简介:Inthispaper,anewbiasestimationmethodisproposedandappliedinaregionalensembleKalmanfilter(EnKF)basedontheWeatherResearchandForecasting(WRF)Model.Themethodisbasedonahomogeneouslinearbiasmodel,andthemodelbiasisestimatedusingstatisticsateachassimilationcycle,whichisdifferentfromthestateaugmentationmethodsproposedinpreviousliteratures.Thenewmethodprovidesagoodestimationforthemodelbiasofsomespecificvariables,suchassealevelpressure(SLP).AseriesofnumericalexperimentswithEnKFareperformedtoexaminethenewmethodunderasevereweathercondition.Resultsshowthepositiveeffectofthemethodontheforecastingofcirculationpatternandmeso-scalesystems,andthereductionofanalysiserrors.ThebackgrounderrorcovariancestructuresofsurfacevariablesandtheeffectsofmodelsystembiasonEnKFarealsostudiedundertheerrorcovariancestructuresandanewconcept‘correlationscale’isintroduced.However,thenewmethodneedsfurtherevaluationwithmorecasesofassimilation.
简介:全部的推迟的微粒(TSP)样品沿着Qingdao的海岸在三个地点被收集,中国,在前并且在在2002年3月的主要尘暴期间。为比较,PM_(10)(有空气动力学的直径的微粒物质不到10μm)样品被收集三个地点赎回。词法观察和体积和单个粒子的组合分析被使用扫描与为TSP和PM_(10)的散X光检查系统(SEM/EDX)取样的一个精力装备的电子显微镜学执行。结果证明形态学的不同类型的粒子有类似的形态学的不同元素的作文,而是粒子总是没为非灰尘样品有一样的元素的作文。非灰尘粒子的Themorphology和作文在不同地点是不同的。分数维、球形的粒子为非灰尘样品主要在粗粒级存在,当时在好模式(<10μm)有絮状物,一起结队并且包含外壳的元素的好粒子形成。与非灰尘粒子相比,尘粒以形态学,颗粒大小和作文是更同类的。有andwell分布式的尺寸在灰尘样品统治了的不规则的形状的粒子,包含象Mg那样的外壳的元素,艾尔,Si,Ca,Fe,等等。高硫内容显示了那同类并且多相反应在Qingdao的特定的环境发生在尘粒的表面上。
简介:Settlingvelocityisafundamentalparameterinsedimenttransportdynamics.ForuniformPar-ticles,thereareabundantformulasforcalculationoftheirsettlingvelocities.Butinnaturalfields,sedi-mentconsistsofnon-uniformparticles.Theinteractionamongparticlesiscomplexandshouldnotbeneg-lected.Inthispaper,basedontheanalysisofsettlingmechanismofnon-cohesiveandnon-uniformparti-cles,atheoreticalmodeltodescribesettlingmechanismisproposed.Besidessuspensionconcentrationandupwardturbulentflowcausedbyotherparticles,collisionamongparticlesisanothermainfactorinflu-encingsettlingvelocity.Byintroducingthecollisiontheory,equationsoffallvelocitybeforecollision,colli-sionprobability,andfallvelocityaftercollisionareestablished.Finally,aformulausedtocalculatetheset-tlingvelocityofnon-cohesiveparticleswithwidegraingradationispresented,whichagreeswellwiththeexperimentaldata.
简介:Basedontheanalysisoftropicalcyclone(TC)databaseintheNorthwestPacific(NWP)from1945to2008,wenotonlyextractthetemporalvariationofTCintensityandfrequency,butalsogivetheirspatialdistributionbothintheNWPandintheSouthChinaSea(SCS).TheresultsshowthatthereisanobservationalincreaseofTCactivities,whichmanifestsastheenhancementofthepowerdissipationindex(PDI)andthegrowthofTCfrequency,especiallyfortyphoonsandstrongtyphoons.TheinhomogeneousspatialdistributionsofTCfrequencyandintensityarealsoprovidedbothintheNWPandintheSCS.Forexample,theregionofZhongshaIslandsandDongshaIslandsintheSCS(15°~22°N,115°~120°E),westtothePhilippineIslandsistheplacewithfrequentoccurrenceofstrongtyphoons,amongwhichthewindspeedof7TCsin64yearsexceeds60m/s.
