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.
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
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.
简介:Basedonthedataoftemperatureandsalinityofthe137°Esectioninthewintersandsummersfrom1967to1995,thegeo-strophiccurrentofthesectioniscalculatedandanalyzed,andthedriftingtracksofthesatellitetrackingdriftbuoydistributedonthe144°Esectionarealsoanalyzed.InlightofthesurfacedynamicheightdistributionintheCSKatlas,thispapercomparessomefeaturesoftheSubtropicalCountercurrent,theNorthEquatorialCurrentandtheNorthEquatorialCountercurrent.Themainresultsareasfollows:1.TheSubtropicalCountercurrent,theNorthEquatorialCurrentandtheNorthEquatorialCountercurrentarenotsimplesinglecurrents,buthavetwobranchesormore.Oneofthecommonfeaturesofthethreecurrentsmentionedaboveis"multi-branching"ofthecurrent.2.Thezonaldistributionoftheflowvelocitystructure,thealternateandintermittentoccurrenceoftheeastwardandwestwardflows,withashallowerflowlayerandbelongingtothesurfacefloworsubsurfacef
简介:ThecircumfluencearoundtheJiuduanSandbankisthoroughlystudiedbymeansoftheprinci-pleofleastresistanceinfluiddynamics.ThediversionratiooftheNorthChannelfor1998iscalculated,whichisalmostthesameasthefieldsurveydata.ThenormalandminimumdiversionratiosoftheNorthChannelafterstagesⅠ,ⅡandⅢregulationworksaswellasthefuturephaseareobtained.Thenumeri-calresultsandpredictedvalueareaccurate.
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.
简介:在华南海(SCS)的海条件的统计描述被分析调查一30年(1976-2005)每天数字地模仿了波浪高度和风速度数据。月刊这些参数的变化显示出那波浪高度和风速度有最小在12月分别地在5月和2.04m和8.12ms1,的山峰价值分别地0.54m和4.15ms1,珍视。高度和风速度和年度、季节、每月的吝啬的海的随后的描述基于这些说的每日的波浪的统计分析参数也是做。结果出现那一般来说,细微的海国家在SCS占优势并且将近在所有季节和月有最高的出现。当时,中等的海条件在12月和1月的冬季月内占优势光滑(小浪)海状态在5月占优势。而且,海状态的空间变化显示出那平静并且平静的海面条件在南部的SCS有高出现(25%-80%)。细微的海条件在SCS的大多数部分上显示出最大的出现(25%-55%)。不平、很不平的海的高出现(8%-17%)在中央SCS在一些区域上散布。到非凡的条件的从高度的海状态显示出稀罕出现(<12%)在北SCS。平静(玻璃质)海状况不在SCS显示出出现。
简介:Basedupontheone-yearwindwavemeasurementdata,collectedfromtheSouthChinaSea(SCS)atcoordinates20°36.298?N,110°45.433?E.byAcousticWaveAndCurrent(AWAC),weanalyzedthewavecharacteristicsandconcludedthatthemostcommonwavedirectionwasEandthesecondmostcommondirectionwasENE,themeanandthemaximumvaluesofsignificantheightwas1.2mand4.36m,respectively.Themeanperiodwas4.0s.Wealsoevaluatedthewavespectrumsunderconditionsexistinginthreetyphoons:Rumbi,JetiandUtor.Wefoundthatunimodalspectrumsoccurredmoreoftenthanothers,andthemaximumspectrumpeakwas30.7911m2s.Theminimumpeakfrequencywas0.0625Hz,andthemeanpeakfrequencywas0.126Hz.Thewaveperiodisimportantforthedesignofmarinestructures,especiallythepositionofpeakfrequencyhadagreatinfluenceonthestresscalculation.Spectralanalysisshowedthatthevaluesofpeakfrequencydistributedbetween0.063Hzand0.217Hz,withthemeanvalue0.114Hz.Wefitthenormalizedspectrumwith6theoreticalspectralmodels,outofwhich,theWenspectrum,JONSWAPspectrumandWallopsspectrumwereprovedtogivethebestfit.WhatdistinguishedtheWenSpectrumfromtherestwasthatitdoesnotrelyonthemeasuredspectrumforparameterestimation.Hence,werecommendthattheWenspectrumshouldbewidelyusedinmarineconstruction.
