学科分类
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17 个结果
  • 简介:Basedonthedataoftemperatureandsalinityofthe137°Esectioninthewintersandsummersfrom1967to1995,thegeo-strophiccurrentofthesectioniscalculatedandanalyzed,andthedriftingtracksofthesatellitetrackingdriftbuoydistributedonthe144°Esectionarealsoanalyzed.InlightofthesurfacedynamicheightdistributionintheCSKatlas,thispapercomparessomefeaturesoftheSubtropicalCountercurrent,theNorthEquatorialCurrentandtheNorthEquatorialCountercurrent.Themainresultsareasfollows:1.TheSubtropicalCountercurrent,theNorthEquatorialCurrentandtheNorthEquatorialCountercurrentarenotsimplesinglecurrents,buthavetwobranchesormore.Oneofthecommonfeaturesofthethreecurrentsmentionedaboveis"multi-branching"ofthecurrent.2.Thezonaldistributionoftheflowvelocitystructure,thealternateandintermittentoccurrenceoftheeastwardandwestwardflows,withashallowerflowlayerandbelongingtothesurfacefloworsubsurfacef

  • 标签: the SUBTROPICAL Countercurrent the NORTH EQUATORIAL
  • 简介:ThecircumfluencearoundtheJiuduanSandbankisthoroughlystudiedbymeansoftheprinci-pleofleastresistanceinfluiddynamics.ThediversionratiooftheNorthChannelfor1998iscalculated,whichisalmostthesameasthefieldsurveydata.ThenormalandminimumdiversionratiosoftheNorthChannelafterstagesⅠ,ⅡandⅢregulationworksaswellasthefuturephaseareobtained.Thenumeri-calresultsandpredictedvalueareaccurate.

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  • 简介:Recentandpaleo-submarinelandslidesarewidelydistributedwithinstrataindeep-waterareasalongcontinentalslopes,uplifts,andcarbonateplatformsonthenorthcontinentalmarginoftheSouthChinaSea(SCS).Inthispaper,high-resolution3Dseismicdataandmultibeamdatabasedonseismicsedimentologyandgeomorphologyareemployedtoassistinidentifyingsubmarinelandslides.Inaddition,depositionmodelsareproposedthatarebasedonspecificgeologicalstructuresandfeatures,andwhichillustratethelocalstressfieldoverentiresubmarinelandslidesindeep-waterareasoftheSCS.TheSCSisoneofthelargestfluvialsedimentsinksinenclosedorsemi-enclosedmarginalseasworldwide.Itthereforeprovidesasetofpreconditionsfortheformationofsubmarinelandslides,includingrapidsedimentaccumulation,formationofgashydrates,andfluidoverpressure.Anewconceptinvolvingtemporalandspatialanalysesistestedtoconstructarelationshipbetweensubmarinelandslidesanddifferenttimescaletriggermechanisms,andthreemechanismsarediscussedinthecontextofspatialscaleandtemporalfrequency:evolutionofslopegradientandoverpressure,globalenvironmentalchanges,andtectonicevents.Submarinelandslidesthataretriggeredbytectoniceventsarethelargestbutoccurlessfrequently,whilesubmarinelandslidestriggeredbythecombinationofslopegradientandoverpressureevolutionarethesmallestbutmostfrequentlyoccurringevents.Insummary,analysisshowsthattheformationofsubmarinelandslidesisacomplexprocessinvolvingtheoperationofdifferentfactorsonvarioustimescales.

