简介:Inthispaper,byusingspectralmethod,themonthly-andseasonal-scaleatmosphericdiabaticheatflow(ADHF)departurefieldsarediagnosedintheperiodof1964—1985with6ElNinoyearsand6anti-ElNinoyearsovertheNorthernhemisphere(NH).TheresultsshowthatElNinophenomenahavepronouncedinfluenceontheADHFdepar-turefields.Theresponseofatmosphereexhibitsapreferredarrangementoforganizingpositiveandnegativedeparturecentersatlow,middleandhighlatitudes.Inanti-ElNinoyears,theresponsehasthesameformsasinElNinoyears,butdeparturecentersareoppositeinphase.Furthermore,ADHFdepartureshowslow-frequencyoscillationinElNinoyearsandanti-ElNinoyears.ThecenterofdifferenceindeparturebetweenElNinoandanti-ElNinoyearsdisplaysabi-monthlyoscillation.Finally,throughair-seacorrelationanalysis,itispointedoutthattheSSTanomalyisthemostimportantcauseforADHFanomaly.
简介:利用40a(1961—2000年)的海温资料和同期NCEP资料以及高原51个测站的降水资料,探讨了赤道东太平洋平均海温增暖与青藏高原东部地区500hPa月平均高度的相关关系,以及在这种相关影响下气温、比湿和气流动能等的变化状态。结果表明:赤道东太平洋海温增暖(SSTA≥0.5℃)与青藏高原东部地区500hPa月平均高度场之间存在明显的滞后性相关关系,这种滞后性相关不但影响到高原高度场,还影响到气温、比湿和气流动能等,使高原500hPa气象场发生变化。同时这种变化又与高原东部地区表征旱涝状况的Z指数的时空分布有很好的对应关系,即当受影响的高度、气温、比湿增大及气流动能减小时,高原东部地区发生涝(多雨)的几率较大;当受影响的高度、气温、比湿减小及气流动能增大时,高原东部地区发生旱(少雨)的几率较大。
简介:Inthispaper,theconceptofstationary-wavenonstationarityispresentedandelucidatedintheframeworkoftheLorenzcirculationdecomposition.Thisconceptindicatestherelativemagnitudeofthezonalnonuniformabnormitytotheintensityofstationarywavesonthemonthlymeanscale.BasedontheLorenzcirculationdecomposition,thenonstationaritydegreeI_(us)(I_(us)~1)oftheglobal(local)stationarywavesisdefined,andthenusedtoanalyzethestationary-wavenonstationarityat30°-60°N,wheretheintensityofstationarywavesat500hPaintheNorthernHemisphere,asiswellknown,isveryhigh.Thefollowingfindingsareobtained:(1)Thereexistseasonalsouthwardandnorthwardmovementsinthepositionofthenonstationarityzonesoftheglobalstationarywaves.Thesteadystationarywavesoccurinmidlatitudes(35°-55°N)inwinterandinthesubtropicalregion(southof35°N)insummer,associatedwiththemajortroughsoverEastAsiaandNorthAmericaandtheweakEuropeantroughinwinter,andwiththerelativelysteadysubtropicalhighsysteminsummer.AhighvaluecenterofI_(us)isat35°Ninspringand50°Ninsummer,whichmightbecausedbytheseasonalvariationofstationary-waveintensity,particularlyinassociationwiththeinterannualvariabilityoftrough/ridgepositionsofstationarywavesonthemonthlymeanmaps.(2)ThereexistsobviousasymmetryinI_(us)~1,withthesteadyzonesalwayslocatedintheareascontrolledbystrongtroughs/ridgesandtheunsteadyonesintheareaswherethestationary-waveintensityislow.TheI_(us)~1inthesubtropics(southof35°N)islargerinwinterthaninsummer,andviceversainthemidlatituderegion(northof35°N).ThesummertimedistributionofI_(us)~1onthewholeshowsarathercomplicatedstructure.However,NorthEuropeisthemostunsteadyareaforlocalstationarywaves,asrepresentedbyhighvaluesofI_(us)~1inbothsummerandwinter,whileovertheNorthAmericancontinent(about120°E-60°W),theI_(us)~1isslightlylessthan1
简介:BasedonthetheoryofCanonicalCorrelationAnalysis(CCA),thecorrelationbetween500hPageopotentialheight(H)fieldsovertheNorthernHemisphere(NH)anda15-regionrainfall(R)fieldofChinainMayisstudied.Theresultsindicatethat:(1)thereisastrongrelationshipbetweentheHfieldsinJanuary/MayandtheRfieldinChina,(2)thevariationofthegeneralcirculationoverthewholeNH(especiallythe500hPaHfieldoverEuropeandAsia)canaffecttheRinChina,(3)inJanuaryandFebruarytheatmosphericgeneralcirculationcanaffecttheRmainlybymeansofplanetarywaves,whileinAprilandMaythemaincontrolmechanismcanbeduetosometeleconnections,and(4)thecharacteristicvectorsforRinMayandHfromJanuarytoMayhavewavetrainstructure,alternatingsignfromsouthtonorth.
