Atmospheric pollution in the Arctic

160 Pages·2011·20.21 MB·English

Atmospheric pollution in the Arctic:
Sources, transport, and chemical processing
A dissertation presented
by
Jenny A. Fisher
to
The Department of Earth and Planetary Sciences
in partial fulfillment of the requirements
for the degree of
Doctor of Philosophy
in the subject of
Earth and Planetary Sciences
Harvard University
Cambridge, Massachusetts
August, 2011
(cid:13)c 2011byJennyA.Fisher
Allrightsreserved.
iii
DissertationAdvisor Author
ProfessorDanielJ.Jacob JennyA.Fisher
Atmospheric pollution in the Arctic:
Sources, transport, and chemical processing
Abstract
This dissertation applies a global chemical transport model (GEOS-Chem) together with
ground-based, aircraft, and satellite observations to quantify the sources, transport path-
ways,andchemicalprocessingoftroposphericpollutionintheArctic.
Asiananthropogenicemissionsareshowntobethedominantsourceofcarbonmonox-
ide (CO) pollution throughout the Arctic troposphere, except near the surface where Euro-
pean anthropogenic emissions are similarly important. Despite anomalously large fires in
spring 2008, biomass burning is found to contribute little to mean CO during that period.
AIRS satellite data are used to demonstrate a link between El Nin˜o and Asian pollution
transport to the Arctic, with transport hindered in 2008 due to a weakened Aleutian Low
associatedwithLaNin˜aconditions.
Sulfate-ammonium aerosol in the Arctic is found to derive from a more complicated
mixofsources. EuropeanandEastAsianemissionsareimportantbutnotdominantsources
ofsulfate. AnthropogenicemissionsfromWestAsia(RussiaandKazakhstan)areshownto
providethelargestsourceofsulfatetotheArcticlowertroposphereinwinter. Ammonium
iv
is mostly from European and East Asian sources. In spring 2008, a large contribution
from boreal fires resulted in a more neutralized aerosol in the free troposphere than at the
surface. AerosoltransportedtotheArcticfromEastAsiaandEuropeisfoundtobemostly
neutralized,whileWestAsianandNorthAmericanaerosolishighlyacidic. Recentgrowth
of sulfur emissions in West Asia may explain observations of increasing aerosol acidity in
Alaskaoverthepastdecade.
MercuryintheArcticshowsadifferentseasonalityfromotherpollutants,withaspring
minimum driven by bromine chemistry over sea ice followed by a summer maximum.
GEOS-Chem simulations of surface observations are used to argue that the summer peak
cannot be explained by atmospheric transport, re-emission from snowpacks, or ocean ki-
netics. Instead,RussianriversareproposedtoprovidealargefluxofmercurytotheArctic
Ocean in spring-summer, with subsequent evasion to the atmosphere driving the observed
summer peak. The Arctic Ocean then provides a net source to the atmosphere, with rivers
thedominantmercurysourcetotheArcticenvironment.
Contents
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
TableofContents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
ListofFigures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
ListofTables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
CitationstoPreviouslyPublishedWork . . . . . . . . . . . . . . . . . . . . . . x
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
1 Overview 1
1.1 TransportofpollutiontotheArctic . . . . . . . . . . . . . . . . . . . . . . 2
1.2 SourcesandpropertiesoftheArcticaerosol . . . . . . . . . . . . . . . . . 3
1.3 Atmosphere-oceancyclingofArcticmercury . . . . . . . . . . . . . . . . 5
1.4 Outlineandmajorresults . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Source attribution and interannual variability of Arctic pollution in spring
constrainedbyaircraft(ARCTAS,ARCPAC)andsatellite(AIRS)
observationsofcarbonmonoxide 13
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2 Modeldescription . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3 COobservationsandconstraintsonsources . . . . . . . . . . . . . . . . . 24
2.4 SourcesofArcticpollutioninApril2008 . . . . . . . . . . . . . . . . . . 31
2.5 VariabilityofArcticpollutionobservedbyAIRS . . . . . . . . . . . . . . 36
2.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3 Sources, distribution, and acidity of sulfate–ammonium aerosol in the Arctic
inwinter–spring 59
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
3.2 GEOS-ChemSimulation . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3.3 Testingemissioninventorieswithwetdepositionfluxdata . . . . . . . . . 69
3.4 SimulationandsourceattributionofArcticsulfate . . . . . . . . . . . . . . 74
3.4.1 Aircraftdata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.4.2 Surfacedata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
vi
3.4.3 BudgetfortheHighArctic . . . . . . . . . . . . . . . . . . . . . . 87
3.5 SimulationandsourceattributionofArcticammonium . . . . . . . . . . . 89
3.5.1 Aircraftdata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.5.2 Surfacedata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.5.3 BudgetfortheHighArctic . . . . . . . . . . . . . . . . . . . . . . 92
3.6 AcidityoftheArcticaerosol . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.6.1 Aircraftdata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.6.2 Surfacedata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.6.3 Pan-Arcticperspective . . . . . . . . . . . . . . . . . . . . . . . . 98
3.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