  • 标签: SOUTH China Sea SUBMARINE LANDSLIDES SEISMIC
  • 简介:Airtemperatureisakeyindexreflectingclimatechange.Airtemperatureextremesareveryimportantbecausetheystronglyinfluencethenaturalenvironmentandsocietalactivities.TheArcticairtemperatureextremesnorthof60°Nareinvestigatedinthewinter.Dailydatafrom238stationsatnorthof60°Nfromtheglobalsummaryofthedayfortheperiod1979–2015areusedtostudythetrendsofcolddays,coldnights,warmdaysandwarmnightsduringthewintertime.Theresultsshowadecreasingtrendofcolddaysandnights(rateof–0.2to–0.3d/a)andanincreasingtrendofwarmdaysandnights(rateof+0.2to+0.3d/a)intheArctic.Themeantemperatureincreases,whichcontributestotheincreasing(decreasing)occurrenceofwarm(cold)daysandnights.Ontheotherhand,thevarianceatmoststationsdecreased,leadingtoareducednumberofcoldevents.ApositiveAO(ArcticOscillation)indexleadstoanincreased(decreased)numberofwarm(cold)daysandnightsovernorthernEuropeandwesternRussiaandanincreased(decreased)numberofcold(warm)daysandnightsovertheBeringStraitandGreenland.ThelowerextentofArcticautumnseaiceleadstoadecreasednumberofcolddaysandnights.TheoccurrencesofabruptchangesaredetectedusingtheMann-KendallmethodforcoldnightsoccurringinCanadain1998andforwarmnightsoccurringinnorthwesternEurasiain1988.ThisabruptchangemainlyresultedfromthemeanwarminginducedbysouthwindsandanincreasedNorthAtlanticseasurfacetemperature.

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  • 简介:TheNorthYellowSeaBasin(NYSB),whichwasdevelopedonthebasementofNorthChina(Huabei)continentalblock,isatypicalcontinentalMesozoic-Cenozoicsedimentarybasinintheseaarea.ItsMesozoicbasinisaresidualbasin,belowwhichthereisprobablyalargerPaleozoicsedimentarybasin.TheNorthYellowSeaBasincomprisesfoursagsandthreeuplifts.Ofthem,theeasternsagisaMesozoic-CenozoicsedimentarysaginNYSBandhasthebiggestsedimentthickness;thecurrentKoreandrillingwellsareconcentratedintheeasternsag.Thissagiscomparativelyrichinoilandgasresourcesandthushasarelativelygoodpetroleumprospectinthesea.ThecentralsaghasalsoaccommodatedthickMesozoic-Cenozoicsediments.ThelatestresearchresultsshowthattherearethreeseriesofhydrocarbonsourcerocksintheNorthYellowSeaBasin,namely,blackshalesofthePaleogene,JurassicandCretaceous.TheprincipalhydrocarbonsourcerocksinNYSBaretheMesozoicblackshale.AccordingtothedrillingdataofKorea,theblackshalesofthePaleogene,JurassicandCretaceoushaveallcomeuptothestandardsofgoodandmaturesourcerocks.TheNYSBownsanintactsystemofoilgeneration,reservoirandcappingrocksthatcanhelphydrocarbontoforminthebasinandthusithasthegreatpotentialofoilandgas.TheverticaldistributionofthehydrocarbonresourcesismainlyconsideredtobeintheCretaceousandthenintheJurassic.

  • 标签: 地震序列 黄海北部盆地 新生代 华北大陆板块 地层比较
  • 简介:在Changjiang河口的北方经过隧道的背淤泥力量的时间、空间的变化是调查u-sing实验直角的函数(文件结束)方法,与目的到决定强加的进程和时间规模。自从2000年3月,在隧道的每个挖出的单位的back-siltingquantity上的数据被收集了,主要一次15d。背淤泥力量的文件结束分析揭示二个重要模式,它完全解释58。第一个文件结束模式显示出的33%全面变化,和相应过程和time-scales.The是的一个清楚的年度周期由河流的水和输沙量决定了从在上游。第二个文件结束模式揭示在back-siltingstrength和工程活动之间的一种靠近的关系。因为这些过程极大地在这个学习案例中被互连,为41的另外的文件结束模式财务。67%全部的变化不显示出清楚的过程andtime规模。

