简介:ChemicalfluxesofAsianriversintooceansbeardifferentregionalvariations.Threezonesarecharacteristicofdistinctdissolvedsedimentloadsandyieldsandionicconcentration.RiversintooceansinChinaplayanimportantroleinAsiabecauseoftheirdifferentchemicalfluxes,amongwhichthosedrainingtheLoessPlateauhavehighionicconcentration,lowwaterdischargesanddissolvedsedimentloadsandyields.Climate,vegetation,soilandstratalithology,chemicalweatheringintensityandtectonicactivitydominatechemicalfluxesofAsianriversintooceans,anddifferentfactorshavedifferenteffectsonthechemicalfluxesofseparateregionalrivers.RisingoftheTibetPlateaualsoexertsanimportantinfluenceonchemicalcompositionsofriversoriginatingfromit.
简介:StudyofthemajorAsianriversdischargetotheoceanrevealsvariationsoftheirwaterdischargesandsedimentloads,andlocalcharacteristicsofriversedimentconcentrations.Onthebasisofthis,theAsianriversfallintothreeregions,includingEurasiaArctic,EastAsia,SoutheastandSouthAsiaRegions.TheEurasiaArcticRegionischaracterizedbythelowestsedimentconcentrationandload,whiletheEastAsiaRegionisofthehighestsedimentconcentrationandhighersedimentload,andtheSouth-EastandSouthAsiaRegionyieldshighersedimentconcentrationandhighestsedimentload.Thesedimentloadsoftheseregionsaremainlycontrolledbyclimate,geomorphologyandtectonicactivity.TheEurasiaArcticriverswithlargebasinareasandwaterdischarge,drainlowreliefwhichconsistsoftundrasediment,thuscausingthelowestsedimentload.TheEastAsiariverswithsmallbasinareasandlowestwaterdischarges,drainextensiveloessplateau,andtransportmosterodibleloessmaterial,whichresultsinhighestsedimentconcentration.TheSEandSouthAsiariversoriginatingfromtheTibetPlateauhavelargebasinareasandthelargestwaterdischargesbecauseoftheSummerMonsoonandhighrainfallinfluence,causingthehighestsedimentload.InAsia,tectonicmotionoftheTibetPlateauplaysanimportantrole.ThoselargeriversoriginatingfromtheTibetPlateautransportabout50%oftheworldriversedimentloadtooceanannually,forminglargeestuariesanddeltas,andconsequentlyexertingagreatinfluenceonsedimentationinthecoastalzoneandshelves.
简介:Theoperationalclimateforecastsystem(CFS)oftheUSNationalCentersforEnvironmentalPredictionprovidesclimatepredictionsovertheworld,andCFSproductsarebecominganimportantsourceofinformationforregionalclimatepredictionsinmanyAsiancountrieswheremonsoonclimatedominates.Recentstudieshaveshownthat,onmonthly-to-seasonaltime-scales,theCFSishighlyskillfulinsimulatingandpredictingthevariabilityoftheAsianmonsoon.Thehigher-frequencyvariabilityoftheAsiansummermonsoonintheCFSisanalyzed,usingoutputfromaversionwithaspectraltriangulartruncationof126wavesinhorizontaland64sigmalayersinvertical,focusingonsynoptic,quasi-biweekly,andintraseasonaltime-scales.TheonsetprocessesofdifferentregionalmonsooncomponentswereinvestigatedwithinAsia.AlthoughtheCFSgenerallyoverestimatesvariabilityofmonsoononthesetime-scales,itsuccessfullycapturesmanymajorfeaturesofthevariancepatterns,especiallyforthesynoptictime-scale.TheCFSalsocapturesthetimingofsummermonsoononsetsoverIndiaandtheIndo-ChinaPeninsula.However,itencountersdifficultiesinsimulatingtheonsetoftheSouthChinaSeamonsoon.ThesuccessandfailureoftheCFSinsimulatingtheonsetofmonsoonprecipitationcanalsobeseenfromtheassociatedfeaturesofsimulatedatmosphericcirculationprocesses.Overall,theCFSiscapableofsimulatingthesynoptic-to-intraseasonalvariabilityoftheAsiansummermonsoonwithskills.Asforseasonal-to-interannualtime-scalesshownpreviously,themodelisexpectedtopossessapotentialforskillfulpredictionsofthehigh-frequencyvariabilityoftheAsianmonsoon.
