职位说明书销售总监

1、职位说明书销售总监SpeciesNatural processesanthropogenicPresent burden vs pre-industrialElements of climate affecting emissionsPrimary particles Mineral dust Wind erosionLand use change, industrial dustIncr.Changing winds and precipitationSea saltWind Changing windsBiolog. Part.Wind, biolog. processesAgricult

2、ure?Changing windsCarb. Part.Vegetation firesFossil fuel & biomass burningIncr.Changing precip.Secondary DMSPhytoplankton degradation More sulfateChanging windsSO2Volc emissionsFossil fuel comb.More sulfate NH3Microbial activityAgricultureMore ammonium nitrate NOxLightningFossil fuel comb.Incr.

3、nitrateChange in convective activityVOCVegetationIndustrial processesIncr. Org. aerosol Aerosol propertiesGas emissions leading to secondary aerosol Dimethylsulfide SO2 emissions from volcanoes Industrial SO2 emissions Nitrogen oxides and ammonia Volatile Organic compounds (VOC)(CH3)2S, Dimethylsulf

4、ide Recent global estimates of DMS flux from the oceans range from 8 to 51 Tg S a-1 This is 50% of total natural S-emissions (presently nearly equivalent to anthropogenic emissions, 76 Tg S a-1)- Differences in the transfer velocities in sea-to-air calculations Uncertainties are due to:- DMS seawate

5、r measurements (paucity of data in winter months and at high latitudes)DMS and Climate DMS is emitted by phytoplankton as a natural biproduct of metabolism Possibly related to radiation protection Gives sea water its characteristic smell Forms much of the natural aerosol (sub-micron particles) in oc

6、eanic air DMS is the major biogenic gas emitted from sea and the major source of S to the atmosphere. It contributes to the sulfur burden in both the MBL and FT.Figure adapted from Charlson et al. (1987) “Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate Nature, vol. 326, pp. 655-

7、661The CLAW Hypothesis(Charlson, Lovelock, Andreae and Warren, 1987) DMS from the ocean affects cloud properties and can feedback to the plankton community This acts to regulate climate by increasing cloud albedo when sea-surface temperatures rise.Sea-to-airtransportOcean DMSAtmosphereDMSAtmospheric

8、chemistryAerosolCloud Properties(albedo and lifetime)CloudphysicsSurfaceTemperatureand LightImpact of cloudon atmosphericradiationPlanktonCommunityConditions in thesurface oceanBiological andchemicalinteractionsBackdrop from the NOAA Central Library Photo CollectionDMS oxidation The atmospheric oxid

9、ation pathways that lead from DMS to ionic species (essentially sulfate and methanesulfonic acid, MSA, CH3SO3H) are complex and still poorly understood The first step to sulfate is SO2 SO2 is largely dominant vs MSA, except at high latitudes (reasons unclear) MSA is unique for tracing marine biologi

10、cal activity, since it has no other sourceAbout atmospheric SO2 SO2 has several sources: either natural: marine MSA and volcanism or anthropogenic: mining and fossil fuel burning Its oxidation ways to SO4- are still matter to investigation, in particular with the aid of S & O stable isotopes Thi

11、s can occur either in the gaseous phase by OH radicals or in the liquid phase by O3 or H2O2 . Generally gaseous phase process is dominant, except in regions of high sea salt concentrations0%50%100%Percent (%) change in concentrations (yearly average)Case A: SO2/SO42- concentration without sea-salt c

12、hemistry Case B: With sea-salt chemistrySO2 (decrease)SO42- (small increase)|100|CaseACaseBCaseA50%0%100%|100|CaseACaseBCaseAMar/Apr/MayJun/Jul/AugSep/Oct/NovDec/Jan/FebPercent (%) decrease (seasonal average):Biological regulation of the climate? (Charlson et al., 1987)DMSOHNO3SO2H2SO4OHNew particle

13、 formationCCNH2O2Light scatteringGas-phaseAqueous-phaseAqueous-phaseO3SO2 emissions from volcanoes (1) Volcanoes are a major natural source of atmospheric S-species Injections are generally occurring in the free troposphere Most active volcanoes are in the Northern Hemisphere (80%) The strongest sou

