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MODELING THE EFFECTS OF ANTHROPOGENIC SULFATE IN CLIMATE CHANGE BY USING A REGIONAL CLIMATE MODEL

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MODELING THE EFFECTS OF ANTHROPOGENIC SULFATE IN CLIMATE CHANGE BY USING A REGIONAL CLIMATE MODEL

    MODELING THE EFFECTS OF

    ANTHROPOGENIC SULFATE IN

    CLIMATE CHANGE BY USING A

    REGIONAL CLIMATE MODEL

Vo1.9No.2JOURNALOFTROPlCALMETEOROLOGYDecember2003

    ;ArticleID:l006-8775(2003102-0l73-08

    ;MoDELINGTHEEFFECTSoFANTHRoPoGENICSULFATEIN

    ;CLIMATECHANGEBYUSINGAREGIoNALCLIMATEMoDEL

    ;GAOXue-jie(高学杰),LINYihua(林一骅),ZHAOZong.zi(赵宗慈)

    ;(I.NationalClimateCenter,Bering10008IChina;2.InstituteofAtmosphericPhysics,ChinaAcademyof

    ;Science,Bering100029China)

    ;ABSTRACT:EfiectsofaerosolwithfoCUSonthedirectclimateefrectOfanthmpogenicsulfateaerosolunder2

    ;×CO,conditionwereinvestigatedbyintroducingaerosoldistributionintothelatestversionofRegCM2.Two

    ;experiments,firstl’Hn(2×CO,+0acrosolconcentration)andsecondran(2×CO+aerosoldistribution),were

    ;madefor5yearsrespectively.PreliminaryanalysisshowsthatthedirectclimateeffectOfacgosolmightcausea

    ;decreaseofsurfaceairternperature.ThedecreasemightbelargerinwinterandinSouthC:hina.Theregional?

    ;averaledmonthlyprecipitationmightaisodecreaseinmostofthemonthsduetotheefrect.Theannualmean

    ;changeofprecipitationmightbeadecreaseinEastandanincreaseinW_estChina.Butthechangesofboth ;temoeratureandprecipitationsimulatedweremuchsmallerascomparedtothegreenhouseeffect. ;Keywords:greenhouseeffect;regionalclimatemodel;regionofChina;anthropogenicsulfateaerosol ;CLCnumber:P461.8Documentcode:A

    ;Beingallimportantcompositionoftheatmosphere.aerosolattractsincreasingattentionfrom ;thescientificcommunityinrecentyears.togetherwiththeradiativeforcingitcausesandeffects ;itimposesontheclimatesystem.Theanthropogenicaerosolaffectstheclimatebothdirectlyand ;indirectly.Theclimateisdirectlyaffectedwhensolarshortwaveradiationisscatteredand ;absorbedinwhatisknownasthe’’umbrellaeffect”.whichcanbedatedbacktoasearlyasmore

    ;than70yearsago:itisindirectlyinfluencedwhenopticcharacteristicsandlifecyclesare ;alteredthroughthecloudcondensationnuclei(CCN),whichwasfirStknowninthel970’’.s”.The

    ;twoeffectsoftheaerosolareiusttheoppositetothatofgreenhouseeffect,fortheradiative

    ;forcingvalueisaboutonethirdormoreaspowerfulasthelaner.weakeningorevenoffsettingits ;ect’.Itisnotaffordable.therefore.toignoreaerosolinstudyingtheeffectofhumanactivity

    ;onclimate.

    ;Therearequiteanumberofstudiesoverseasaddressingtheissueoftheaerosoleffect

    ;generalcirculationmodelsareincorporatedandeffectsareestimatedonsuchclimateelementsas ;airtern0eratureandprecipitation.Reference41givessimulatedresultsofsomemodelsforthe

    ;EastAsiaregion.

    ;Domestically,theresearchontheaerosoleffectalsobeganearly.Theenergyequilibrium ;modelwasusedtoestimatetheradiativeforcingeffectoftheaerosolanditseffectonair ;temperature..’.Recentyearswitnessedtheintroductionofaerosoltoclimatemodels”.