简介:Inthispaper,wecalculatedmulti-scaleresidualgeoidanomalieswiththemethodofgeoidseparationprocessing,accordingtoEGM2008ultra-highordergravityfieldmodel,remove-restoretechniqueandStokesintegral.TheEastAsiancontinentalmarginwasselectedasthestudyarea.Theresidualgeoidanomalieshavebeencalculatedbyprogramming.Onthebasisofresidualgeoidanomaliesatvariousorders,theinterlayergeoidanomaliesatdifferentdepthswerecalculatedtodepictthespatialdistributioncharacteristicsoftheresidualgeoid.Finally,weconductedadetailedgeophysicalinterpretationforthestudyareaaccordingtothegeoidanomaliesincombinationwithothergeophysicaldatasets.Fourconclusionscanbeoutlinedasfollows:1)itisimpracticablethatgeoidanomaliesareusedintheinterpretationoftheshallowobjectsduetotheinfluenceoftheterrain;2)theanomaliesofresidualgeoidcanreflecttheintensityofsmall-scalemantleconvectionintheasthenosphere;3)theinterlayergeoidanomaliescanreflectthemagmaticactivitiesassociatedwiththemantleconvectionandmantleplumeindifferentscales;4)thestudyofthegeoidmayprovideanapproachfortheresearchofthesubductionzone,mantleconvectionandmantleplume.
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简介:TheEastAsianmonsoonsysteminfluencesthesedimentationandtransportoforganicmatterinEastAsianmarginalseasthatisderivedfrombothterrestrialandmarinesources.Inthisstudy,wedeterminedorganiccarbon(OC)isotopevalues,concentrationsofmarinebiomarkers,andlevelsofOCandtotalnitrogen(TN)incoreYSC-1fromthecentralSouthYellowSea(SYS).OurobjectivesweretotracethesourcesofOCandvariationsinpalaeoproductivitysincethemiddleHolocene,andtheirrelationshipswiththeEastAsianmonsoonsystem.Therelativecontributionsofterrestrialversusmarineorganicmatterincoresedimentswereestimatedusingatwo-end-membermixingmodelofOCisotopes.ResultsshowthatmarineorganicmatterhasbeenthemainsedimentconstituentsincethemiddleHolocene.Thevariationofterrestrialorganiccarbonconcentration(OCter)issimilartotheEASMhistory.However,thevariationofmarineorganiccarbonconcentration(OCmar)isoppositetothatoftheEASMcurve,suggestingOCmarisdistinctlyinfluencedbyterrestrialmaterialinput.InputsofterrestrialnutrientsintotheSYSoccurintheformoffluvialandaeoliandust,whileconcentrationsofnutrientsinsurfacewaterarederivedmainlyfrombottomwaterviatheYellowSeacirculationsystem,whichiscontrolledbytheEastAsianwintermonsoon(EAWM).Variationsinpalaeoproductivityrepresentedbymarineorganicmatterandbiomarkerrecordsare,ingeneral,consistentwiththerecentEAWMintensitystudies,thus,comparedwithEASM,EAWMmayplaythemainroletocontrolthemarineproductivityvariationsintheSYS.
简介:AWRF-Chemmodelincludingacomprehensivegas-phasenitrogenchemistrymodulewasusedtosimulateaseveredusteventappearingintheeasternChinaon19-25March,2002.ThemodelingresultwellreproducedPM10concentrationsinvariousdistancesfromthedustsourcesandthetransportpathwayoftheduststrom.TheresultsshowedthatboththeconcentrationsandthedrydepositionfluxesofPM10increasedovertheChinaseasduringthedusteventfollowingthepassageofacoldfrontsystem.ThemaximumfluxesofPM10intheYellowSeaandtheEastChinaSeaduringthedusteventwere5.5and8.4timesofthosebeforetheevent,respectively.However,thetemporalvariationsofthedrydepositionfluxesofparticulateinorganicnitrogendifferedovertheYellowSeafromthoseovertheEastChinaSea.NitrateandammoniuminthewholenorthernChinarapidlydecreasedbecauseoftheintrusionofdust-loadedairon19March.ThedustplumearrivedintheYellowSeaon20March,decreasingtheparticulateinorganicnitrogeninmassconcentrationaccordingly.TheminimumdrydepositionfluxesofnitrateandammoniumintheYellowSeawereabout3/5and1/6ofthosebeforethedustarrival,respectively.Incontrast,whenthedustplumecrossedovertheYangtzeDeltaarea,itbecameabundantinnitrateandammoniumandincreasedtheconcentrationsanddrydepositionfluxesofparticulateinorganicnitrogenovertheEastChinaSea,wherethemaximumdrydepositionfluxesofnitrateandammoniumincreasedapproximatelyby4.1and2.6timesofthosepriortothedustarrival.