14、rce region is the tropical belt, in particular Indonesia Emissions are in the form of SO2, H2S and SO4- SO2 emissions from volcanoes (2) 560 volcanoes over the world are potential SO2 sources, but only a few have been measured Volcanic activity is sporadic, with a few cataclysmic eruptions per centu

15、ry Cataclysmic eruptions inject ash particles and gases (mainly SO2) into the stratosphere, where H2SO4 formed forms a veil ( Junge layer ) Volcano locationsContinuously erupting volcanoesAtmospheric impact of volcanoesSO2 relatively insoluble, resists tropospheric washoutInjected into the stratosph

16、ere in large quantities (Pinatubo, 1991 20 Tg)In stratosphere, SO2 oxidises to produce sulfuric acid aerosols (H2SO4)Conversion of SO2 to H2SO4 slow (months), aerosol cloud replenished months after eruption The total amount of volcanic tropospheric S-emissions is presently estimated at: Mean volcani

17、c sulfur emissions are of comparable importance for the atmospheric sulfate burden as anthropogenic sources because they affect the sulfate concentrations in the middle and upper troposphere whereas anthropogenic emissions control sulfate in the boundary layer.S-isotope measurements in central polar

18、 regions (i.e. in the free troposphere) seem to support the important role of volcanic sulfur Acid aerosols reside in the stratosphere for several yearsAerosol veils increase optical depth of the atmosphere (inc. optical depth of 0.1% = 10% reduction sunlight reaching Earth surface). Spread around t

19、he globe by stratospheric winds Injection of acid aerosols into stratosphere is thefundamental process governing the atmospheric impact of volcanic eruptionsVolcanic aerosol and global atmospheric effectsAtmospheric effects of volcanic eruptions1. Tropospheric cooling due to increased albedoEffects

20、of aerosols can be direct or indirectAlbedo increased indirectly when aerosols fall out of the stratosphereNucleate clouds in troposphere - increase albedooC) in the troposphere for periods of 1 to 3 yearsMagnitude of volcanic effects masked by natural variations (e.g. El Nino)2. Stratospheric warmi

21、ngAcid aerosols absorb incoming solar radiation, heating the tropical stratosphere, e.g. Mt. Agung (1963), El Chichon (1982), and Pinatubo (1991) all caused warming of the lower stratosphere of 2oC3. Enhanced destruction of stratospheric ozoneEl ChichonPinatuboLower stratospheric temperature (global

22、 mean)Localised heating in the stratosphere can influence how far volcanic aerosol veils spread, by influencing stratospheric wind patterns+3oC-3oC0oCStratospheric warmingVolcanoes do not inject chlorine into the stratosphere.Aerosols improve efficiency with which CFCs destroy ozone,by activating an

23、thropogenic bromine and chlorine, indirectly leading to enhanced destruction of stratospheric ozoneRelatively short lived - aerosols last only 2-3 years in the stratosphereReduction in ozone following the June 1991 eruption of Pinatubo Enhanced destruction of stratospheric ozoneSeveral factors combi

24、ne to determine whether a volcanic eruption has thepotential to influence the global atmosphere1. Eruption styleEnergetic enough to inject aerosols into the stratosphereLarger eruptions do not necessarily have greater effects Increased SO2 results in larger particles, not moreFall from the stratosph

25、ere faster, smaller optical depth per unit massvolcanic effects on the atmosphere may be self-limiting2. Magma chemistryImportance of acid aerosols means that large eruptions of sulphur-poormagma less significant than sulfur-rich magmase.g. Mt St Helens - sulfur poor - negligible global effectsAtmos

26、pheric “effectiveness3. LatitudeProximity to the stratosphere: smaller eruptions at high latitude can inject as much SO2 into the stratosphere as larger eruptions at lower latitudesStratospheric dispersal: Aerosols from tropical eruptions have the potential to spread around the globe (e.g Pinatubo).