简介:根据一系列重要历史的地图,即,华南海岛,Nansha岛,Zhongsha岛,Xisha岛,Yongxing岛和Shidao岛的地点地图,并且太平天国的岛(在1946由中华民国的内部的部的领土的管理部门转存),并且中华民国的管理区域地图在1948出版了,包围华南海岛的击破的线在华南代表瓷器海边界它是连接与的两个,和延期,中国的陆地边界。在当稳固的线被用来代表陆地boundarya时,击破的线被用来代表水边界的那时间,通用方法在然后国际性地被认出的地图使用了。上述观察在为在华南海区域上的国际海上的定界线是有用的华南海提供瓷器海边界的历史、科学的证据。
简介:Integratedstudiesofverticalsedimentarysequences,grainsizes,andbenthicforaminiferaandostracoda,incombinationwithAMS14Cdating,and210Pband137CsanalysiswerecarriedoutinthreevibracorestakenfromtheareaofrelictdepositsonthewesternSouthYellowSea.Therelictsands,whichareabout0.4mthick,overlieontheEarlyHolocenecoastalmarshortidalflatdepositswithanevidenterosionalinterfaceinbetween.Themiddleandupperpartsorsometimesthewholeoftherelictsandshavebeenreworkedunderthemoderndynamicenvironment.Thesedimentationratevariesbetween0.20–0.30cmyear-1.Therelictsandsshowabimodalgrain-sizedistributionpatterninfrequencycurves,withasharppeakinthecoarsefractionbetween3Φand4Φandasecondarypeakinthefinefractionofabout7Φ.Ofthebenthicforaminiferalandostracodassemblages,thereworkedrelictsandsarecharacterizedbythemixingofthenearshoreeuryhalineshallow-waterspeciesanddeeperwaterspecies.TheerosionalinterfaceatthebottomoftherelictsandsisconsideredasaregionalravinementsurfaceformedduringthetransgressionintheEarlyHoloceneduetoshorefaceretreatinglandwards.Therelictsandswereaccumulatedontheravinementsurfaceduringthetransgressioninthedeglaciationperiodaslagdepositsafterwinnowingandreworkingbymarinedynamicprocesses.Andthesecondarypeakoffinefractioninthefrequencycurvefortherelictsandssuggeststheinputoffine-grainedsedimentsduringthereworkingprocess.Astheconclusion,therelictsandsinthestudyareaareinterpretedasatypeofreworkedrelictsediments.
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.
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。
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.
简介:Thispaperanalyzesthecharacteristicsofsupertyphoons(STYs)overthewesternNorthPacific(WNP)from1965to2005anddescribestheseasonalvariabilityofSTYactivity.TherelationbetweenSTYactivityandtheElNio-SouthernOscillation(ENSO)aswellasthepossiblereasonfortheinfluenceoftheENSOonSTYactivityarealsoinvestigated.Theresultsshowedthataboutonefifthofthetropicalcyclones(TCs)overtheWNPcouldreachtherankofSTY.MostSTYsappearedfromJulytoNovem-berwhiletherewasahighestratiobetweennumberofSTYsandtotalnumberofTCsinNovember.MostSTYsappearedeastofthePhilippineSea.InElNioyears,affectedbyseasurfacetemperature(SST),monsoontroughandweakverticalwindshear,TCfor-mationlocationsshiftedeastwardandthereweremoreSTYsthaninLaNiayearswhentheaffectingfactorschanged.