简介:利用1961年以来宁夏冬季逐日气温资料及NCEP再分析资料和环流特征量资料,重点分析了21世纪以来宁夏冬季气温异常特征及同期500hPa环流变化特征。结果表明:冬季平均气温和最低气温极小值明显上升,夜间气温异常偏低日数显著减少,白天气温异常偏高日数显著增加,大部分地区夜间气温异常偏低日数减少趋势大于白天气温异常偏高日数的增加趋势。21世纪以来,易发生极端冷暖事件,异常偏高年份多于异常偏低年份。2007/2008冬季以后为1997年以来冬季平均气温偏低频率最高时段;冬季阶段性平均气温异常有4个特征:(1)气温异常主要出现在1月和2月;(2)异常偏低的幅度明显大于异常偏高的幅度;(3)相邻2旬间气温变化幅度增大;(4)最冷时段发生变化。从年代际变化看,冬季平均气温、最低气温极小值、白天气温异常偏高日数为最高或次高值,夜间异常偏低日数多为最低或次低值。500hPa高度上宁夏上空是影响冬季气温异常的关键区,其年代际及冷暖年强度变化是造成气温异常的最直接原因。宁夏冬季气温对亚洲西风环流指数和西太平洋副热带高压强度指数的响应更加敏感。
简介:用22年(1973~1994年)观测资料,由循环主振荡型分析(CSPOP)揭示了东半球500hPa环流、雪盖和中国降水量耦合系统的3~4年振荡的循环过程。结果表明,环流-冰雪-降水系统耦合振荡(ASRO)存在显著的欧亚太平洋(EUP)和中国东部型(EC)耦合移动波列,其中500hPa高度与雪盖波列空间位相相反,但一致向东南方向移动,而中国降水波列由北向南传播。这反映出欧亚雪盖异常影响欧亚大陆和海洋加热对比,并通过大气内部动力过程激发的耦合空间波的能量频散途径。
简介:利用1951—2004年全国160站降水资料和NCEP/NCAR500hPa月平均资料,从中纬度西风环流、位势高度、纬向风、经向风、垂直速度场等方面,分析了长江中下游地区6—7月降水与500hPa大气环流的关系。结果表明,欧亚中纬度地区西风带多雨、少雨年均表现为长波的两槽两脊形势,但是槽脊系统差异显著。长江中下游地区降水与东亚500hPa上空位势高度场、纬向风、经向风、垂直速度场均有显著的关系,进一步证明了长江中下游地区6—7月降水与500hPa大气环流有密切关系。
简介:Thelowlatitudeeasterliesat200hPainsummer(May-October)isanalysedclimaticallyduringthe13-yearperiodfrom1968to1980,withaspecialemphasisontherelationshipsbetweentheanomaloustropicaleasterlyjetStreamoverSouthAsiaandthelowlatitudeatmosphericcirculation,andalsothesummermonsoonprecipitationinIndia.ThecompositinganalysisshowsthatthetropicaleasterlyjetstreamoverSouthAsiahasfiveanomalouspatternsat200hPai.e.thewesternpattern,middlepattern,easternpattern,two-branchpatternandmulti-corepattern.EvidencehasshownthattheprecipitaioninIndiaanomalouslyincreasedduringtheanomalousperiodofthewesternpatternandthemiddlepattern,butreversecaseistrueintheeasternpattern.SomedifferentanomaliesoftheprecipitationindifferentareaofIndiawerefoundduringtheothertwoanomalouspattern.
简介:Thesynopticclimatologyofmonthlymeansurfaceairtemperatureanomaly(MMATA)at47surfacestationsinAsiaisassessedbytwotypesofmaps.ThefirstconsistsofsimplelinearcorrelationcoefficientsbetweentheMMATAatastationandthemonthlymean700hPaheightanomaly(MMHA)at134gridpointsintheNorthernHemisphere.Inwinter,thesefieldsgenerallycontaintwoequallyimportantcenters:acenterofmaximumpositivecorrelationapproximately1300kmfromthereferencestationandanegativecenterabout2800kmtoitsnorthwest.Insummer,thepositivecenterislocatedanaverageof800kmfromthereferencestationandstronglydominatestheMMATA,whilethenegativecenterisnolongerasimportantasinwinter.Thesecondkindofmapisaspecialtypeofanomalycomposite,constructedbymultiplyingthecorrelationcoefficientateachgridpointbythestandarddeviationofMMHAatthesamepoint.Thismapshowstheoptimumdistributionofheightanomaliesforabnormallywarm(orc
简介:目的:讨抑郁症的神经生物学发病机制,揭示针刺治疗抑郁症的机理。方法:以Wistar大鼠为受试对象,采用给予孤养大鼠以长期不可预见的中等强度刺激的方法建立抑郁大鼠模型,检测应激后造成的抑郁模型大鼠行为学改变、下丘脑垂体肾上腺皮质轴(HPA)的变化,同时观察针刺干预效应及不同针法的疗效比较。结果:型组、生理盐水组血清CORT和ACTH含量明显高于正常对照组(P〈0.05);手针治疗组、电针治疗组血清CORT和ACTH含量明显低于模型组(P〈0.05);药物组血清CORT和ACTH含量明显低于生理盐水组(P〈0.05):手针治疗组、电针治疗组、药物组比较差别无统计学意义。结论:刺百会、太冲具有较明显的抗抑郁效应,其机制可能与针刺对HPA轴的调整有关。