大气化学课件lecture1

物理学院大气与海洋科学系

物理北 Mondays15:00~17:00二教Officehours: M9-11am orby Coursewebsite: Final1CM+Jacob1,2CM+Jacob3,3CM+Jacob14CM+JacobCM+JacobCM+Jacob7CM+Jacob28CM+Jacob9对流层化学CM+Jacob11,10对流层化学CM+Jacob11,11312空气污染、空气污染问13酸雨、、持续性有机污染CM+Jacob）14415 自编 Jacob,D.J.,IntroductiontoAtmosphericChemistry,PretonUniv.Press,相关的学术一篇为，并另外找两篇与此相关的学术（中英文皆可）。针对这三篇学术科学问题做精确的说明和针砭性的讨论。所选论上课请关闭、计算机！WhatchemicalspeciesareintheWheredotheycomeWhatchemicalprocessesgoonintheWhataretheimpacts(ondifferentspatialandtemporalscales)?地球系统Earth1026 1022 1018~10191024

1021102610261022 1018~10191024 g-“Changesintheglobalenvironment limate,landproductivity,oceansorotherwaterresources,atmosphericchemistry,andecologicalsystems)thatmayalterthecapacityoftheEarthtosustain-U.S.GlobalChangeResearchActofSource:Earth’sradius

Massof Massof Meanvaluesfor30oN,MarchHydrostatic dPMagIdealGas a AssumeT=constant,Scale thesea-breezeeffect 1atm=101325Nm-2=101325Pa=1013.25MIXINGRATIO(dry[molMIXINGRATIO(dry[molmol-NitrogenOxygenArgonNeonOzoneHeliumMethaneKryptonAiralsocontainsvariableH2Ovapor(10-6-10-2molmol-1)andaerosolparticlesH2Ovaporchannel(6.5 U.U.U.Cloud&aerosolsarethevisibleAerosolscondensedphasesubstancesuspendedin ExcessLossof

YellowishExcessDustoffEast MixingNumber(specialcase:columnMassPartial(specialcase:relative𝐶𝑋

#moleofXmoleof

remainsconstantwhenairdensity robustmeasureofatmosphericForgases,fromtheIdealGas𝑃𝑉= 𝐶𝑋

#moleof=moleof

volumneofXgasunitvolumneTracegasconcentration1ppmv=1µmolmol-1=1x10-6molmol-11ppbv=1nmolmol-1=1x10-9molmol-11 =1pmolmol-1=1x10-12molmol-MIXINGRATIO(dry[molmol-NitrogenOxygenMIXINGRATIO(dry[molmol-NitrogenOxygenArgonNeonOzoneHeliumMethaneKryptonAiralsocontainsvariableH2Ovapor(10-6-10-2molmol-1)andaerosolparticlesHistoryofEarth’sTemperatureandatmosphericcompositionreconstructedfromAntarcticicecore:280280Petitetal. Wherearewe400Source:nX

#moleculesofXunitvolumeof

PropermeasurereactionopticalpropertiesofnXandCXarerelatedbytheidealgasA

na=airAv=Avogadro’snumberP=pressureR=Gas=Avk T=temperatureMX=molecularmassofAirnumberdensitynaatSTP(1atm,0oC)=Kroletal.Kroletal.Globalaverage[OH]atthesurface~106[moleculescm-3]WhatistheOHmixingratio(underSTP)?TraceTrace =nX0→Propermeasureforabsorptionorscatteringofradiationbyatmosphere THICKNESSOFOZONELAYERISMEASUREDASACOLUMNCONCENTRATION

Method:UVsolar OzoneScatteringbyEarthsurface=2.69x1016moleculescm-1“DobsonUnit(DU)”=0.01mmozoneatOzoneabsorption massof unitvolumeof

MXAvOftenusedforvanDonkelaar Unit:gm-3@200(1-USEPA:O3(8-hr)<0.075

(24-hr)<0.35gm-3;(annual)<15gm-

Agivenaerosolparticleischaracterizedbyitssize,shape,phase,chemicalcomposition–largenumberofMeasuresofaerosolconcentrationsmustbegiveninsomeintegralform,bysummin erallparticlespresentinagivenairvolumethathaveacertainpropertyTheaerosolsizedistributionmustbetreatedasacontinuous

TypicalaerosolbyvolumePM>1maremostlyfromprindmechanicalsources,e.g.dust,asbestosSecondaryandanthropogenicPMaremostly<1m,oftenclosetospherical0.2HumanHumanHair:100RelativeParticleVehicleEmission:0.2es:0.4CoalDust:2RoadDust:5Bacteria:10Aitken

CoarsedN/dlogr[#cm-SurfacedS/dlogdN/dlogr[#cm-SurfacedS/dlogr[m2cm-dV/dlogr[m2cm- Fine CoarseFromnucleationofprecursorgasmolecules(~10-3µm)formingnew

Aitkenparticles

Frommechanicals,e.g.machinegrindingAitkenrange(<0.1

range(0.1~2.5 Coarserange(>2.5 ParticlediameterDalton’s PXCX Propermeasureforphase(suchascondensationofwaterEvaporationofliquidwaterfromaNolid:watermoleculesescapefrompantoatmosphere(evaporation)Addaescawatermoleculescollideonlidandreturntosurface;collisionratemeasuresPH2Oeventually,fluxesca=fluxreturning:saturation(PH2O,SAT)cloudformationinatmosherePH2O>T CLAUSIUS-CLAPEYRONEQUATION:PH2O,SAT= H

B=-5310oTo=273oTRelativehumidity 𝑅𝐻

×Dewpoint:TemperatureTdsuchthatPH2O=Phasediagramforduetoaccumulationofwatervaporfromvolcanicoutgassingearlyinits…didnothappenonEarthbecausefartherfromSun;aswa ccumulateditreachedsaturationandprecipitated,formingtheoceansDrawmixinglines(dashed)todescribedilutionofyourbreathplumew/outsidePH2Oisplottedonlinearscaletodrawthemixing

Yourbreath37oC,≈100%RHnowarmoutsidecoldoutside AirpollutionhazeVisibilityislimitedbyhighconcentrationsofaerosolparticlesthathaveswollentolargesizesduetohigh(but<100%)relativehumidityP PH H H Hwatersaturationvaporpressureoverpureliquidwatersurface

ingreywatersaturationvaporpressureoveraqueoussolutionofwatermixingratioxH2OAnatmosphereofrelativehumidityRHcancontainatequilibriumaqueoussolutionparticlesofwatermixingratio

xH

PoPH

satisfysolubilityequilibriaConsideranaqueousseasalt(NaCl)particle:itmustxNaxCl xNaxCl xNaxClxH This1RH100(12Ks2 "deliquescenceAtlowerRH,theparticleisDeliquescenceRH;dependsonparticleSeinfeldandPandis,AtmosphericChemistryandPhysics,ChESA OnesurprisingconsequenceofglobalwarmingandCO2 isthechangeinsa liteorbits.Howmighttheychange? Oxygenhasafixedmixingratiointheatmosphere.Howwouldyouexpectitsnumberdensitymeasuredinsurfaceairtovarybetweendayandnight?Howwouldyouexpectitspartialpressuremeasuredinsurfaceairtovarybetweendayandnight?Wouldbreat