简介:由于山论的阻塞,弱风醒来在华南海发生在夏天离开东北越南。在风下面醒来,温暖的水从两个高分辨率的卫星数据和水道学的观察被观察。温暖的水的wake在6月形成,继续在7月和8月成熟,开始在9月腐烂,并且消失在10月。温暖的水也弄醒表演柔韧日报它在日子期间加强并且在夜里变弱的变化。温暖的水醒来能通过导致风的混合被产生并且热(潜伏的热流动)过程。在这份报纸,一个混合的层模型被用来分别地在季节、日报的timescales上评估二个过程的相对重要性。结果比导致风的混合在季节的timescale上处理的证明热过程做更大的贡献到wake,当时温暖的水醒来被导致风的混合统治过程在上一日报timescale。
简介:Thediffusionattenuationcoefficientfordownwellingirradiance,Kd(490),isanimportantopticalparameterofseawater.Theopticalproperty,Kd(490),aroundNanshaIslandsintheSouthChinaSeawasanalyzedbasedonopticaldataprofilesmeasuredwithSPMR(SeaWiFSProfilingMultichannelRadiometer)andSMSR(SeaWiFSMuitichannelSurfaceReference)instrumentinAprilandMay,1999.TheresultsshowthatKd(490)iscloselycorrelatedwithchlorophyll-aconcentration,Cchl.a,andthattheverticaldistributionofKd(490)showsthestrongstratificationofthewatercolumninthisarea.Kd(490)hasasimilarverticalco-variationasKL(490),thediffusiveattenuationcoefficientforupwellingradiance.Bothcoefficientsincreasewithdepthintheupperlayer,whereKL(490)isgreaterthanKd(490);andafteradepth,approximativelyatthechlorophyllmaximum,theydecreasewithdepth,withtheformerbeingsmallerthanthelatter.
简介:AnalternativeindexfortheonsetofsummermonsoonovertheSouthChinaSea(SCS)hasbeendesignedbasedonthereanalysisdataoftheNationalCentersforEnvironmentalPrediction-NationalCenterforAtmosphericResearch(NCEP/NCAR).ItisfoundthatthedifferencebetweenthegeopotentialthicknessoverGuangzhouandManilacanbeusedasanalternativeindexfortheonsetofsummermonsoonovertheSCS.SincetheconvectiveheatingaltersthegeopotentialheightandthedistancebetweenGuangzhouandManilaisofsynopticscaleinthegeostraphicframework,theindexcanrepresentthestrengthofheatingandthefirstbarocliniccellovertheSCS.Bycomparisonbetweendifferentindices,itisfoundthatthesummermonsoononsetovertheSCScanbeascertainedbytheverticalzonalwindshearbetween200hPaand850hPa,thezonalwindat850hPa,theOLRanomaly,andthealternativeindexdefinedinthepresentpaper.Themeridionalwindshearbetween200hPaand850hPaalwaysappearsovertheSCSmuchearlierthanthezonalwindshearandcannotbeusedasanindexunderconsideration.
简介:Thecompositionofdetritalmineralswithgradesof0.063-0.25mminthesuperficialsedimentofSouthYellowSeaismainlystudiedinthepaper.Theresearchresultshowsthatthemineralscanbedividedintomorethanfiftysorts.Thelightmineralsaremainlyfeldspar,quartz,mica,etc.Theheavymineralsaremainlycomposedofamphibole,epidote,mica,autogenypyrite,magnetite,hematite,garnet,zirconandsoon,whichmainlydistributeinthesedimentsofsiltyclayandlutaceoussilt.Accordingtothecontentanddistributionofthemainminerals,theresearchareaisdividedintofivemiteralcombinationprovinces.Theassembledtypesofmineralsineveryprovincehavecloserelationshipwithitshydrodynamicconditionsandsedimentaryenvironment.Andthesortsofdetritalmineralsalsoshowthatthedetritalsubstancesinthesedimentaryareasmainlyoriginatefromthedrainageareasofrivers,bedrockweathering,andtransformedsediment,etc.
简介:ThemeasurementsbyusingADCP(500KH)andCTDweremadeduringAugust2000inthesouth(37°55'N,120°25'E)oftheBohaiSea,wherethewaterdepthwasabout16.5m.Thedataofhorizontalvelocitywithsamplingintervalof2minin7layerswereobtained.Thepowerspectrumanalysisofthesedataindicatesthatthereareveryenergeticinfragravitywaveswithaperiodofabout6min.Thecoherencespectrumanalysisandtheanalysisoftemporalvariationofshearshowthattheseinfragravitywavesaremainlythefreewavemodel(propertiesofedgewaves),inthemeantimetheypossesssomecharacteristicsofinternalwaves,whicharelikelyduetothedistinctivemarineenvironmentinthisarea.Itisspeculatedonthattheinstabilityprocesses(chieflyshearinstability)ofshearedstratifiedtidalflowowingtotheeffectofsea-floorslopeinthecoastalareamightbethemainmechanismgeneratingtheseinfragravitywaves.