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:Radiosondeprofilesoftemperatureanddewpointtemperaturefromonestationareusedtoforecast12-hprecipita-tionoverNairobi,Kenya.Theforecastschemeisbasedonstatisticalregressionmodelling.Fourpredictorsarederivedfromdatatouseinaprognosticequationtoget12-hprecipitationforecast.Observedandpredictedrainfallvaluesareplottedonagraphagainsttime.Forecastverificationshowsthattheforecastsarepositivelycorrelatedwithobservations.
简介:RecentadvancesinthestudyofnonlinearatmosphericandclimatedynamicsinChina(2003-2006)arebrieflyreviewed.Majorachievementsinthefollowingeightareasarecovered:nonlinearerrordynamicsandpredictability;nonlinearanalysisofobservationaldata;eddy-forcedenvelopeRossbysolitontheory;sensitivityandstabilityoftheocean'sthermohalinecirculation;nonlinearwavedynamics;nonlinearanal-ysisonfluctuationsintheatmosphericboundarylayer;thebasicstructuresofatmosphericmotions;someapplicationsofvariationalmethods.
简介:自从2003,这篇论文考察中央规模天气动力学的主要理论进步,包括:(1)平衡并且失衡的流动的动态机制被使用学习中央规模循环的开始和发展问题。对称的不稳定性和横向波浪的不稳定性在线和旋涡空气传送对流被分析,并且进一步的研究在非线性的对流对称的不稳定性上被做了。在强迫对流和不稳定的传送对流和中央规模运动的波浪特征之间的相互作用也被讨论。(2)动态边界层建模的中间的空气被开发。复杂非线性的相互作用在大气的边界层和自由大气层之间理论上被分析。低级前面的地形学边界层和另外的边界层的结构动态问题被讨论。(3)在东亚空气发行量的背景下面的meso-β-scale暴风雨的形成和发展与MPV(潮湿的潜在的涡度)的变化被诊断异例。,并且在潮湿的空气。