27、 Atmospheric influence of eruption outside the tropics is contained within the middle and polar latitudes of the hemisphere of originAtmospheric“effectivenessAtmospheric processes are complex !Understanding how an atmospheric perturbation influences climate and weather is still problematic, even for

28、 largest eruptionsHowever, understanding how volcanoes effect climate necessary to isolate other forcing processesComparison of chronology of known eruptions and climatic data shed light on the ways climate responds to large volcanic eruptions Volcanic eruptions and climate1. The written recordCompa

29、re eruption chronologies with written records of unusualclimatic eventse.g. Benjamin Franklin (1784) During several months of the summer of the year 1783, when the effects of the Suns rays to heat the Earth should have been the greatest, there existed a constant fog over all of Europe, and great par

30、ts of North America. = 1783 - Laki fissure eruption, IcelandDisadvantages: record only a couple of thousand years, humans unreliable, eruption chronologies incomplete, geographical bias (e.g. no humans = no record)Making the connection2. Ice coresAcid aerosols fall on ice fieldsAccumulation of ice p

31、reserves information - acidity profileClimatically significant eruptions can be identified with great precisionAdvantages: objective, precise, records climatically significant eruptions onlyDisadvantages: Which eruptions and why? Only those with high sulfur contents. Geographical bias. HALF of known

32、 large eruptions not recorded in Greenland ice coresMaking the connection3. Tree ringsProxy witnesses to eruptionsTemperate trees record passage of seasons in growth rings - dendochronologyChanges in ring spacing, frost damage correlate with known eruptions Advantages: Trees, are old! Record extends

33、 back thousands of years. Objective, preciseDisadvantages: Tree growth sensitive to things apart from climate. Local environmental factors significantMaking the connection20 km3 of pyroclastic material in a Plinian column 40 km highAerosol veil circumnavigated the globe in 2 weeksInitially confined

34、to the tropics, later spread to higher latitudes inboth hemispheresCaused spectacular sunsets worldwide 20% fall in radiant energy reaching Europe after the eruptionAverage Northern Hemisphere cooling of 0.25oC, more pronounced athigher latitudes (-1oC)Case study: Krakatau, 188350 km3 of pyroclasts,

35、 Plinian column 43 km highAerosol veil reached London in about 3 monthsMany climatic effects attributed to Tambora1816 - the year without a summerinspired FrankensteinAnomalously cold winter in North America and EuropeWidespread crop failures, famineCase study: Tambora, 1815Global sulfur emissions G

36、lobal sulfur emissions latitude emissions.gifGLOBAL SULFUR EMISSION TO THE ATMOSPHERE (1990 annual mean)Chin et al. 2000Industrial SO2 emissions During the last decade, researchers from different countries have prepared separate country-level inventories of anthropogenic emissions (GEIA= Global Emis

37、sion Inventory Activity). In regions were local inventories were not available, estimates based on fossil fuel consumptions and population were calculated.In 1985: about 81% of anthropogenic sulfur emissions were from fossil fuel combustion, 16 % from industrial processes, 3 % from large scale bioma

38、ss burning and 1% from the combustion of biofuels, but these figures have to be revised for more recent years.The total amount for 1985 is estimated at :, accurate to 20-30%Anthropogenic sulfur emissionsFuture SO2 emissions in Asia are likely to be much lower than the latest IPCC forecastsSources of

39、 nitrogen oxidesand ammoniaAircraft0.5NOx: 32 TgN anthropogenic 11 TgN naturalFluxes in TgN/yearNitrogen oxides They are important in atmospheric oxidant chemistry They are precursors for nitric acid which is a contributor to atmospheric acidity and reacts with NH3 and alkaline particlesGlobal NOx e

40、missions (Tg/yr)A century of NOx emissions(van Aardenne et al., GBC, 15, 909, 2001)1890: dominated bytropical biomass burning1990: dominated bynorthern hemisphereindustrializationGlobal NOx from lightningAmmonia NH34. Ammonia is the primary basic (i.e. not acidic) gas in the atmosphere, and after N2

41、 and N2O, the most abundant nitrogen containing gas in the atmosphereThe significant sources of NH3 are animal wastes, ammonification of humus, emissions from soils, loss of fertilizer from soils and industrial sources see next tableThe ammonium ion, NH4+ is an important component of continental tropospheric aerosols (as is NO3-) forming NH4NO3NH3 is highly water soluble and therefore has a residence time in the troposphere of