简介:Naturalhazardssuchashurricanesmaycauseextensiveeconomiclossesandsocialdisruptionforcivilstructuresandinfrastructuresincoastalareas,implyingtheimportanceofunderstandingtheconstructionperformancesubjectedtohurricanesandassessingthehurricanedamagesproperly.Theintensityandfrequencyofhurricaneshavebeenreportedtochangewithtimeduetothepotentialimpactofclimatechange.Inthispaper,aprobability-basedmodelofhurricanedamageassessmentforcoastalconstructionsisproposedtakingintoaccountthenon-stationarityinhurricaneintensityandfrequency.Thenon-homogeneousPoissonprocessisemployedtomodelthenon-stationarityinhurricaneoccurrencewhilethenon-stationarityinhurricaneintensityisreflectedbythetime-variantstatisticalparameters(e.g.,meanvalueand/orstandarddeviation),withwhichthemeanvalueandvariationofthecumulativehurricanedamageareevaluatedexplicitly.TheMiami-DadeCounty,Florida,USA,ischosentoillustratethehurricanedamageassessmentmethodproposedinthispaper.Theroleofnon-stationarityinhurricaneintensityandoccurrencerateduetoclimatechangeinhurricanedamageisinvestigatedusingsomerepresentativechangingpatternsofhurricaneparameters.
简介:AerosolsampleswerecollectedonboardtheresearchvesselXuelongduringtheFifteenthChineseAntarcticResearchExpedition(CHINAREXV)inNovember1998-April1999andtheFirstChineseArcticResearchExpeditioninJuly-September1999.TheareastraversedbytheexpeditionarycruisesincludetheArcticOcean,thewesternNorthPacificOceanandtheeasternIndianOcean,covering75°N-69°Sand75°E-133°W.AerosolsampleswerealsotakenattheChineseZhongshanStationinEastAntarcticaduringtheCHINAREXV.Analysisofthesamplesyieldedconcentrationsofnon-sea-saltsulfateandothersolublechemicalspeciesinthemarineboundarylayer.Thedatasuggestthatthechemicalcompositionofthemarineaerosolsisinfluencedbythreemajorsources:continentalairmasses,primaryoceanicemissions,andsecondarymarineaerosolsoriginatedfromoceanicemissions.Theresultsshowthat,awingtostronganthropogenicsulfuremissionsfromtheAsiancontinent,non-sea-saltsulfateconcentrationsintheNorthernHemisphere(thewesternNorthPacific)marineaerosolaresignificantlyhigherthanthoseintheSouthernHemisphere(theeasternIndianOcean).Aerosolnon-sea-saltsulfateconcentrationsappeartobeinverselycorrelatedwithaerosolnon-sea-saltchloridewhichshowssignificantlynegativevalues,indicatingthelossofchloridebyseasalts,inmostaerosolsamples.SincegaseousHClmaybeinvolvedinchemicalreactionsthatdepleteatmosphericozoneinthemarineboundarylayer(MBL),highlevelsofacidicnon-sea-salt-sulfatereleasedbyhumanactivitiesinthelowandmid-latitudesoftheNorthernHemispheremaybecomeanimportantpotentialcontributortothelossofatmosphericozoneintheMBL.
简介:Inthispaper,thecharacteristicsofdifferentformsofmildslopeequationsfornon-linearwaveareanalyzed,andnewnon-lineartheoreticmodelsforwavepropagationarepresented,withnon-lineartermsaddedtothemildslopeequationsfornon-stationarylinearwavesanddissipativeeffectsconsidered.Numericalsimulationmodelsaredevelopedofnon-linearwavepropagationforwatersofmildlyvaryingtopographywithcomplicatedboundary,andtheeffectsarestudiedofdifferentnon-linearcorrectionsoncalculationresultsofextendedmildslopeequations.Systematicalnumericalsimulationtestsshowthatthepresentmodelscaneffectivelyreflectnon-lineareffects.