  • 标签: 长江入海口 北部水道 回淤长度 淤积 河口湾
  • 简介:Basedonthestatisticsofsurfacedrifterdataof1979–2011andthesimulationofnuclearpollutantparticulatemovementssimulatedusinghighqualityoceanreanalysissurfacecurrentdataset,thetransportpathwaysandimpactstrengthofFukushimanuclearpollutantsintheNorthPacifichavebeenestimated.Theparticulatesareusedtoincreasethesamplingsizeandenhancetherepresentativenessofstatisticalresults.Thetrajectoriesofthedriftersandparticulatesarefirstexaminedtoidentifytypicaldriftingpathways.Theresultsshowthattherearethreetypesoftransportpathsfornuclearpollutantsatthesurface:1)mostpollutantparticlesmoveeastwardandarecarriedbytheKuroshioandKuroshio-extensioncurrentsandreachtheeastsideoftheNorthPacificafterabout3.2–3.9years;2)someparticlestravelwiththesubtropicalcirculationbranchandreachtheeastcoastofChinaafterabout1.6yearsaccordingtoonedriftertrajectoryandabout3.6yearsaccordingtoparticulatetrajectories;3)alittleofthemtravelwithlocal,smallscalecirculationsandreachtheeastcoastofChinaafterabout1.3–1.8years.Basedontheparticulates,theimpactstrengthofnuclearpollutantsatthesetimescalescanbeestimatedaccordingtothetemporalvariationsofrelativeconcentrationcombinedwiththeradioactivedecayrate.Forexample,Cesium-137,carriedbythestrongNorthPacificcurrent,mainlyaccumulatesintheeasternNorthPacificanditsimpactstrengthis4%oftheinitiallevelattheoriginatingFukushimaareaafter4years.Duetolocaleddies,Cesium-137inthewesternNorthPacificis1%oftheinitialpollutantlevelafter1.5yearsandcontinuouslyincreasesto3%after4years.Theverticalmovementofradioactivepollutantsisnottakenintoaccountinthepresentstudy,andtheestimationaccuracywouldbeimprovedbyconsideringthree-dimensionalflows.

  • 标签: 北太平洋 核污染物 冲击强度 水陆运输 颗粒污染物 放射性污染物
  • 简介:Thispaperanalyzesthecharacteristicsofsupertyphoons(STYs)overthewesternNorthPacific(WNP)from1965to2005anddescribestheseasonalvariabilityofSTYactivity.TherelationbetweenSTYactivityandtheElNio-SouthernOscillation(ENSO)aswellasthepossiblereasonfortheinfluenceoftheENSOonSTYactivityarealsoinvestigated.Theresultsshowedthataboutonefifthofthetropicalcyclones(TCs)overtheWNPcouldreachtherankofSTY.MostSTYsappearedfromJulytoNovem-berwhiletherewasahighestratiobetweennumberofSTYsandtotalnumberofTCsinNovember.MostSTYsappearedeastofthePhilippineSea.InElNioyears,affectedbyseasurfacetemperature(SST),monsoontroughandweakverticalwindshear,TCfor-mationlocationsshiftedeastwardandthereweremoreSTYsthaninLaNiayearswhentheaffectingfactorschanged.

  • 标签: ENSO 台风活动 西太平洋 西北太平洋 超强 热带气旋
  • 简介:Basedonnewmultibeambathymetricdataandabout300kmlongsingleseismicprofiles,threetopographicunitswereidentified:thecanyons,fracturalvalleyandsubmarineterraceonthenorthofChiweiIslandwhereisastructuraltransitionzonebetweenthesoutherntroughandthemiddletrough.TheChiweiCanyonandtheNorthChiweiCanyonaretwoofthelargestcanyonsintheEastChinaSea(ECS)slope.Topographicfeaturesandarchitecturesofthemaredescribed.Thestudyshowsthatbothofthemareoriginatedalongfaults.TheevolutionandspatialdistributionoftopographicunitsinthestudyareaarecontrolledmainlybythreegroupsoffaultswhichwereformedandreactiveintherecentextensionalphaseofOkinawaTrough.TheChiweiCanyonwasinitiatedduringthemiddlePleistoceneandguidedbyF4thatisaN-StrendingfaultontheslopeandF1,alargeNW-SEtrendingfaultonthetrough.ThepathwaymigrationfromtheremnantchanneltothepresentoneofChiweiCanyonistheresultofupliftoftiltedfaultblockthatiscoupledtotherecentextensionmovementsofthesoutherntrough.ThesubmarineterraceisdetachedfromtheECSslopebytheNEE-trendingfault.TheNorthChiweiCanyon,developingduringthelatePleistocene,isguidedbyF5,aN-Strendingfault,divertedandblockedbythesubmarineterrace.

