofSALairduringtheperiod1-12September2003,althoughTD14failedtodevelopintoanamedtropicalcyclone.TheinfluenceoftheSALontheirformationsisinvestigatedbyexaminingdatafromsatelliteobservationsandnumericalsimulations,inwhichAIRSdataareincorporatedintotheMM5modelthroughthenudgingtechnique.AnalysesoftheAIRSandsimulationdatasuggestthattheSALmayhaveplayedtworolesintheformationoftropicalcyclonesduringtheperiod1-12September2003.First,theoutbreaksofSALairon3and8Septemberenhancedthetransverse-verticalcirculationwiththerisingmotionalongthesouthernedgeoftheSALandthesinkingmotioninsidetheSAL,triggeringthedevelopmentoftwotropicaldisturbancesassociatedwithHurricaneIsabelandTD14.Second,inadditiontothereducedenvironmentalhumidityandenhancedstaticstabilityinthelowertroposphere,theSALdryairintrudedintotheinnerregionofthesetropicaldisturbancesastheircyclonic?owsbecamestrong.ThiseffectmayhavesloweddowntheformationofIsabelandinhibitedTD14becominganamedtropicalcyclone,whiletheenhancedverticalshearcontributedlittletotropicalcycloneformationduringthisperiod.The48-htrajectorycalculationsconfirmthattheparcelsfromtheSALcanbetransportedintotheinnerregionofanincipienttropicalcyclone.
简介:这研究调查了通过确定、概率的预报在华南在2007年4月23日与伪静止的前面联系的一根嚎啕线的可预测性。我们的结果证明嚎啕线模拟是很敏感的在物理parameterization计划从水平分辨率和无常为错误建模。至少一种10-km格子尺寸是必要的高雅地捕获这根嚎啕线。有4.5km的一种格子尺寸的模仿的嚎啕线对相对象微视物理学和行星的边界层那样的另外的物理计划的长波浪的放射parameterization计划很敏感。为从20~5km的一种格子尺寸,一个积云parameterization计划降级了嚎啕线模拟(相对关掉它),与到格子尺寸的更严重的降级<10km比>10km。到起始的错误的嚎啕线模拟的敏感通过整体预报被调查。嚎啕线的整体模拟的表演对起始的错误很敏感。约15%整体成员高雅地捕获了嚎啕线的进化,25%失败了,并且60%打乱了嚎啕线。用物理parameterization的不同联合,为不同成员的计划能改进概率的预报。这个案例的铅时间仅仅是一些小时。错误生长清楚地与潮湿的传送对流开发被联系。当起始的错误逐渐地被减少时,在嚎啕线模拟的性能的线性改进被观察,与来自起始的潮湿地的最大的贡献。
简介:SincethelastInternationalUnionofGeodesyandGeophysicsGeneralAssembly(2003),predictabilitystudiesinChinahavemadesignificantprogress.Fordynamicforecasts,twonovelapproachesofconditionalnonlinearoptimalperturbationandnonlinearlocalLyapunovexponentswereproposedtocopewiththepredictabilityproblemsofweatherandclimate,whicharesuperiortothecorrespondinglineartheory.Apossiblemechanismforthe'springpredictabilitybarrier'phenomenonfortheElNi(?)o-SouthernOscillation(ENSO)wasprovidedbasedonatheoreticalmodel.ToimprovetheforecastskillofanintermediatecoupledENSOmodel,anewinitializationschemewasdeveloped,anditsapplicabilitywasillustratedbyhindcastexperiments.Usingthereconstructionphasespacetheoryandthespatio-temporalseriespredictivemethod,Chinesescientistsalsoproposedanewapproachtoimprovedynamicalextendedrange(monthly)predictionandsuccessfullyappliedittothemonthly-scalepredictabilityofshort-termclimatevariations.Instatisticalforecasts,itwasfoundthattheeffectsofseasurfacetemperatureonprecipitationinChinahaveobviousspatialandtemporaldistributionfeatures,andthatsummerprecipitationpatternsovereastChinaarecloselyrelatedtothenorthernatmosphericcirculation.Forensembleforecasts,anewinitialperturbationmethodwasusedtoforecastheavyraininGuangdongandFujianProvinceson8June1998.Additionally,theensembleforecastapproachwasalsousedforthepredictionofatropicaltyphoons.Anewdownscalingmodelconsistingofdynamicalandstatisticalmethodswasprovidedtoimprovethepredictionofthemonthlymeanprecipitation.Thisnewdownsealingmodelshowedarelativelyhigherscorethantheissuedoperationalforecast.
