学科分类
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47 个结果
  • 简介:这研究在中国调查在夏天降雨之间的统计连接,使用欧亚的融雪水等价物(SWE)驻扎的从513的夏天降雨观察的数据集并且在在从1979~2004的时期期间的NCEP/NCAR分析的前面的春天,观察卫星的融雪水等价物,和大气循环变量。开始的二个联合模式被使用单个价值分解(SVD)识别方法。春天SWE可变性的领先的SVD模式在西藏的高原和东亚的一些小区域与相反的异例在大多数欧亚大陆显示出协调负异常。模式显示强壮内部年度可变性,迭加在上一内部发生在1980年代末的十的变化,与坚持的否定阶段在19791987并且经常的积极阶段以后。当领先的模式在它的积极阶段时,它在整个大多数欧亚大陆在春天对应于更少的SWE。同时,在西藏的高原和东亚,在南方的夏天降雨和东南中国的一些小区域的过多的SWE趋于被增加,而它将在黄河的起来到达被减少。在里面最近二十年,在欧亚大陆的减少的春天SWE可以在南方和东南中国是为在诺思和东北中国和更多重要降雨事件的严重干旱的原因之一。春天SWE可变性的第二个SVD模式在西方、东方的欧亚大陆出现在空间变化对面,当大多数西藏的高原和东亚在阶段时。这个模式显著地在诺思和东北中国与成功的夏天降雨相关,少些也就是说在东方欧亚大陆和西藏的高原在西方的欧亚大陆和过多的SWE触发SWE趋于在诺思和东北中国与减少的夏天降雨被联系。

  • 标签: 欧亚积雪异常分布 冬季 大气环流 影响
  • 简介:Landscapeecologyandlandscapepatternanalysisareimportantcomponentsofnational-scaleprogramstoidentifytrendsinlandcoverchangebecause:1)Statisticsonchangesinlandcoverproportionsarenotspatial.AchangematrixderivedfromGISprovidesusefulinformation,butitdoesnotshowthespatialformofchangeinthelandscape.Landscapepatternmetricsrevealspatialpattern.2)Agrowingbodyofliteraturehasshownthatachangeinlandscapepatternmightindicateimportantchangesinecologicalfunctions:forestconnectivityandspeciesmovements,numberandsizeoffarmpatches,effectsonwaterquality.Spatialpatternisimportantinstructuringecologicalcommunitiesandinmaintainingexistenceofcompetitors.Spatialpatternmaybedeterminedbydisturbanceandmayinturn,determinehowdisturbancespropagatethroughthesystem.3)Sometimeslandscapepatternmaynotsignificantlychange,eventhoughlandcoverproportionsdochange.Or,vice-versa,sometimeslandscapepatterncansignificantlychange,eventhoughlandcoverproportionsdon'tsignificantlychange.4)Landscapepatternisaninherentandimportantpartofdescribinglandscapes:basedontheliterature,oneofthemostimportantdescriptivecharacteristicsofalandscapeisitstexture.Theobjectivesofthispaperareto:1)Explaintheimportanceoftheroleoflandscapeecologyandlandscapepatternanalysisinlandcoverchangestudies;2)Reviewtheliteraturethatspecificallyincorporateslandscapeecologyintolandcoverchangestudies;and3)Listthetheoreticalandtechnicalissuesinvolvedandsuggestsolutionsforthem.

  • 标签: 土地覆被变化 景观类型分析 生态学 比例 GIS
  • 简介:CLOSINGHILLSFORREFORESTTION──AnEffectiveWaytoRestoreandIncreaseForestryPlantCoverTo“closehills”(sandplots,shoals)andallownatu...

  • 标签: CLOS
  • 简介:植被盖子在土壤在水流动上有主要效果。二个地点,由大约50m的距离分开了,被选择确定hydrophysical参数和在出现在一个大雨追随者期间的沙的土壤的水流动的异质上的草盖子的影响一个长热的、干燥时期。有植被或有机物的有限影响的控制土壤(纯沙)被采样在一个森林中的空地区域下面在50厘米深度获得,并且草地土壤在10厘米被盖住由草的厚腐殖的层和colonised。水抵抗性的坚持用微型磁盘infiltrometer用水落下穿入时间测试,sorptivity和不饱和的水力的电导率被测量,并且浸透用双戒指infiltrometer的水力的电导率。染料tracer实验被用来估计水流动,和两个的异质为估计有效的生气的节的修改方法和为估计优先的流动的度的一个原来的方法被用来确定从染的土壤的图象的这异质介绍。大多数hydrophysical参数在二表面之间是实质地不同的。草地土壤有水抵抗性的一个索引大约10次纯沙和水抵抗性的坚持的乘纯沙的的几乎350。分别地,在草地土壤的水和乙醇sorptivities纯沙的那些是7%和43%。在草地土壤的水力的电导率和浸透的水力的传导性分别地是纯沙的5%那些和16%。染料tracer实验与“air-draining”揭示了稳定的流动在纯沙的状况和在草地土壤的开发得好的优先的流动,相应于单个草丛、小微消沉。草地土壤是实质地,更多流水讨厌、有3与纯沙相比预定优先的流动的度。这研究的结果增强我们在气候的任何变化的后果,将最终影响水文学,将在草地和赤裸的土壤之间是显著地不同的看法。