  • 标签: 海底峡谷 地形特征 断层 扩张运动 冲绳岛
  • 简介:Almosthalfoftheoceanicwatercolumnsexhibitdouble-diffusion.Theimportanceofdouble-diffusioninglobaloceans'saltandheatfluxes,water-massformationandmixing,andcirculationisincreasinglyrecognized.However,suchanimportantphysicalprocessintheoceanhasnotbeenwellstudied.Oneofthereasonsisthedifficultyofparameterizingandquantifyingtheprocesses.Thepaperpresentedhereattemptstoquantifythedouble-diffusivefluxesofsaltandheatintheocean.Previousqualitativeanalysisbyapplyingthewater-massTurnerangle,mTu,totheNorthPacificIntermediateWater(NPIW)layershowedafavorableconditionforsalt-fingeringintheupperNPIWduetotheoverlyingwarm/saltywaterabovethecold/freshNPIWcore,andadoubly-stableconditioninthelowerNPIWwherepotentialtemperaturedecreaseswithdepthwhilesalinityincreases,inducingdoublestratificationwithrespecttobothpotentialtemperatureandsalinity.Thepresentstudygivesaquantitativeestimateofdouble-diffusivefluxesofsaltandheatcontributedbysalt-fingeringintheupperNPIWlayer.

  • 标签: 北太平洋 介质水流 双扩散 盐分 热量 NPIW
  • 简介:AnalysisofArgofloattrajectoriesat1000mandtemperatureat950mintheNorthAtlanticbetweenNovember2003andJanuary2005demonstratestheexistenceoftwodifferentcirculationmodeswithfasttransitionbetweenthem.Eachmodehasapairofcyclonic-anticyclonicgyres.Thedifferenceisthelocationofthecyclonicgyre.Thecyclonicgyrestretchesfromsoutheasttonorthwestinthefirstmodeandfromthesouthwesttothenortheastinthesecondmode.TheobservedmodesstronglyaffecttheheatandsalttransportintheNorthAtlantic.Inparticular,thesecondmodeslowsdownthewestwardtransportofthewarmandsalinewaterfromtheMediterraneanSea.

  • 标签: 大西洋 中尺度环流 生物特征 光谱分析
  • 简介:Mid-latitudeair-seainteractionisanimportanttopicthatattractsaconsiderableamountofresearchinterest.TheKuroshioExtension(KE)isoneofthemainwesternboundarycurrentsandplaysacriticalroleinthemid-latitudeatmosphericcirculation.ThispaperusestheNCEP/NCARreanalysisandHadleyseasurfacetemperaturedatasetstoinvestigatetheinfluenceofoceanicfrontsintheKEregiononsurfaceairtemperatureinNorthAmericaovertheperiod1949–2014.AsignificantcorrelationwasfoundbetweentheKEfrontintensityandthetemperaturesoverNorthAmericainautumnandwinter.Astrong(weak)KEfrontanomalyinautumnisassociatedwithanincreasing(decreasing)surfacetemperatureoverwesternNorthAmericabutadecreasing(increasing)surfacetemperatureovereasternNorthAmerica.Inwinter,centralNorthAmericawarms(cools)whentheKEfrontisstrong(weak).Theresponseoftheatmosphericcirculation,includingwindinthehighandlowtroposphere,troughs,andridges,tothestrengthening(weakening)oftheKEfrontisthemaincauseofthesechangesinsurfacetemperature.