4 LargemercuryevasionfromtheArcticOceaninsummer: asourcefrom
circumpolarrivers? 119
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
4.2 GEOS-Chemmodeldescription . . . . . . . . . . . . . . . . . . . . . . . 123
4.3 InterpretingtheseasonalvariationofmercuryintheArctic . . . . . . . . . 126
4.4 BudgetofmercuryfortheArcticOcean . . . . . . . . . . . . . . . . . . . 137
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
List of Figures
2.1 April2008carbonmonoxideemissions . . . . . . . . . . . . . . . . . . . 22
2.2 2001-2008 monthly mean fire counts over Russia and Kazakhstan from
MODIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3 ObservedandmodeledCOconcentrationsduringARCTASandARCPAC . 26
2.4 Observed and modeled vertical distributions of CO concentrations during
ARCTASandARCPAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5 ObservedandmodeledCOcolumnsatEureka,Nunavut,Canada . . . . . . 30
2.6 MeanApril2008COcolumnsobservedbyAIRSandsimulatedbyGEOS-
Chem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.7 MedianverticaldistributionalongflighttracksofGEOS-ChemCOtagged
bysourceregionandtype . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.8 GEOS-ChemmeanCOmixingratiosintheArcticinApril2008 . . . . . . 34
2.9 Russianbiomassburningeventon16April2008sampledbytheARCTAS
aircraftandtheAIRSsatellite . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.10 Backwardandforwardtrajectoriesfromthe16April2008plume . . . . . . 39
2.11 Europeanpollutioneventon9April2008sampledbytheARCTASaircraft
andtheAIRSsatellite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.12 Backwardandforwardtrajectoriesfromthe9April2008plume . . . . . . 41
2.13 2003–2008AprilCOcolumnsfromAIRS . . . . . . . . . . . . . . . . . . 42
2.14 2003–2008AprilsealevelpressuresfromGEOS-5 . . . . . . . . . . . . . 43
2.15 Year-to-yearvariabilityofthemeanAprilAIRS-observedCOcolumnover
AlaskaandmeanOceanNin˜oIndex(ONI) . . . . . . . . . . . . . . . . . . 45
2.16 GEOS-Chem Asian fossil fuel CO with April 2005 versus April 2008 me-
teorology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.1 January-May2008GEOS-ChememissionsofSO andNH . . . . . . . . 66
2 3
3.2 SulfateandammoniumwetdepositionfluxesoverNorthAmerica,Europe,
andEastAsiainApril2008 . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3.3 Regionsusedformodelsourceattribution,alongwithflighttracksandsur-
facesitelocations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.4 ComparisonofmodeledandobservedsulfateandammoniumduringARC-
TASandARCPAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
viii
3.5 MeanverticaldistributionsofsulfateandammoniumduringARCTASand
ARCPAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.6 January-Maymonthlymeansulfateandammoniumconcentrationsobserved
andmodeledatArcticsurfacesites . . . . . . . . . . . . . . . . . . . . . . 84
3.7 GEOS-ChembudgetsofsulfateandammoniumaerosolsintheHighArctic
inAprilandJanuary-February2008. . . . . . . . . . . . . . . . . . . . . . 88
3.8 Scatterplots of observed and modeled acid aerosol neutralization during
ARCTASandARCPAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
3.9 Scatterplot of the aerosol neutralization fraction for aerosol originating
fromthefourmajoranthropogenicsourceregions . . . . . . . . . . . . . . 97
3.10 2004-2008aerosolneutralizedfractionobservedatsurfacesites . . . . . . 98
3.11 Maps of mean aerosol neutralized fraction in surface air and at 5 km alti-
tudeforAprilandJanuary-February2008 . . . . . . . . . . . . . . . . . . 100
4.1 Mean observed seasonal variation of elemental mercury in surface air in
theArcticandatnorthernmid-latitudes . . . . . . . . . . . . . . . . . . . 122
4.2 ObservedandmodeledseasonalvariationofmercuryinArcticsurfaceair . 128
4.3 ModeledseasonalvariationoftotalmercuryandmercuryfluxesintheArc-
ticOcean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
4.4 Monthly water discharge of the eight largest circumpolar rivers into the
ArcticOcean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
4.5 AnnualbudgetofmercuryfortheArctic . . . . . . . . . . . . . . . . . . . 138
List of Tables
2.1 GlobalCOsourcesforApril2008usedinGEOS-Chemsimulations. . . . . 20
2.2 CorrectionfactorstopriorCOcombustionsourcesinGEOS-Chem . . . . . 28
3.1 GlobalSO andNH emissionsfor2008. . . . . . . . . . . . . . . . . . . 67
2 3
3.2 Sulfateneutralizationratiosbysourceregion . . . . . . . . . . . . . . . . . 73
x
Citations to Previously Published Work
Chapters2and3haveappearedpreviouslyinthefollowingpapers:
Fisher,J.A.,D.J.Jacob,M.T.Purdy,M.Kopacz,P.LeSager,C.Carouge,C.D.
Holmes, R.M. Yantosca, R.L. Batchelor, K. Strong, G.S. Diskin, H.E. Fuel-
berg, J.S. Holloway, E.J. Hyer, W.W. McMillan, J. Warner, D.G. Streets, Q.
Zhang, Y. Wang, S. Wu. (2010) Source attribution and interannual variability
ofArcticpollutioninspringconstrainedbyaircraft(ARCTAS,ARCPAC)and
satellite(AIRS)observationsofcarbonmonoxide,AtmosphericChemistryand
Physics10: 977-996,doi: 10.5194/acp-10-977-2010.
Fisher, J.A., D.J. Jacob, Q. Wang, R. Bahreini, C.C. Carouge, M.J. Cubison,
J.E. Dibb, T. Diehl, J.L. Jimenez, E.M. Leibensperger, Z. Lu, M.B.J. Mein-
ders, H.O.T. Pye, P.K. Quinn, S. Sharma, D.G. Streets, A. van Donkelaar, and
R.M.Yantosca. (2011)Sources,distribution,andacidityofsulfate-ammonium
aerosolintheArcticinwinter-spring,AtmosphericEnvironment,inpress,doi:
10.1016/j.atmosenv.2011.08.030.