    ;Generallyspeaking.however,moreworkshouldbedonetointroduceaerosolto3Datmospheric

    ;Receiveddate:2002-l1-l8:reviseddate:200308.29

    ;Foundationjtem:NationalNaturalScienceFundamentalofChina(40l250l4}:KnowledgelnnovationProgram

    ;oftheChineseAcademyofSciences(KZCXl-SW-0I-l6):SupportingFundforIPCCofChinaMetcomlogical

    ;Administration

    ;Biography:GAOXue-jie(1966

    ),malvinghighresolutionanddetailedphysicalprocesses.regionalclimatemodelsarewidely ;appliedinthestudyofclimateoverlimitedareas.Onthebasisofpreviouswork’.anthropogenic

    ;sulfateaerosolanditseffectonshortwave(knownasdirectclimaticeffect.tobecalledaerosol ;effectintherestofthetextforbrevity)areaddedtoourregionalclimatemodelandnumerical ;experimentsareconductedontheaerosoleffectonregionalclimateinC:hinawithCO,doubled ;inquantity.

    ;ThemodelinquestionisthelatestversionoftheRegCM2modelreleasedbythelCTP,the ;AbdusSalamlnternationalCenterforTheoreticaPhysics.Whatisimprovedovertheold

    ;version…ismainlytheradiationprocess.becausetheradiationschemehasbeenreplacedas

    ;themodelchangesfromCCM2toCCM3.Withadditional”backgroundaerosol”(sulfateaeroso1).

    ;thenewschemefoIlowsthecalculationmethodofJ.Kiehletalanddeterminestheoptic ;characteristicsofthesulfateaerosolforthel8shortwavesectionsdividedbythemodel(the ;extinctionperunit,singlescatteringalbedoandasymmetricparameter).Theircorresponding ;valuesaredeterminedinshortwavecalculation.Theconcentrationofaerosoltakesanear- ;constantvaluewhichisaddedatthelowestthreelayersofthemodelandisusedasthe ;backgroundaeroso1.Thevalueisusefulforreferenceinexperimentingsensitivitytoclimate.but ;diersmuchfromtheobservation.

    ;Duetothepresentlimitationofconditions.asystematicdatasetispresentlynotavailableas ;farasthetemporalandspatialdistributionofaerosolisconcerned.Theproblemisusuallysolved ;byhavingaccesstotheabovedatasetthroughdevelopmentofachemicaltransmissionmodel ;(CTM)thatdescribesindetailstemporalandspatialdistributionofaerosolontheregionalor ;globalscale,basedontheobservationsnowavailable.

    ;111eanthropogenicsulfateaerosoldatausedintheworkareobtainedusingtheabove ;technique,whichareprovidedbyFeichtereta1.fromtheMax.PlanckInstitutefor ;Meteorology,Germany.Intheoriginaldata,thehorizontalresolutionis3.75lat.×3.75long. ;andthereare16layersintheverticaldirection.AdetailedanalysiswasmadebyZhangetal.

    ;Fig.1(a&b)givesthedistributionofaerosolatthelowestlayerofthemodel-determineddomain ;inJanuaryandJuly.Estimatesdiforfuturevariationofaerosolemission.Withthea$$unlption ;thatittendstoincreaseintheregionofChina.therewillbe30%moreaerosolwhenthecontent ;ofCO2isdoubled.

    ;Fig.1Loxx’est-modellayerdistributionofanthropogenicsult’ateaerosolforJan.

    a1andJu1.tb1.Unit:ttg/m’

    ;

    ;No2GAOXuejief高学杰),LINYi.huaf林一桦)andZHAOZong-ci(赵宗慈)175

    ;Similartopreviouswork..