  • 标签: KUROSHIO EXTENSION surface air temperature NORTH
  • 简介:AimtolinkingthevariabilityofdroughtinnorthwestChinatotheoceanicinfluenceofNorthAtlanticSSTsatthebackgroundofglobalwarmingandattheregionalclimatechangeshiftingstages,yeararidityindexvariationsinnorthwestChinaandsummerNorthAtlanticseasurfacetemperature(SST)variationsareexaminedforthe44aperiodof1961-2004usingsingularvaluedecomposition(SVD)analysis.ResultsshowthattheSSTanomalies(SSTA)intheNorthAtlanticinsummerreflectedthreebasicmodels.ThefirstSVDmodeofSSTpatternshowsadipole-likevariationwiththepositivecenterlocatedatsouthwestandnegativecenteratnortheastofextratropicalNorthAtlantic.AnditstronglyrelatestothepositivetrendinAIvariationinnorthwestChina.ThesecondcoupledmodesdisplaythecoherentpositiveanomaliesinextratropicalNorthAtlanticSSTandthemarkedoppositetrendofAIvariabilitybetweennorthandsouthofXinjiang.Inaddition,thelagcorrelationanalysisofthefirstmodeofSSTAandgeopotentialheightsat500hPavariationsalsoshowsthattheindicationoftheformerinfluencingthelatterconfiguration,whichresultinhigherairtemperatureandlessprecipitationwhentheSSTAintheNorthAtlanticOceaninsummermotivatedEurasiancirculationofEApattern,furthertoinfluencethewet-dryvariationsinnorthwestChinabytheocean-to-atmosphereforcing.

  • 标签: 干燥度 SSTA 远程并置对比 SVD 中国
  • 简介:Throughdensifiedsurfacesamplingofforaminiferaandaccurateelevationmeasurementalongthreetransectlinesinopen-coasttidalsalt-marshofJianchuan,particularsalt-marshforaminiferaassemblageswerefound.Thesalt-marshforaminiferaassemblagesaredistributedinwell-definedverticalzonationswithrespecttoelevationandcloselyparallelmarshfloralzonations.Atthetopoftheverticalzonationallforaminiferadisappearabruptlywhichareaccuratelylocatedatthehighesthighwaterdatum.Thisdistributionpatterncanbeusedtorelocateformersealevelsaccurately(toanaccuracyofwithin±5cm).Amodemregionalcriterionofforaminiferaforrelocatingtheformersealevelsinhighresolutioninourcountryisprovided,anddeficienciesofstudyingtheverticalzonationonlyinshelteredcoastsalt-marshabroadarefilledup.

  • 标签: Jianchuan of North Jiangsu Province open-coast
  • 简介:Basinmodelinghasbecomeanimportanttoolforanalyzingsedimentarybasins.TheNorthSubbasinoftheSouthYellowSeaBasinisfilledwiththickMeso-Cenozoicterrigenousdepositsduringtheriftevolutionstage.Theaccumulationofdataandachievementsofgeologicalinvestigationsinrecentyearshaveprovidedthepreconditionsforbasinmodeling.Thenecessaryparametersandgeologicalelementsforsimulationsarecollatedandsummarized.Modelingoftectono-thermalevolutionisperformedandtherelatedtrendinheatflowisreconstructedandcalibrated.Theheatflowvaluecommencesfromanaveragelevelof61mW/m~2duringMiddleLateJurassic,risestoabout80mW/m~2fromcirca145Matocirca74Ma,andthenundergoesagradualdeclineto65mW/m~2untiltheendofOligocene.Threeevolutionaryphases,namely,theinitialriftingphase,syn-riftingphase,andpost-riftingphase,havebeenidentified.ThemodelingresultsshowthattheNorthSubbasingenerallyentersintoastageofstrongriftingduringCretaceousandundergoesrapidsubsidenceuntiltheLateCretaceous,thenfollowsbyastageofmoderateriftingduringthePaleogene.Theinputandgeneralworkflowinvolvedin3-Dmodelingareintroduced.ReconstructionofthepetroleumsystemintheNorthSubbasinrevealsthatthethresholddepthofhydrocarbongenerationislocatednearthetopofthePaleogeneFuningformation,andtheunderlyingJurassicandCretaceoussourcerockshavereachedorexceededpeakoilgenerationandhavealmostcompletedthegenerationandexpulsionofhydrocarbons.ThemaingenerationandexpulsionintheJurassicsourcerockstakeplaceduringthesyn-riftingandpost-riftingphases,whereasthepeakgenerationandexpulsionintheCretaceousandPaleogenesourcerockstakeplaceduringthepost-riftingphase.Althoughthestudyareaisstillarelativelylessexploredsedimentarybasin,theresultsofmodelingcanprovidevaluableinformationforexploration.Apreliminarydiscussionofthemainuncertaintyfactor