  • 标签: 沙质土壤 植被覆盖 水流量 异质性 水力传导率 草地土壤
  • 简介:陆地使用和陆地盖子变化(LULCC)强烈由联合生物化学、生物物理的过程影响地区性、全球的气候。然而,生物物理的过程经常被忽略,它可以抵消biogeochemical效果,因此到地址气候变化的措施不能到达目标。因此,LULCC的生物物理的影响为观察气候以后在过去和潜在的情形改变的理解是批评的。因此,鉴别气候上的大规模LULCC的机制和效果通过改变内在的表面变化是必要的,并且这样精力平衡。在必须被探讨包括的全球气候上理解人的活动的影响上的关键科学问题:(1)在中国和比较国家的LULCC的空间、时间的变化的基本科学事实是什么?(2)怎么理解联合在LULCC上然后到预报未来情形驾驶人的活动和气候变化的机制?(3)LULCC的科学机制是什么,在陆地表面,然后气候的生物物理的过程上影响吗?(4)怎么估计到气候的LULCC的贡献由影响土地的生物物理的过程变化出现?由国际比较,在本地、地区性、全球的规模的气候变化上的LULCC的影响被揭示并且评估。它能为全球变化提供理论基础,并且有大意义减轻并且适应全球气候变化。

  • 标签: 土地覆盖变化 土地利用变化 气候影响 气候变化影响 生物地球化学 全球气候变化
  • 简介:土壤侵蚀是对我们的陆上的生态系统和一个重要全球环境问题的主要威胁。在中国的黄土高原是承受了在过去的十年温暖并且弄干的更严重的土壤侵蚀和经历的气候的区域之一。命名Grain-to-Green节目现在一直在操作超过10年了的植被恢复。估计土壤侵蚀的变化和降水和植被恢复的反应在黄土高原上玷污侵蚀是必要的。在学习,修订通用土壤损失方程(RUSLE)被使用评估走水路引起侵蚀的年度土壤损失。结果如下出现了。在2000和2010之间的黄土高原上的土壤侵蚀为15.2thm2a1平均并且为价值作为光被描绘不到25thm2a1。比25thm2a1高的严重土壤侵蚀主要在溪谷和多山的区域被散布在中央,西南,并且黄土高原上的地球岩石的多山的区域的一些散布区域。黄土高原上的土壤侵蚀在最近的十年显示出一个死亡趋势并且以率减少了更多在承受严重土壤损失的区域的超过1thm2a1。得益于改进植被盖子和生态的建设,黄土高原上的土壤侵蚀显著地被拒绝特别在Yulin的东方,最在山西省在Luliang和Linfen府的Shaanxi省,和西方Yanan府分开在多山并且溪谷区域。植被盖子反应在这些区域玷污侵蚀的变化比降水显示出相对更高的贡献。然而,在在Gansu省的Qingyang和Dingxi府和在NingxiaHui自治区域的Guyuan的大多数区域是主要与降水有关。

  • 标签: 中国黄土高原 土壤侵蚀 植被变化 降水 通用土壤流失方程 宁夏回族自治区
  • 简介:这研究在秋天和大气的发行量变化的影响分析北欧亚的雪盖子(SC)的可变性。大SC可变性的区域从9月显示向南方的移动到11月,跟随表面空气温度的转变地区的季节的前进(坐)。在9月和10月的SC可变性的主导的模式展示带的分布,并且那在11月显示一个明显的西方东方对比。表面空气冷却和降雪增加是为更大的SC的二个因素。相对贡献坐并且的降雪变化然而,SC与这个区域变化并且取决于季节。向下,longwave放射和大气的热移流在容纳的变化起重要作用。水蒸汽流动的异常集中贡献提高的降雪。变化在向下,longwave放射在大气的水内容和列厚度与那些被联系。在降雪和大气的潮湿的运输的变化决定在9月和10月的大气的潮湿内容,和降雪看起来是为在11月的大气的潮湿变化的一个主要因素。这些结果显示大气的发行量变化在秋天在北欧亚大陆上在雪可变性起一个重要作用。总的来说,在秋天之间联合欧亚的雪和大气的循环不能被外部强迫驾驶。