    ;theinitialandlateralfieldsoftheregionalclimatemodelare

    ;takenfromaCO,doublingexperimentwiththeCSIROR2L9AOGCMofAustralia.Thefirst

    ;experimentofthemodelistodoublethecontentofCO,,whichisequivalenttoseUingthe ;aerosolvaluezero.i.e.ignoringtheeffectofaerosol;thesecondexperimentisonethatismade ;withanthropogenicsulfateaerosolwhenCO,isdoubled,inwhichthelatelyavailable”observed”

    ;aerosoldataareaddedtoallgridpointsandlayersofthemodelforclimatologicalintegration.For ;theintegratedregionalmodel,theCO2isdoubledcorrespondingly.Thelengthofintegrationis ;fiveyearsinbothexperimentsandtwoaverage5.yeardifie:rencesbetweenthesecondandfirst ;experimentsareconsideredtheclimaticroleoftheaeroso1.InthesectionsfoIlowed,theresults ;willbeusedtostudybrieflytheeffectofaerosolonsurfacetemperatureandprecipitationin ;ChinawiththecontentdoubledforCO,.

    ;3EFFECTONSURFACEAIRTEMPERATUREINCHINA

    ;Individualclimaticelementsareinterpolatedtol6OobservationstationsacrossChina.First, ;regionalmeansurfacetemperaturesaredeterminedonamonthlybasis,whichreflectsthe ;additionofanthropogenicsulfateaerosolanddoublingoftheCO2Ievel(Fig.2).Itshowsthatthe ;aeroso1.addedmodeIreportswidespreadreductionofsurfacetemperaturethoughthemonthly ;amountisnormallylessthan-0.2.CandannualmeanfaIlisIessthan_0.1.C.Itindicatesthatthe

    ;directeff-ect0fanthropogenicsulfateaerosolcausesthetemperaturetodropinChina,butby ;muchsmalleramplitudethanwhatthegreenhouseeffectincreasesit(withtheannuaImeanof ;2.5.C1.ThefigurealsotellstheseasonaIinconsistencyintemperaturevariationcausedbythe ;aerosolintheregionofChina,andslightrisesevenoccurinJune.Itmaybecontributedbythe ;factthattheaddedaerosoIresultsinchangesinmode1.derivedphysicalquantitiesIikeclouds ;(oneofindireetclimaticeffects)tocomplicatethesurfacetemperaturechangeandcause ;inconsistentresponsefromtemperaturefrommonthtomonth,aswellasaffectingshortwave ;radiation.Itisanissuethatrequiresmorestudytoconfirm.

    ;O.2

    ;0?1

    ;?O

    ;

    ;O?1

    ;-0.2

    ;.........

    ;l23456789l0lll2month

    ;Fig.2VariationsofmonthlymeansurfacetemperatureovertheregionofChinawithaerosolincluded ;Tab.IgivesthemonthlyspatiaIconcentrationofaerosolfortheI60stationsinChinaandits

;correlationwiththemonthlymeansurfacetemperature.

    ;1tisseenfromthetablethatthecorrelationcoefficientis-0.29f0rtheyearlymean,showing ;thesurfacetemperatureinsomedegreeofnegativecorrelationwithaerosoIconcentration.i.e.the ;highertheconcentrationofaeroso1.thelargerthetemperaturefaIlitsocaused.Thecorrelationis ;themostobviousinNovemberAprilofthewintertime.withthecoefficientashighas-4).55on ;average;itismuchlessobviousinMayOctoberofthesummertime,withthemeancoefficient

    ;iustalittlebelowzero(0.04).FortheI6Opoints,thevalueofspatialcorrelationisabout0.2 ;whenthelevelofconfidenceis0.99.Thewintertimecorrelationbetweenthemisusual1)aboxe ;

    ;I7(1J0URNAL0FTR0PlCALMETEOROLOGYVol9

    ;thelevelintheconfidencetestwhileitisnotmostofthetime

    ;Tab.ICoefficientsofthecorrelationbetweenregionalaerosolconcentrationinChinaandsurfacetemperature

    ;Nextisabriefdiscussionoftheplanedistributionofseasonalsurfacetemperaturevariation ;intheregionofChinawiththeIeveIofCO,doubledandaerosoIincluded.

