极地上空的臭氧空洞-保护环境

Nov.3,20081Jan.10,2003-localnoon,Kiruna,SwedenNov.3,20082Jan.14,2003SouthernNorwayNov.3,20083PolarStratosphericOzoneDr.PaulA.Newman’sGoddardSpaceFlightCenterIPYWebcastNASAGSFCNov.3,2008Nov.3,20084OzoneBasicFactsO3=Ozoneiscomposedof3oxygenatoms.O3concentrationsaresmall(peakconcentrationsareabout10partspermillionatanaltitudeofabout32km(20miles).O3absorbsharmfulsolarultravioletradiation.Anecessaryconditionforlife.O3ismainlyfoundinthethestratosphere.O3atthegroundisaproblem!Inhalationofozoneforverysmallconcentrationscancauselungproblems.Mass:(BillionMetricTons)Sun1,9900,000,000,000,000,000Earth5,980,000,000,000Globalatmosphere5,300,000Globalozone3OxygenOzoneNov.3,20085AtmosphericComposition•Nitrogen78.1%•Oxygen20.9%•Argon0.9%•Water1.4%(tropics)0.2%(poles)0.0004%(stratosphere)•CO20.0360%•O30.001%(stratosphere)0.00001%(troposphere)Nov.3,20086180200220240260280300Temperature(K)020406080100Altitude(km)TroposphereStratosphereMesosphereThermosphereAtmosphericStructureAltitude(miles)100203040506081oF45oF9oF-27oF-63oF-99oF-135oFNov.3,20087020406080100Altitude(km)TroposphereStratosphereMesosphereThermosphereAtmosphericStructureAltitude(miles)1002030405060Airlinersflyat30,000-40,000feetNov.3,20088020406080100Altitude(km)TroposphereStratosphereMesosphereThermosphereAtmosphericStructureAltitude(miles)1002030405060ER-2fliesat70,000feetNov.3,20089020406080100Altitude(km)TroposphereStratosphereMesosphereThermosphereAtmosphericStructureAltitude(miles)1002030405060OxygenOzoneNov.3,200810QuickTime?andaTIFF(Uncompressed)decompressorareneededtoseethispicture.Ozone(partspermillion)020406080100Altitude(km)TroposphereMesosphereThermosphereOzoneFactsAltitude(miles)100203040506090%ofozoneisinthestratosphere02468Nov.3,200811Ozone(partspermillion)020406080100Altitude(km)StratosphereMesosphereThermosphereOzoneFactsAltitude(miles)10020304050600246810%ofozoneisinthetroposphereNov.3,200812Digression:DobsonUnits3mm=300DobsonUnits•TotalOzoneisameasureofthetotalcolumnamountaboveus.MeasuredinDobsonUnits•IfwebringalloftheozoneaboveusdowntotheEarth’ssurface•Thethicknesswouldbeabout3millimeters(~0.1inches)=300DobsonUnits(approximatelytheglobalaverage)•100DobsonUnits=1millimeterinthicknessTheDobsonUnitisaconvenientunitofmeasurementfortotalcolumnozone2¢10¢Nov.3,200813Ozone(partpermillion)020406080100Altitude(km)StratosphereOzoneFactsAltitude(miles)100203040506002468UVc-100%AbsorptionUVb-90%AbsorptionUVa-50%Absorption&ScatteringOzoneistheEarth’snaturalsunscreenNov.3,200814UVHealthFacts•UVpluses:producesvitaminDintheskin-necessarytomaintainlevelsofcalciumandphosphorus(10-15minutestwiceaweek)•UVminuses:–Eyedamage:cataracts,photokerititus(snowblinding),ocularcancers–Skincancers:basal,squamous,melanoma–photoaging–DamagetovariouslandspeciesDamagetoaquaticspecies–IncreasedpollutionlevelsinurbanenvironmentsQuickTime?andaTIFF(Uncompressed)decompressorareneededtoseethispicture.QuickTime?andaTIFF(Uncompressed)decompressorareneededtoseethispicture.CataractMelanomaMexicoCityNov.3,200815LargepolarozonelossesresultfromchlorineandbrominecompoundsthataremainlyhumanproducedNov.3,200816CFC-12releasedintroposphereCarriedintostratosphereinthetropicsbyslowrisingcirculationCFC-12photolyzedinstratospherebysolarUV,releasingClClcatalyticallydestroysO3ClreactswithCH4orNO2toformnon-reactiveHClorClONO2PolarlossChlorinePathwayNov.3,20081716%32%23%12%7%5%1%4%03400300020001000(CH3CCl3)(e.g.,HCFC-22=CHClF2)(CCl2FCClF2)NaturalsourcesOthergasesMethylchloroformHCFCsCFC-113Carbontetrachloride(CCl4)CFC-11(CCl3F)CFC-12(CCl2F2)Methylchloride(CH3Cl)0201510515%27-42%5-20%20%14%4%Methylbromide(CH3Br)Halon-1211(CBrCIF2)Halon-1301(CBrF3)OtherhalonsVery-shortlivedgases(e.g.,bromoform=CHBr3)SourceGases•ClismuchmoreabundantthanBr,but…•Brisabout60timesmoreeffectiveatO3destructionFromOzoneFAQ-see[1998],AllCFC-113fromSteveMontzka(flasksbyGC/MS),andrecentupdatesofallothergasesfromGeoffDutton(insituGC).50years102years5years42years85yearsCFC-11CCl4CFC-113CFC-12CH3CCl3Nov.3,200819PolarStratosphericCloudsCentral,SwedenJanuary14,2003-P.NewmanNov.3,200820Solomonetal.(1986),WofsyandMcElroy(1986),andCrutzenandArnold(1986)suggestreactionsoncloudparticlesurfacesasmechanismforactivatingChlorineHClClONO2HNO3Cl2Cl2iseasilyphotolyzedbyUV&blue/greenlightHNO3issequesteredonPSCAntarcticozoneholetheoryNov.3,200821PolarOzoneDestruction1.O3+ClClO+O2Onlyvisiblelight(blue/green)neededforphotolyzingClOOClNooxygenatomsrequiredNet:2O3+h3O22O33O23.ClOOCl+h2Cl+O22.2ClO+MClOOCl+MNov.3,200822AntarcticMeasurementsAuroraoverHalleyBayStation,Antarctica,75.6ºS26.5ºEBruntIceShelf,CoatsLand105daysofcontinuousdarkness,twiceperyearre-supplyPopulation:65insummer,15inwinterNov.3,200823OctoberAntarcticOzonepre-1985Nov.3,200824OctoberAntarcticOzoneNov.3,200825TOMS-August31,2003Orange/Ye