简介:InthisstudyweassessedthecurrentstatusofcoralreefsalongtheSaudiArabiancoastoftheRedSea.AmongthethreegrowthformsofAcroporidcorals,thebranchingformswerefoundtodominateintheFarassanIslands(44.55%±11.10%cover)followedbytabularformsintheDogaIslands(rangingbetween18%±6.47%and18.30%±9.47%cover).DigitateformswererarelyfoundalongthecoastexceptatMaqna.Amongthefivegrowthformsofnon-Acroporidcorals,weobservedmaximumcoverofbranchingformsintheYanbuoffshorearea(58.89%±15.11%cover)followedbytheJeddahcoast(24.76%±14.04%cover).TheMilleporaspp.,anon-Scleractiniancoral,wasabundantatallthenear-shoresites,suchasJeddah(10.70%±8.21%)andAl-Wajh(9.81%±6.69%).Thelivecoralcover(includingbothScleractinianandnon-Scleractiniancorals)ofSaudiRedSeacoastwasseentobehigherinthenorthandgraduallydecreasetowardsthesouth.PrincipalComponentanalysisshowedthatthecontributionofAcroporidcoralswasgreaterinthesouthernregionthaninthenorthernandmiddleregions,butvice-versainthecaseofnon-Acroporidcorals.Bray-Curtisclusteranalysiscategorizedallthestudysitesintotwomajorclusterswith60%similarity.Amongthem,onecluster-formingsitesfromMaqnatoMasturah(Northernregion)andthesecondonecomprisedthemiddleandsouthernregions(JeddahtoFarassanIslands),andoneoutlierRabigh.
简介:OptimalstockingdensitieswereinvestigatedfortheseacucumberApostichopusjaponicusSelenkaunderfeed-supplementandnon-feed-supplementregimesinnetenclosuresfor333d.Substantialweightlossoccurredduringtheaestivationphase(AE).Decreasedgrowthrateswerealsoobservedduringthewinterphase(WT).Incontrast,seacucumbersshowedrapidgrowthduringthespring(SP)andautumn(AU)phases.Feedingregimesconsiderablyinfluencedthegrowthperformance,i.e.,seacucumbersgrewfasterunderfeed-supplementregimethanundernon-feed-supplementregime(P<0.05).Theaveragesurvivalratesofseacucumbersunderfeed-supplementregimewerehigherthanthoseundernon-feed-supplementregimeforboththeautumnphaseandspringphase,butthedifferenceswereonlysignificantforthelatterphase(P<0.05).ThefittedB-Ncurvesshowedthattheoptimalstockingdensities,intermsofnetproduction,were22.3ind.m-2forfeed-supplementregimeand14.1ind.m-2fornon-feed-supplementregime.
简介:Seacucumbers,ApostichopusjaponicusSelenka,werefeddietscontainingnon-immunostimulant(basaldiet),0.2%β-glucanand0.02%glycyrrhizininarecirculatorywatersystemfor45days,andsubsequentlychallengedwithVibriosplendidusbyinjectionat1.0×108cfu/seacucumberfor15days.Phagocyticcapacity(PC),intracellularsuperoxideanionproduction(ISAP),ly-sozyme(LSZ)activityandsuperoxidedismutase(SOD)activityinthecoelomicfluidwereanalyzedonthe0th,5th,10thand15thdaysafterinjection.Resultsshowedthatafterthe45-dayfeedingperiod,PC,ISAP,LSZactivityandSODactivityinseacucumbersfedwithdietaryβ-glucanorglycyrrhizinweresignificantlyhigherthaninthosefedwiththebasaldiet.Onthe5thdayafterinfection,alltheimmuneparametersexaminedintheseacucumbersinjectedwithV.splendidusdecreasedinvaluesignificantly.Onthe15thday,PC,ISAPandLSZactivityreturnedtolevelssimilartothoseonthe0thday.Fortheseacucumbersinjectedwithsaline,therewerenosignificantdifferencesinalltheimmuneparametersexaminedandinthecumulativemorbidityduringthe15-daychallengingtrial.AfterinjectingwithV.splendidus,thecumulativemorbidityofseacucumbersfedwiththebasaldietwassignificantlyhigherthanthosefedwithdietaryβ-glucanorglycyrrhizinwhenchallengedwithV.splendiduschallengedseacucumberfedwiththebasaldietwassignificantlyhigherthanthosefedwithdietaryβ-glucanorglycyrrhizin.Therewasnosignificantdifferenceincumulativemorbiditybetweenthedietaryβ-glucanandglycyrrhizintreatmentsovertime.