  • 标签: 南黄海盆地 三维建模 凹陷 盆地模拟 流域 沉积盆地
  • 简介:WhiletheAntarcticSlopeCurrent(ASC)hasbeenintensivelystudiedfortheEastAntarcticaslopeareaandtheWeddellSea,itsfateinthewesternAntarcticPeninsula(WAP)regionremainsmuchlessknown.DatafromtwocruisesconductedneartheSouthShetlandIslands(SSIs)andtheElephantIsland(EI),oneinaustralsummerof2004andoneinaustralwinterof2006,wereanalyzedtoprovideabroadpictureofthecirculationpatternoverthecontinentalslopeofthesurveyedarea,andaninsightintothedynamicalbalanceofthecirculation.Theresultsindicatethatsouthwestwardcurrentsarepresentovertheupperslopeinthestudyarea,indicatingtheASCintheWAPregion.NeartheShackletonGap(SG)northoftheEI,thesouthwestwardslopecurrentsneartheshelfbreakarecharacterizedbyawatermasscolderandfresherthantheambientwater,whichproducescross-slopedensitygradientsandthenverticalshearofthealong-slope(oralong-isobath)velocity.Theverticalshearisassociatedwithareversalofthealong-slopecurrentfromnortheastwardatsurfacetosouthwestwardindeeperlayers,oradepth-intensificationofthesouthwestwardslopecurrents.ThewatermasswithtemperatureandsalinitycharacteristicssimilartotheobservedcoldandfreshwaterisalsorevealedonthesouthernslopeoftheScotiaSea,suggestingthatthiscoldandfreshwaterisoriginatedfromtheScotiaSeaslopeandflowssouthwestwardthroughtheSG.OvertheshelfnorthoftheSSIs,thecoldandfreshwatermassisalsoobservedandoriginatesmainlyfromtheBransfieldStrait.Inthisarea,verticalstructureofthesouthwestwardslopecurrentsisassociatedwiththeonshoreintrusionoftheupperCircumpolarDeepWaterthatcreatescross-slopedensitygradients.

  • 标签: Antarctic SLOPE Current dynamical balance water
  • 简介:Calibrationsbetweensodium(Na+)concentrationsfromaMt.Loganicecoreandsealevelpressure(SLP)seriesshowthatNa+concentrationsarecloselycorrelatedwiththeautumn-time(SeptemberOctober-November)Aleutianlow(AleuLow).AdeepeningoftheAleuLowstrengthensthetransportofsea-saltaerosolsfromtheNorthPacifictotheMt.Loganregion.TheMt.LoganNa+recordisusedtodevelopa292a(1688~1979)reconstructionoftheAleuLowrevealingadramaticintensificationofatmosphericcirculationovertheNorthPacificregionsincethe20thcentury.MeanSLPoftheAleuLowwasabout1hPalowerduringthe20thcenturythanduringpriorperiods.ThestrongestdeepeningoftheAleuLowappearedinthe1950s.SignificantcorrelationsarealsofoundbetweentheMt.LoganAleuLowproxyseriesandthePacificdecadaloscillation(PDO)andPacificcirculation(PC)indexduringthe20thcentury.Evolutionaryspectralanalysisoftheproxyrecordshowssignificantperiodicitiesfrom15to30aconsistentwithPDOfluctuationsandthebidecadaloscillationofNorthPacificatmosphere-oceancirculation.Aperiodof11aintheAleuLowrecordmaybeassociatedwiththeSchwabe11-acycleofsunspotactivity.AdditionallongericecorerecordsfromthisregionwillaidintheeffortstofurtherunderstandtheclimaticchangeovertheNorthPacificregion.

  • 标签: 太平洋 大气循环 海洋气象 海冰