    ;TemperaturevariationinChinacausedbywintertimeaerosol(Fig.3a)isgenerallydecreasing ;nationwide,morepronouncedlysoinregionssouthoftheChangjiangR.(Yangtze),thedrop ;beingusuallybelow-0.2.C.butlCSSSOinNortbeastChinawiththefaIJlessthan_0.1.C.In ;China.precipitationisusuallylessinwinterandsoiscloudage,becausetemperatureisdirectly ;reducedinmostpartofthecountryasaresultoftheblockingandreflectionofshortwave ;radiationbyaeroso1.Thedistributionoftemperaturefallcanalsobeimmediatelyassociatedwith ;thatofaeroso1.Inotherwords.aerosolishigherincontentinsouthemthaninnorthemChina ;(Fig.1a,andthuscauseslargerreductionoftemperatureinsouthernthaninnorthernChina.One ;noteworthypointisthatthereisalsoalarge-valueareaoftemperaturefallinthecentraland ;westernChina,whereaerosolisusuallysmallincontent.Itshowsthataerosolcanbringabout ;changesinclimatologicalelementsinotherregionsviachangesincirculation,inadditiontolocal ;effect.Itneedsmorestudyforexplanation.Winteristheseasoninwhichregionallyaveraged ;temperature,.D.14.C,isJargerthantheotherthreeseasons.

    ;Fig.3EffectofaerosolonsurfacetemperatureintheregionofChinainwinter(a)andsummer(b) ;Thedescendingtrendcontinuesinautumn(figureomitted).thoughthecenterhasnow ;shiftedtoareasfromthelowerreachesoftheChangjiangR.ToJiangsuandShandongprovinces ;whiletheNortheastChinaremainsaregionwherethetemperaturedropisrelativelysmal1. ;Additionally,temperatureisrelativelylowinthesouthernpartofChina.Oneofthe ;characteristicsofspringtemperaturevariationjsthatsomesporadictemperature.ridingspots ;begintoappearwithintheregion.Theregionallyaveragedtemperaturedropbecomessmallerfor ;theseason.being-0.12.C.

    ;Withtheincreaseofcloudageinsummer,theefrectofaerosolonairtemperatureinChina ;becomesmorecomplicatedascomparedwithwinterandspring.AsshowninFig.3b.the ;temperaturemainlydecreasesasinthepreviousseasons,thoughwithmuchsmalleramplitude ;withthevaluebasicallywithin-0.1.C.Temperaturechangesalternativelybetweenpositiveand ;

    ;

    ;f)2(iAf)Xue.1ief高学杰),I.INYi.hua(林一桦)andIAOZong-ci(赵宗慈)177

    ;negativeinNorthernChina,thoughincreasingisthemaintrend.Thetemperaturechangeis

    ;mainlyofdecreaseinXinjiangandareasaroundit.probablyduetodryerelimateandless ;amountofcloudthere.ThetemperaturevariationiSaweaknegative,0.0I,thelowestjnalI

    ;SeaSOnS.

    ;Withthedecreaseofcloudagejnautumn.temperaturemainlydecreasesinChina.The ;distributioniSsimjlartothatofwinter.i.e.thedropjSlargerinsouthernthaninnorthernChina. ;ThetemperaturechangeiS-0.09.Cf0rregionalmeanintheseason.

    ;Fig.4givesthedistributionoftemperaturechangeoverthecourseoftheyear.Exceptfora ;feWstations,thebasictrendiSdecreasing,withlargeramplitudeinthesouthandnorthwestparts ;ofthenation,thoughthemagnitudeislow,exceptfortheareassouthoftheChaniangR.and

    ;partofNorthwestChinawherethevalueiSbelow-0.IoC.whichiSmuchsmallerthanthe ;changeinducedbygreenhousegases.

    ;Fig.4VariationsofannealmeantemperatureoverChinacausedbyanthmpogenicsulfate.Unit:x10oc ;4EFFECToNPRECIPITATIoNINCHINA

    ;Ascomparedtotemperature,anthropogenicsulfateaerosolcausesmorecomplicated ;changesinprecipitation.