  • 标签: 大气环流变化 积雪变化 秋季 欧亚大陆 长波辐射 降雪量
  • 简介:ThecalculatingschemesofunderlyingsurfaceprocessesinthemodeldescribedbyLietal.(1989)aremodifiedwithinclusionofsimplelandsurfaceprocessesandoceanicmixedlayerprocesses,thenasimulationonthezonalwindalong90°EfromtheNortherntotheSouthernHemispherewithmoun-tainsisperformed.Comparisonsoftheresultsandtheobservationsshowthatthemodifiedmodelnotonlyhasanexcellentstabilityincalculationbutalsocanbetterdisplaytheseasonalchangeofthewindfield,theabilityofthepresentmodelisimprovedascomparedwiththatofthepreviousone.Basedonthesimulations,theauthorsinvestigatetheeffectsofQinghai-XizangPlateausnowcoverontheformationofSouthAsianmonsoonbythickcningthesnowdepthandbyincreasingthesnowalbedo.Themainresultsarcasfollows:ThesummermeridionalcirculationoverthesouthofthePlateauanditsvicinityisweakeued,andtheprecipitationreduced.However,overthenortherntropics,thecirculationisenhanced,andtheecipitationisincreased,andthelandandtheairaboveitbecomewarmer,thetropicaleasterlyjetisweakened.

  • 标签: UNDERLYING surface process MONSOON QINGHAI-XIZANG PLATEAU
  • 简介:StudyofseismicactivityintheKuqaareaenablesustoinfersomepossibleactivefaultsinbasementfromtheePicentraldistributionondifferentprofiles.Therelationsbetweenactivefaultsinthebasementandsurfacestructuresareanalyzedandthedifferencebetweensedimentarycoverandbasementintheirdeformationcharacteristicsandthegenesisarediscussed.Thefollowingconclusionshavebeendrawn:(1)theepicentraldistributionindicatesthat,theeastQiulitagandsouthandnorthQiulitagdeepfaultsinthebasementcorrespondtotheeastandwestQiulitaganticlines,respectively.Moreover,deepfaultsalsoexistbeneaththeYiqiklikandYakenanticlines.Itindicatesthattheformationofsurfacestructuresiscontrolledbydeepstructures;(2)ANE-trendingstrike-slipfaultdevelopsalongthelinefromthewesternterminationofYiqiklikstructuretoDongqiuWell5andaNW-trendingactivefaultonthewesternsideofBaicheng.ThetwoactivefaultsacrossthetectonicstrikearethemaincausesfortectonicsegmentationoftheKuqadepressionandpossiblythecauseforthemiddlesegment(Kuqa-Baicheng)ofthedepressiontobemoreshortenedthanbothitseasternandwesternterminations;(3)Thedifferencebetweenthesedimentarycoverandbasementintheirdeformationcharacteristicsdependsmainlyonthedifferentpropertiesofmediabetweenthem.Thelithosphericstrengthofthebasementinthebasinisfairlyhigh,whichdeterminesthebasementdeformationtobemainlyofbrittlefractureseismicactivity.Whilethestrengthofsedimentarycoverislow,wherethereexistweakthinlayers,suchascoalandgyps.Undertheeffectofstrongtectoniccompression,thesedimentaryrocksmayundergostrongviscousorplasticflowdeformation;meanwhile,anaseismicdetachmentmaytakeplacealongtheweaklayers.

  • 标签: 地震构造信息 沉积盖层 表面结构 变形特征 基岩断层
  • 简介:Byusingathree-levelatmosphericgeneralcirculationmodel(AGCM),wehavecompletedseveralnumericalexperimentstostudytheimpactsofseasurfacetemperatureanomaly(SSTA)andantarcticicecoveranomaly(AICA)during1981—1983onclimatevariability.TheresultsshowthatduringtheElNinoperiodof1982—1983theimpactofSSTAoverridesthatofAICA.SSTAmainlyaffectsequatorialzonalcirculationandproducesPNAwavetrain,andSE-NWwavetraininEastAsiatoinfluencetheweatherofChina.AICAproduceswest-eastanomalousvortexstreetsinthemiddlelatitudesofbothhemispheresandaffectstheintensityofthepolarvortexofSouthernHemisphere.