简介:The12ththePacificAsianMarginalSeas(PAMS)/JapanandEastChinaSeaStudy(JECSS)(PAMS/JEC-SS)Workshopwasheldon22-24November2003inHangzhou,China.Morethan100scientistsattendedthisworkshop.Therewere57oralpresentationsand43postpresentations,groupedinto7themes,namely,(1)StudiesoftheSouthChinaSea(2)StudiesoftheBohai,HuanghaiandEastChinaSeas
简介:Radiosondeprofilesoftemperatureanddewpointtemperaturefromonestationareusedtoforecast12-hprecipita-tionoverNairobi,Kenya.Theforecastschemeisbasedonstatisticalregressionmodelling.Fourpredictorsarederivedfromdatatouseinaprognosticequationtoget12-hprecipitationforecast.Observedandpredictedrainfallvaluesareplottedonagraphagainsttime.Forecastverificationshowsthattheforecastsarepositivelycorrelatedwithobservations.
简介:High-frequencyruptureprocessoftheOct23,2011Van-Merkezearthquakeisimagedbyback-projectionmethodusinghigh-qualityteleseismicPwavedatafromtheUSArray,andprestackKirchhoffmigrationusingPwavedatafromasubarrayofglobalseismicnetworks.Therupturemodelwithtwoasperitiesisconfirmedbyprevioustwomethods.Inlow-frequencyimaging,alargeasperityderivedfromthemigrationmethodcorrespondstothesecondonefromthehigh-frequencyPwaves.Theconsistencyofthelocationsofasperitiesfromdatasetswithdifferentfrequencybandsindicatesthatthereispossibleinsignificanceofthefrequency-dependentfeaturefortheearthquake.Theresultantimagesillustratethespatialandtemporalevolutionoftherupture,whichmainlypropagatedWSWoveralengthof33kmduringthefirst18s,accompanyingwithburstsoftwoasperitiesat3and11–13s.TherupturedirectionisconfirmedbytheSwavecornerfrequencyvariationsofstronggroundaccelerations.Therupturefrontsaremainlylocatedattheupdipofthecausativefault.BasedonpolaritiesofthePwaveformsandfocalmechanismsofthemainshockandaftershocks,thefailureofthesetwoasperitiesisdeterminedtohaveoccurredonareversefaultwithadipangleof47°.Hence,therupturepatternofthe2011Van-Merkezearthquakewasdominatedbyaunilateralrupturetowardthewestsouthwestdirection.
简介:一、地震基本参数表1 地震基本参数表发震时间年月日时分秒震 中 位 置微 观宏 观东经北纬东经北纬参考地名震级(ML)震源深度(Km)震中烈度 地震类型 1978112305492591184°239°漳浦海外41Ⅴ主震型 注:震中位于海中,表中烈度为估计值。二、烈度分布本次地震震级不高,震中又位于海中,未造成任何破坏,但有感面积大。地震后,在厦门及漳州两地市区近海岸带的部分县城,乡镇所在地共24个点,走访600多人进行座谈形式的调查。调查均位于Ⅳ度烈度区内。地震时,室内大多数人有感觉,室外活动的人有感的较少,少数人从梦中惊醒。人们普遍感到床铺等在摇摆,听到玻璃窗在轻微作响。图6-1 1998