简介:Inthisstudy,changesinArcticseaicethicknessforeachiceagecategorywereexaminedbasedonsatelliteobservationsandmodelledresults.InterannualchangesobtainedfromIce,Cloud,andLandElevationSatellite(ICESat)-basedresultsshowathicknessreductionoverperennialseaice(icethatsurvivesatleastonemeltseasonwithanageofnolessthan2year)uptoapproximately0.5–1.0mand0.6–0.8m(dependingoniceage)duringtheinvestigatedwinterandautumnICESatperiods,respectively.Pan-ArcticIceOceanModelingandAssimilationSystem(PIOMAS)-basedresultsprovideaviewofacontinuedthicknessreductionoverthepastfourdecades.Comparedto1980s,thereisaclearthicknessdropofroughly0.50min2010sforperennialice.Thisoveralldecreaseinseaicethicknesscanbeinpartattributedtotheamplifiedwarmingclimateinnorthlatitudes.Besides,wefigureoutthatstronglyanomaloussoutherlysummersurfacewindsmayplayanimportantroleinpromptingthethicknessdeclineinperennialicezonethroughtransportingheatdepositedinopenwater(primarilyviaalbedofeedback)inEurasiansectordeepintoabroaderseaiceregimeincentralArcticOcean.Thisheatsourceisresponsibleforenhancedicebottommelting,leadingtofurtherreductioninicethickness.
简介:ThemainactivitiesinthejointexpeditionbetweenCHINAREandANAREonAmeryiceshelfareintroduced.Five-daycontinuousGPSobservationdatacollectedonthesitewhichlocatesatthefrontalpartofAmeryiceshelfwasprocessedwithprecisepointpositioning(PPP)technologybasedonpreciseproductsfromIGS.VelocityofthesurfaceiceflowonAmerycanbederivedfromthePPPsolution.Preliminaryresultshowsthatthesurfaceiceflowvelocityofthesiteis2.25metersperday,themotiondirectionisnortheastward.SemidiurnaloceanictideanddiurnaloceanictidesignalofthatsitecanberecoveredfromtheheightvariationseriesofPPPsolution.Theseabovesolutionscanbeusedtotheconsequentmassbalancecalculation.
简介:Asthefirstacrobaticartistictroupewiththeperformanceonice,HeilongjiangAcrobaticsandDancingonIceTroupehasbeenonafastdevelopingwayinvirtueofherperseveranceonacrobaticsandhasstartedtoshineuniquelyintheperformancemarketsinceherfounding.
简介:海冰飘移的许多有趣的特征取决于大气拖系数(C)并且海洋拖系数(Cw)。Parameterizations拖系数而非经常的价值提供我们在海冰上看卓见进这些特征的依赖的一个方法调节。在现在的学习,parameterized冰拖系数被包括进免费飘移的海冰动态模型,并且在海冰之间的风因素和偏转角度漂流并且弯屈速度以及C到Cw被学习在象本地人那样的影响因素上调查他们的依赖拖系数,大浮冰和山脉几何学。结果在理想化的稳定的海洋揭示那,C/Cw在边缘的冰地区为小冰大浮冰与增加的冰集中显然增加,当它为大大浮冰在稳定的水平(0.20.25)留在中央冰地区时。风因素起初很快增加并且当A比20%大时,接近0.018的稳定的水平。并且偏转角度从起始的价值很快落下接近80慦桳潩?
简介:Asasubstitutefortheoriginaldisplacedpolegrids,asimplerotatedsphericalcoordinatesystemwasintroducedintotheCommunitySeaIceModelversion4(CSIM4),whichisacomponentoftheCommunityClimateSystemModel(CCSM)oftheAmericanNationalCenterofAtmosphericResearch(NCAR),todealwiththe'poleproblems'.Inthenewcoordinates,boththegeographicalNorthPoleandSouthPolelieinthemodelequatorandgridsizesnearthepolarregionaremoreuniform.WithreanalysisdatasetofAmericanNationalCentersforEnvironmentPrediction(NCEP)andLevitusdatasetwithoutconsideringsub-mixedlayerheatflux,themodelwasintegratedfor100yearswiththermodynamicsprocessinvolvedonlyintheformer49yearsandbothdynamicandthermodynamicprocessesinvolvedinthelefttime.Innerconsistencyofmodelresultswascheckedwithnocontradictionfound.Theresultsoflast10years'modeloutputwereanalyzedanditisshownthatthesimulatedseaiceseasonalvariationisrationalwhereasseaiceextentintheBarentsSeainwinterislargerthanthatofobservation.Numericalexperimentoninfluenceofsub-mixedlayerheatfluxwasalsocarriedoutanditisshownthatthesub-mixedlayerheatfluxcanmodulateseasonalvariationofseaicegreatly.Asamodelcomponent,theseaicemodelwithrotatedsphericalcoordinateswascoupledwithothermodels(theoceanicgeneralcirculationmodelistheLASG/IAPClimateSystemOceanModel(LICOM)withreducedgrid,othermodelsarecomponentsofNCARCCSM2)formingaclimatesystemmodelanditspreliminaryresultswerealsogivenbriefly.
简介:Theseaicecoverdisplaysvariousdynamicalcharacteristicssuchasbreakup,rafting,andridgingunderexternalforces.Tomodeltheicedynamicprocessaccurately,theeffectivenumericalmodelingmethodshouldbeestablished.Inthispaper,amodifiedparticle-in-cell(PIC)methodforseaicedynamicsisdevelopedcouplingthefinitedifference(FD)methodandsmoothedparticlehydrodynamics(SPH).Inthismethod,theicecoverisfirstdiscretizedintoaseriesofLagrangianiceparticleswhichhavetheirownsizes,thicknesses,concentrationsandvelocities.TheicethicknessandconcentrationatEuleriangridpositionsareobtainedbyinterpolationwiththeGaussianfunctionfromtheirsurroundingiceparticles.ThemomentumoficecoverissolvedwithFDapproachtoobtaintheEuleriancellvelocity,whichisusedtoestimatetheiceparticlevelocitywiththeGaussianfunctionalso.Thethicknessandconcentrationoficeparticlesareadjustedwithparticlemassdensityandsmoothlength,whichareadjustedwiththeredistributionoficeparticles.WiththeabovemodifiedPICmethod,numericalsimulationsforicemotioninanidealizedrectangularbasinandtheicedynamicsintheBohaiSeaarecarriedout.ThesesimulationsshowthatthismodifiedPICmethodisapplicabletoseaicedynamicssimulation.
简介:Rivericeisanimportanthydraulicelementintemperateandpolarenvironmentsandwouldaffecthydrodynamicconditionsofriversthroughchangesbothintheboundaryconditionsandthethermalregime.Theriverbendhasbeenreportedasthecommonlocationfortheinitiationoficejamsbecausethewaterflowalongariverbendismarkedlyaffectedbythechannelcurvature.Inthisarticle,theexperimentalstudiesabouttheiceaccumulationinariverbendarereviewed.Basedonexperimentsconductedsofar,thecriteriafortheformationoficejamsintheriverbend,themechanismsoftheiceaccumulationintheriverbendandthethicknessprofileoftheiceaccumulationintheriverbendarediscussed.Thetwo-equationturbulencemodelisusedtosimulatetheiceaccumulationunderanicecoveralongariverbend.Aformulaisproposedfordescribingthedeformationoftheicejambottom.Ourresultsindicatethatallsimulatedthicknessoftheiceaccumulationagreesreasonablywellwiththemeasuredthicknessoftheiceaccumulationinthelaboratory.