  • 标签: El Nino ANTARCTIC ice cover anomaly(AICA)
  • 简介:人的活动导致了生态系统,新热带区的干燥森林在之中是一些威胁的大多数的全球简化。产地损失以及边效果可以影响昆虫社区。这里,我们分析了在9处风景与平底锅陷井取样的昆虫(在5规模,在100-500m,直径盘旋)包括栽培了地和ChacoSerrano森林,在全面社区和分类顺序水平。在总数7043,标本和昆虫的456种类被捕获,与是的丰富和丰富直接与森林内部比较在边在500m并且更高与森林有关盖住。社区作文也与森林盖子和边/内部地点变化了。不同回答在8份主导的订单之中被检测。Collembola,半翅类,和直翅目丰富或丰富是断然在更大的规模与森林有关盖住,当Thysanoptera丰富仅仅在边与森林盖子增加了时。Hymenoptera丰富和丰富是否定地与在100m的森林盖子有关。翘目,双翅目,并且Hymenoptera在森林边更多样、丰富。昆虫社区上的森林损失的通常否定的影响能为自然、栽培的系统有功能的后果,并且加亮森林保存的关联。在边的更高的差异能源于森林和矩阵种类的同时的存在,尽管资源印射可能为更富有的订单和在边丰富的更多被包含。自从生来的敌人,邻近的庄稼能得益于森林最近,pollinators很好在显示出积极的边效果的订单被代表。

  • 标签: 森林覆盖率 昆虫群落 边缘效应 订单 植被覆盖 反应
  • 简介:Basedonaseriesofexperimentsunderbothice-coveredandfreesurfaceconditions,thepresentarticlediscussestheroleofflowvelocityandcriticalshearReynoldsnumberforincipientmotionofbedmaterial.Theinfluenceoftheresistancecoefficientsofboththeundersideoftheicecoverandthechannelbedonthelocationofthemaximumvelocityhasbeendiscussed.Inaddition,theimpactsoficeandcompositeresistancecoefficientsonflowvelocityforincipientmotionofbedmaterialhavebeenassessed.ThediagramdescribingthecriticalshearReynoldsnumberandthedimensionlessshearstressfortheincipientmotionofsedimentundericecoveredconditionswithdifferentundercoverresistancecoefficienthasbeenestablished.TheeffectsofgrainsizeondensimetricFroudenumberforincipientmotionofbedmaterialhavebeeninvestigated.ArelationshipbetweenthedensimetricFroudenumberforincipientmotionofbedmaterialandthemediangrainsizeofbedmaterialaswellastheroughnesscoefficientofchannelbedandroughnesscoefficientoficecoverhasbeenestablished.

  • 标签: 粒度 冰覆盖量 原始运动 电阻率
  • 简介:Thepaperpresentsthreeformalprovingmethodsforgeneralizedweaklygroundterminatingproperty,i.e.,weaklyterminatingpropertyinarestricteddomainofatermrewritingsystem,onewithstructuralinduction,onewithcover-setinduction,andthethirdwithoutinduction,anddescribestheirmechanizationbasedonameta-computationmodelfortermrewritingsystems-dynamictermrewritingcalculus.Themethodscanbeappliedtonon-terminating,nonconfluentand/ornon-left-lineartermrewritingsystems.Theycando"forwardproving"byapplyingpropositionsintheproof,aswellas"backwardproving"bydiscoveringlemmasduringtheproof.

  • 标签: 内存驱留程序 文件系统 TRS 计算机
  • 简介:Remote-sensingdataforprotectedareasinnorthernTogo,obtainedinthreedifferentyears(2007,2000,and1987),wereusedtoassessandmapchangesinlandcoverandlanduseforthisdroughtpronezone.Thenormalizeddifferencevegetationindex(NDVI)wasappliedtotheimagestomapchangesinvegetation.Anunsupervisedclassification,followedbyclassesrecoding,filtering,identifications,areacomputingandpost-classificationprocesswereappliedtothecompositeofthethreeyearsofNDVIimages.Maximumlikelihoodclassificationwasappliedtothe2007image(ETM+2007)usingasupervisedclassificationprocess.Sevenvegetationclassesweredefinedfromtrainingdatasets.Thesevenclassesincludedthefollowingbiomes:riparianforest,dryforest,floodedvegetation,woodedsavanna,fallows,parkland,andwater.Fortheseclasses,theoverallaccuracyandtheoverallkappastatisticfortheclassifiedmapwere72.5%and0.67,respectively.Dataanalysesindicatedagreatchangeinlandresources;especiallybetween1987and2000probablyduetotheimpactofdemocratizationprocesssocial,economic,andpoliticaldisorderfrom1990.Wide-scalelossofvegetationoccurredduringthisperiod.However,areasofvegetationclearingandregrowthweremorevisiblebetween2000and2007.Themainsourceofconfusioninthecontingencymatrixwasduetoheterogeneitywithincertainclasses.Itcouldalsobeduetospectralhomogeneityamongtheclasses.Thisresearchprovidesabaselineforfutureecologicallandscaperesearchandforthenextmanagementprograminthearea.