    ;Firstofall,withCO2doubled,monthlymeanprecipitationchanges(%)arestudiedforthe ;l60weatherstationsinChina.FromFig.2.weknowthataerosolmainlycausestheprecipitation ;todecreaseinChina,thoughwiththeamplituderangingfrom-I%to5%;thevariationison1)’

    ;

    ;1%f0rmonthlymeanacrosstheyear.evenwithatendencytoincreaseinJune. ;Tab.2VariationofmonthlymeanprecipitationinChinaWiththeinclusionofaerosol(unit:%1 ;Monlh4?569l0Ill2Mcan

    ;Precip’tati0n

    ;

    ;252.31.1.16-o52OI4-4701-o93.8...61.2

    ;changes

    ;Seasonalchangesresultingfromaerosolinclusioninthetn~xlelareasfollows.Inwinter ;(,Fig.5a).itcausesthereductionofprecipitationOVerextensiveregionofChina.withthelarg2er ;centerovertheJiaodongPeninsulaandsurroundingareasandatemperaturehalloflOo0: ;

    ;‘SJOURNALOFTROPICALMETEOROLOGYV0I9

    ;precipitationincreasesoversomeregionsbutwithsinailvalues,usuallybelow5%.Thevariation ;is-1.7%fortheregionalmean.

    ;Thevariationismorecomplicatedinspringprecipitation,whichisbasicallyoverthe ;NonheastandNorthChinaregionsandonthedecreasemainly.andthedroprateislargerin ;somepartsthanintherest,withthevalueover10%;theincreasinganddecreasingareashavethe ;samedistributionsouthoftheChangjiangR.butdecreasingisthemaintrend;largepartof ;centralChinashowsanincreasingtrend,withsomestationsashighas20%.Andthevariationis ;-

    ;0.90/0fortheregionalmean.

    ;Fig.5SameaSFig.3butforprecipitation.Unit:%

    ;Insummer(Fig.5b),exceptforafewregions,precipitationdecreasesoverlargeareassouth ;oftheChangiiangR.andeasternpartofNorthChinabyasmuchas15%ormoreinsome ;locations;precipitationmainlyincreasesinNorthwestChina.Thevariationis1.4%forthe

;regionalmean.

    ;Forthevariationofprecipitationinautumn(figureomitted),precipitationmainlydecreases ;intheeasternpartofChinaexceptforthecoastalareainthesouth.ItalsodecreasesinNorthwest ;China.JnregionsfromtheInnerMongoliaAutonomousRegiontotheGreatBendofYellowR. ;andfromFujian,GuangdongtoGuangxi,precipitationincreases.Thevariationis1.0%forthe

    ;regionalmean.

    ;ThedistributionofprecipitationchangeaveragedovertheyearisgiveninFig.6.Withthe ;doublingofCO,.theeffectofsulfateaerosolissuchthatitwilIleadtoprecipitationdecrease ;overextensiveareassouthoftheChangJiangR.andeasternpartofNorthChinabutincreaseover ;NorthwestChina;eitheroftheincreaseordecreaseissmal1.usuallywithinl0%.Thevariationis ;only1.2%f0rthenationalmean.whichisalsomuchsmallerthanthechangebroughtaboutby ;greenhousegases.

    ;1ngenera1.anthropogenicsulfateaerosolcandirectlyJeadtothereductionofprecipitation ;averagedoverChina.thoughwithsmallamplitude.Thephysicalrelationsarecomplicatedfor ;processesfromdirectradiationeffectduetoaerosoltoprecipitationchanges,includinganumber ;ofnon.1ineareffects.Muchstudyisneededbeforewehavephysicallysoundexplanation. ;5CoNCLUSloNSANDDlSCUSSIONS

    ;ThelatestversionofRegCM2modelisfedwithaerosoldataforexperimentsonchangesin ;temperatureandprecipitationinChina,whicharemainlysubjecttothedirectclimaticeffectof ;

    ;No.2GAOXue-iie(高学杰).LINYi-hua(林一桦)andZHAOZong-ci(赵宗慈)179

    ;anthropogenicsulfateaerosolandthe

    ;doublingofCO,,withorwithoutaeroso1?

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