  • 标签: 土地覆盖变化 土地利用 保护区 遥感监测 归一化植被指数 植被变化
  • 简介:WemappedtheforestcoverofKhadimnagarNationalPark(KNP)ofSylhetForestDivisionandestimatedforestchangeoveraperiodof22years(1988-2010)usingLandsatTMimagesandotherGISdata.SupervisedclassificationandNormalizedDifferenceVegetationIndex(NDVI)imageclassificationapproacheswereappliedtotheimagestoproducethreecoverclasses,viz.denseforest,mediumdenseforest,andbareland.Thechangemapwasproducedbydifferencingclassifiedimageriesof1988and2010asbeforeimageandafterimage,respectively,inERDASIMAGINE.Errormatrixandkappastatisticswereusedtoassesstheaccuracyoftheproducedmaps.Overallmapaccuraciesresultingfromsupervisedclassificationof1988and2010imagerieswere84.6%(Kappa0.75)and87.5%(Kappa0.80),respectively.Forestcoverstatisticsresultingfromsupervisedclassificationshowedthatdenseforestandbarelanddeclinedfrom526ha(67%)to417ha(59%)and105ha(13%)to8ha(1%),respectively,whereasmediumdenseforestincreasedfrom155ha(20%)to317ha(40%).ForestcoverchangestatisticsderivedfromNDVIclassificationshowedthatdenseforestdeclinedfrom525ha(67%)to421ha(54%)whilemediumdenseforestincreasedfrom253ha(32%)to356ha(45%).BothsupervisedandNDVIclassificationapproachesshowedsimilartrendsofforestchange,i.e.decreaseofdenseforestandincreaseofmediumdenseforest,whichindicatesdenseforesthasbeenconvertedtomediumdenseforest.Areaofbarelandwasunchanged.Illicitfelling,encroachment,andsettlementnearforestscausedthedenseforestdeclinewhileshortandlongrotationplantationsraisedinvariousyearscausedtheincreaseinareaofmediumdenseforest.ProtectivemeasuresshouldbeundertakentocheckfurtherdegradationofforestatKNP.

  • 标签: 遥感和地理信息系统 森林覆盖率 LANDSAT TM遥感影像 国家公园 覆被变化
  • 简介:Byusingthedatasetoflightraindaysandlowcloudcoverat51stationsinSouthChina(SC),andthemethodoflinearregressionandcorrelativeanalysis,weanalyzethespatiotemporalcharacteristicsofthelightraindaysandlowcloudcoverincludingannualvariationandlong-termseasonalchange.Theresultsareasfollows:(1)ThetrendsoflightraindaysandlowcloudcoveroverSCareopposite(lightraindaystendedtodecreaseandlowcloudcovertendedtoincreaseinthepast46years).Thevaluedistributedineastishigherthanthatinwest,andcoastalareahigherthaninlandarea.(2)Theregressioncoefficientsoflightraindaysandlowcloudcoverduring1960-2005are4.88d/10yearsand1.14%/10yearsrespectively,whichhadallpassedthe0.001significancelevel.(3)Variationsoflightraindaysarerelativelysmallinspringandsummer,buttheircontributionsarelargerforannualvaluethanthatofautumnandwinter.(4)Therearetworegionswithlargevaluesofaerosolopticaldepth(AOD),whichdistributeincentralandsouthernGuangxiandPearlRiverDelta(PRD)ofGuangdong,andthevalueofAODinPRDisupto0.7.Theaerosolindexdistributedincoastalareaishigherthanintheinlandarea,whichissimilartothelightraindaysandlowcloudcoveroverSC.AerosolindexesinSCkeptincreasingwithfluctuationduringthepast27years.TheGDPofthethreeprovincesinSCincreasedobviouslyduringthepast28years,especiallyinGuangdong,whichexhibitedthatthereissimultaneouscorrelationbetweenlightraindayswiththevariablesoflowcloudcoverandreleaseofaerosolsoverSCduring1960to2005.

  • 标签: