Impact of Changes in Future Anthropogenic Aerosol Emissions on Northern Hemispheric Regional Air...

8/3/2019 Impact of Changes in Future Anthropogenic Aerosol Emissions on Northern Hemispheric Regional Air Quality and Cli

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AbstractAnthropogenic* aerosols play important roles in

climate change, air quality, and human health

and visibility. To better understand the impact of

changes in future anthropogenic emissions, we

analyzed output from the NASA Goddard Chemistry

Aerosol Radiation Transport(GOCART) Global

Model for present (year 2001) and future (years

2030 and 2050) emission scenarios with a focus

on northern hemispheric air quality and climate.

GOCART uses assimilated meteorological felds

from the NASA Goddard Earth Observing System

Data Assimilation System (GEOS DAS version 4).

In this study, which is part of a comprehensive

project coordinated by the United Nations Task

Force on Hemispheric Transport of Air Pollution

(HTAP), anthropogenic sulfur aerosols, black

carbon (BC), and particulate organic matter

(POM) were analyzed for surface concentration,

column load and deposition over time, source

attribution, source-receptor relationships, and

Relative Annual Intercontinental Response(RAIR). The analysis used fve tagged regions,

including four major anthropogenic source (and

also receptor) regions of East Asia, Europe, North

America, and South Asia, and one climatically

sensitive receptor region of the Arctic. This

study reveals a sensitivity of North American

air quality and climate to Asian anthropogenic

emissions, and an Arctic vulnerability to Asian

and European emissions. Our results suggest that

intercontinental transport is a critical element to

be considered in the development of emissioncontrol strategies for northern hemispheric air

quality and climate.

IntroductionAerosols, also referred to as particulate matter (PM),are liquid or solid particles suspended in the air thataffect climate, air quality, and human health andvisibility20. Atmospheric aerosols originate from bothanthropogenic (such as fossil fuel combustion, oildrilling, and agriculture) and natural (such as desert

Impact of Changes in Future AnthropogenicAerosol Emissions on Northern HemisphericRegional Air Quality and ClimateMaureen Lei1,3, Elizabeth Duval2, and Mian Chin4

Student1,Teacher2: Montgomery Blair High School, 51 East Boulevard, Silver Spring, MD, 20901Intern3, Mentor/Professor4: NASA Goddard Space Flight Center, 8800 Greenbelt Rd., Greenbelt,Maryland 20771

ACCELERATED ARTICLE

storms, volcanoes, vegetation, and wildres) sources Anthropogenic activities have become a signicansource of atmospheric aerosols, including sulfate

nitrate, black carbon (BC), and particulate organicmatter (POM), among others. Aerosols generatedby anthropogenic emissions consist mostly of ne-mode particles (less than 2.5 m in diameter) that canbe harmful to human health12. The principal aerosocomponents are sulfate and POM, which reect solarradiation to space and therefore cool the atmosphere5

BC is only a minor contributor to aerosol mass butis of great climatic concern as an absorber of solarradiation both in the atmosphere and after depositionto snow, thus contributing to atmospheric warmingand the melting of snow and ice16.

Anthropogenic aerosols have relatively shoatmospheric lifetimes (several days). In spite of theirshort lifetimes, aerosols originating in one region cantravel long distances to affect the environments ofdownwind regions5, demonstrating the hemispheric

to global scale of aerosol inuence. In the northern

hemisphere, specic source-receptor relationshipshave been identied. Model experiments suggest theregular outow of Asian air pollution over the Pacicto North America through conveyer belt activity21

This mechanism has been conrmed through th Transport and Chemical Evolution over the Paci(TRACE-P) aircraft mission11. Further, Asia has been

shown to be inuential over most of the northernhemisphere, except for in the North Atlantic andthe tropics4. Intercontinental transport from Europehas also been studied. Europe lacks mechanismsto effectively transport aerosols across the AtlanticOcean17. Instead, European outow tends to traveNorth to the Arctic, contributing to Arctic haze15.

European emissions, however, are capable ofreaching other northern hemispheric regions by

traveling eastward across Asia and the Pacic toreach North America. Because these aerosols tendto mix with Asian emissions, they are difcult todetect4. Anthropogenic emissions in the industrialperiod greatly increased the amount of aerosols in

*caused or produced by humans


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Maureen Lei, Elizabeth Duval, and Mian Chin Page 2 of 8

the northern hemisphere13. As a result of economicdevelopment, and emission control policies andtechnologies, anthropogenic emissions from the major

northern hemispheric source regions will continueto change in the coming decades, as projected by

the future emission scenarios developed for the 5thIntergovernmental Panel on Climate Change (IPCC)assessment report14. Even though local and regionalemissions are primarily responsible for pollution,hemispheric transport of air pollution (HTAP) canintensify air quality issues caused by local and regionalemissions19. To understand the impact of changes

in future anthropogenic emissions, we analyzedanthropogenic northern hemispheric emissions,intercontinental transport, and source-receptorrelationships in present(year 2001) and future (years

2030 and 2050) emission scenarios. Intercontinentaltransport was studied among ve tagged regions: East Asia, Europe, North America, South Asia, and theArctic (Fig. 1) using the Goddard Chemistry Aerosol

Radiation Transport (GOCART) Global Model. TheArctic is strictly a receptor region. Its air quality can beinuenced by anthropogenic emissions from outsideregions, but it produces few anthropogenic emissionsof its own to inuence outside air quality. The otherfour regions are source and receptor regions.

In this paper, we present the model and emissionscenarios, aerosol concentration behavior overtime, source attribution of aerosol species, source-

receptor relationships amongst tagged regions, andRelative Annual Intercontinental Response (RAIR).Our results show that North American surfaceconcentration and column load, which are relevant toair quality and climate change respectively, are sensitiveto Asian anthropogenic emissions; and Arctic columnload is sensitive to Asian and European emissions. These ndings demonstrate the importance of

intercontinental transport in air quality and climate.The implications of these ndings on future air quality,climate, human health, and policy are discussed.

salt, and POM1,2,3,4,7,8. The model uses assimilated

meteorological elds from the NASA Goddard EarthObserving System Data Assimilation System with ahorizontal resolution of 2 latitude by 2.5 longitudeand 30 vertical layers. Processes included are emissionsfrom anthropogenic, biomass burning and naturasources, transport, chemistry, and dry and wet removalUsing GOCART, we examined three anthropogenicemission scenarios specied by HTAP: SR1 (2001)

FE1 (2030), and FE2 (2050). Figure 2 showschanges in global anthropogenic emissions. The2001 simulation uses present-day emissions, whereas2030 uses Representative Concentration Pathway(RCP) 8.5-like emissions (high non-anthropogenicgreenhouse gas emissions, low methane) and 2050uses RCP2.6-like emissions (low nonanthropogenicgreenhouse gas emissions, low methane)14. The year2030 and year 2050 simulations are driven by 2001

meteorological elds. Both RCP emission scenarioswere assigned by the United Nations Task Force on the

Hemispheric Transport of Air Pollutants. Table 1 liststhe anthropogenic emissions of SO2, BC, and POM in2001, 2030, and 2050 in the four major source regionsof North America, Europe, East Asia, and South AsiaEast Asian and South Asian anthropogenic emissionsincrease by 5% and 47%, respectively, from 2001 to

2030, while other regions decrease (Table 1, 2001 and2030). From 2030 to 2050, anthropogenic emissionsdecrease in all four tagged regions (Table 1, 2030and 2050). With each scenario, ve global modeexperiments were conducted: one with all emissions

Figure 1.Source and receptor regions designated in this

study. The map shows the tagged regions that were used in the

GOCART Global Model runs. EA (East Asia), EU (Europe),NA (North America), and SA (South Asia), each boxed and

highlighted in color, are all source and receptor regions. AR

(Arctic, latitudes > 66.5N) is only a receptor region.

Materials and MethodsGOCART global model experiments were carriedout to address source attribution and source-receptor

relationships in present and future emission scenariosfor sulfate, BC, and POM. GOCART is used tosimulate major aerosol species and their precursorsin the troposphere including sulfur, dust, BC, sea


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(including natural and anthropogenic), and the otherfour with anthropogenic emissions reduced by 20%in each of the major source regions. To quantify theintercontinental inuence of changes in anthropogenicemissions, we examine source attribution, source-receptor relationships, and RAIR among these regions.

For our analysis, we calculated source attribution values, which represent the percent of aerosols in a regionthat can be attributed to anthropogenic emissions

from a single source region. They are calculated bynding the ratio between the amount of aerosol fromanthropogenic emissions in a specied source regionand the total amount of aerosol in a specied receptorregion (A/T, where A = aerosols attributed to a

specied source region and T = total aerosol in receptorregion). Source-receptor relationship values were alsocalculated. They represent the percent reduction inconcentrations or depositions of a receptor regionin response to a 20% reduction in anthropogenicemissions of a source region19. Source-receptor

relationship values are calculated as follows: (OR)/O, where O = original receptor region concentration,and R = receptor region concentration after 20%

reduction in source regions anthropogenic emissions. They describe the sensitivity of concentrations ordepositions of a receptor to changes in emissions froma source. RAIR is the sum of changes in the annual,regionally averaged concentration in a region due to a20% decrease in emissions in the three other regions,divided by the sum of changes in concentration within

Figure 2. Anthropogenic emission changes over time. Thesum of emissions of anthropogenic aerosol (sulfur species, or

BC, or POM) from all source regions in a year is representedby a bar. 2001, 2030, and 2050 are represented by the black,

light gray, and dark gray bars, respectively. TgM=TgS forsulfur species, TgC for BC and POM.

a region due to a 20% decrease in emissions in allfour regions19. For example, RAIR for North Americais calculated as follows: N/F, where N = changes

in North American aerosol in response to a 20%reduction in East Asian, European, and South Asian

anthropogenic emissions and T = changes in North American aerosol in response to 20% reductions inanthropogenic emissions of all four source regionsRAIR ranges from 0%, indicating no intercontinentalinuence, to 100%, indicating complete dominationby intercontinental sources. It is a measure of howmuch a region may benet from emission reductions

in other regions if reductions occur on the northernhemispheric scale.

Table 1. Anthropogenic emissions in source regions for

years 2001, 2030, and 2050. SO2, BC, and POM emissionsused in GOCART Global Model runs in 2001, 2030, and 2050

emission scenario are shown in the top, middle and bottomsub-tables, respectively. SO2 instead of SO4 emissions were

used because most anthropogenic SO4 comes from convertedSO2. EA: East Asia. EU: Europe. NA: North America. SA:

South Asia.

ResultsNorthern hemispheric aerosols selectively decreasein future emission scenarios: With changes in

anthropogenic emissions from 2001 to 2050, therewere paralleled changes in total northern hemisphericpollutant concentrations and depositions. Increasesand decreases in surface concentrations, columnloads, and depositions (Fig. 3) generally matchedincreases and decreases in regional anthropogenic

emissions (Table 1). North American and Europeananthropogenic emissions steadily decreased, as shownin Table 1. With these decreases, we see decreases insurface concentrations, column loads, and depositions


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in both regions (Fig. 3). North America exhibited the most dramatic reductions of all sulfate surface concentrationsover the East Coast (Fig. 3, top row). They fall from a peak of 2.0-3.0 gS/m3 in 2001 (Fig. 3, top row, left map) toa peak 0.30-0.40 gS/m3 (Fig. 3, top row, right map) in 2050. North American East Coast BC column load levels

drop as well, but over a signicantly smaller range (Fig. 3, middle row). The highest 2001 levels registered at 0.70-1.0mgC/m2 (Fig. 3, middle row, left map) and the highest 2050 levels registered at 0.30-0.40mgC/m2 (Fig. 3, middle

row, right map). There are also reductions in sulfate deposition over the same region (Fig. 3, bottom row). In 20011.0-2.0 mgS/m2/day at most are deposited over the North American East Coast (Fig. 3, bottom row, left map)but in 2050, 0.20-0.30 mgS/m2/day at most are deposited (Fig. 3, bottom row, right map). Similarly, the changesin amount of aerosols in East Asia and South Asia matched changes in regional anthropogenic emissions. EasAsian and South Asian distributions increase from 2001 to 2030 and decrease from 2030 to 2050 (Fig. 3), consistentwith the uctuation of emission changes (Table 1). In terms of absolute amount, East Asia is consistently hometo the highest amounts of aerosols out of all the tagged regions. In 2001 and 2030, East Asias sulfate surface

concentrations are as high as 5.0-7.0 gS/m3, while the sulfate surface concentrations of other tagged regionspeak at 3.0-5.0 gS/m3 (Fig. 3, top row, left and middle map). By 2050, East Asias sulfate surface concentrationspeak at 1.0-2.0 gS/m3, while those of other tagged regions always fall below 0.50 gS/m3 (Fig. 3, top row, rightmap). Also, East Asias 2001 and 2030 BC column loads are as high as 3.0-5.0 mgC/m2, compared to the less than

1.0 mgC/m2 column loads of the rest of the tagged regions (Fig. 3, middle row, left and middle map). Its 2050BC column loads are as high as 1.0-2.0 mgC/m2, outdoing the BC column loads of the rest of the tagged regionswhich largely register below 1.0 mgC/m2 (Fig. 3, middle row, right map). Lastly, East Asian sulfate depositions in2001 and 2030 register as high as 3.0-5.0 mgS/m2/day, outdoing the less than 2.0 mgS/m2/day sulfate depositions

in the rest of the world (Fig. 3, bottom row, left and middle map). In 2050, sulfate is deposited over East Asia inquantities as high as 1.0-2.0 mgS/m2/day; the most deposited over other regions is 0.50 mgS/m2/day (Fig. 3,bottom row, right map).Intercontinentaltransport exerts inuencein regional air quality andclimate in future emission

scenarios: In evaluatingthe source attributionof aerosols in all source

regions, it is evident thatlocal emissions are themost signicant individualcontributor to localconcentrations (Figs. 4, 5,and 6). In most cases, theamount of aerosols in aregion is controlled more

by local anthropogenicemissions thanoutside anthropogenicemissions. The impact ofintercontinental transportfrom outside tagged regions, however, is stillnoteworthy. North America is the most signicantcontributor to its own air quality. Its surfaceconcentration from 2001 to 2050 is dominated by

its own anthropogenic emissions for all aerosol

Figure 3. Northern hemispheric anthropogenic aerosol distributions in2001, 2030, and 2050. Sulfate surface concentration, BC column load andsulfate deposition in tagged areas (North America: 125W-60W, 15N-55NEurope: 10W-50E, 25N-65N, South Asia: 50E-95E, 5N-35N, East Asia95E-160E, 15N-50N, and Arctic: 180W-180E, 66.5N-90N) are shown in themaps in the top, middle and bottom row, respectively. In each row, the leftmiddle, and right map show distributions in 2001, 2030, and 2050, respectivelyColor changes in tagged regions indicate changes in aerosol amounts. Thecolor key assigns a range of aerosol concentrations to a specic color.


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species (Fig. 4). At their highest, aerosols from North American anthropogenic emissions constitute nearly90% of North American BC (Fig. 4, B). East Asia

is the second most signicant contributor to NorthAmerican pollutants, but its anthropogenic emissions

account for less than 20% of North American surfaceconcentration (Fig. 4, D and E). By 2050, however,there is a decrease in how much of North Americassurface concentration can be attributed to its ownanthropogenic emissions (Fig. 4, G, H, and I). The mostextreme example is the decrease in sulfate attributions.In 2001, North America controls nearly 80% of its

own sulfate surface concentrations (Fig. 4, A). By2050, North American anthropogenic emissions willbe responsible for less than 40% of the regions ownsulfate pollution (Fig. 4, G). However, anthropogenic

emissions from other source regions also have verylittle impact. East Asian anthropogenic emissions,again the second most signicant contributor, areresponsible for at most 5% of North American sulfate

(Fig. 4, G).North American column load, which is relevant

to climate change, is sensitive to intercontinentaltransport (Fig. 5). In 2030, North Americas BCcolumn load is atypically sensitive to anthropogenicSouth Asian and East Asian emissions (Fig. 5, E).

For all of 2030, anthropogenic North American BC

emissions are completely overtaken by at leastone other region in determining North AmericanBC column loads. Anthropogenic East Asian BC

emissions are responsible for a greater percentageof North American BC column loads than

anthropogenic North American BC emissions forthe entire year, and anthropogenic South Asian BCemissions are responsible for a greater percentagethan anthropogenic North American BC emissions inthe spring and fall months (Fig. 5, E). North Americasresponse to anthropogenic East Asian and South AsianBC emissions in the 2001 and 2050 emission scenarios

is not as dramatic. However, East Asia and South Asiaare consistently the second and third most signicantcontributors to North American column loads (Fig. 5B and H). Although total BC column loads are the

most dramatic example of North America developingsensitivity to outside sources, sulfate (Fig. 5, A, D, andG) and POM (Fig. 5, C, F and I) column loads alsodemonstrate vulnerability to anthropogenic emissions

from other tagged regions. From 2001 to 2030, North American control of its own sulfate column loadrops from a peak of 75% (Fig. 5, A) to a peak of40% (Fig. 5, D). East Asian inuence also increasesfrom 2001 to 2030, becoming more inuentialrelative to North American emissions. In 2030

anthropogenic East Asian sulfate emissions are theFigure 4. North American surface

concentration source attribution inyears 2001, 2030, and 2050. Yaxis

in each graph: percent of North American surface concentrat

attributed to anthropogenic emissionsfrom four source regions (EA: East Asia, EU: Europe, NA: Nor

America, SA: South Asia). Each sourceregion is represented by a colored line

X-axis in each graph: months of the

year. The left (A, B, C), middle (D, EF), and right (G, H, I) columns are fosource attribution in years 2001, 2030and 2050, respectively. The top (A, D

G), middle (B, E, H), and bottom (CF, I) rows are for source attribution of

sulfate, BC, and POM, respectively.



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second-most signicant anthropogenic contributorto North American sulfate column loads. For therst three months of 2030 in particular, East Asian

contributions trail North American contributions,consistently falling less than 5% below anthropogenicNorth American contributions (Fig. 5, D). North American POM column loads are less sensitive tooutside anthropogenic sources, but anthropogenicsources in general are relatively minor contributors.

The sum of POM column load attributed to outsideanthropogenic sources is less than 20% of total POM

column load in 2001 and 2050 (Fig. 5, C and I). In2030, the inuence of intercontinental transport peaks(Fig. 5, F). For all of 2030, less than 20% of POMcolumn load can be attributed to North Americananthropogenic emissions. However, at least 5% ofPOM column load can be attributed to East Asia andSouth Asia. Most notably, in October of 2030, South Asian and North American contributions are equal(Fig. 5, F).

DiscussionOur analysis reveals signicant decreases in surface

concentrations, column loads, and depositions across the northern hemisphere in future emission scenarios (Fig3). This nding suggests that intercontinental coordination of emission reductions could lead to across the boarddecreases in amounts of aerosols. Because of the contributions of local emissions and intercontinental transport, abalance of local and hemispheric regulation may be necessary. Furthermore, a targeted approach may prove usefuin controlling northern hemispheric air quality in the future. In particular, regulation of North American climate(particularly for BC column loads) may require coordination between North American and East Asian governments

This argument is supported by several ndings of this study: Source attribution between the two regions show

Figure 5. (Top) North American column load sourceattribution in years 2001, 2030, and 2050. Y-axis in eachgraph: percent of North American column load attributed toanthropogenic emissions from four source regions (EA: EastAsia, EU: Europe, NA: North America, SA: South Asia). Eachsource region is represented by a colored line. X-axis in eachgraph: months of the year. The left (A, B, C), middle (D, E, F),

and right (G, H, I) columns are for source attribution in years2001, 2030, and 2050, respectively. The top (A, D, G), middle(B, E, H), and bottom (C, F, I) rows are for source attribution ofsulfate, BC, and POM, respectively.

Figure 6. (Bottom) Arctic column load source attributionin years 2001, 2030, and 2050. Y-axis in each graph: percent ofArctic column load attributed to anthropogenic emissions fromfour source regions (EA: East Asia, EU: Europe, NA: NorthAmerica, SA: South Asia). Each source region is represented bya colored line. X-axis in each graph: months of the year. The left(A, B, C), middle (D, E, F), and right (G, H, I) columns are forsource attribution in years 2001, 2030, and 2050, respectively.The top (A, D, G), middle (B, E, H), and bottom (C, F, I) rows

are for source attribution of sulfate, BC, and POM, respectively.



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a signicant portion of North American aerosols

coming from anthropogenic East Asian emissions(Figs. 4 and 5), RAIR calculations reveal high sensitivityof North American air quality to intercontinentaltransport (Table 3, Appendix), and source-receptor

calculations demonstrate sensitivity of North American air quality to anthropogenic East Asianemissions in particular (Table 2, Appendix). Althoughuctuations in anthropogenic East Asian emissions

will not guarantee proportional uctuations in North American air quality, other outcomes are unlikelybecause of the conrmed path of air pollutants from Asia to North America11. Because East Asia is in acontinual state of economic development, furtheructuations in its anthropogenic emissions are almostguaranteed. Therefore, North America will do itself

a disservice if it neglects to negotiate anthropogenicemission regulations with East Asia; it may end

up having little control over its own air quality andclimate, and the health of its citizenry. In addition toNorth America, Arctic climate may also benet fromspecial attention.

Concerns regarding the Arctic are not directedtowards direct impacts on human health, but rather,the chain reaction on global climate that may be setoff by changes in Arctic climate. Although a uniform,

northern hemispheric reduction in anthropogenicemissions will likely reduce intercontinental transportto the Arctic, reductions in anthropogenic EastAsian and European emissions may prove especiallybenecial, especially because of the conrmednorthward path taken by European emissions18. We conducted a novel investigation to gauge theconsequences of changes in future anthropogenicaerosol emissions on northern hemispheric air quality

and climate. Different regions displayed varyingdegrees of sensitivity to intercontinental transport. In

particular, North America and the Arctic (judged bysource attribution, source-receptor relationships, andRAIR) demonstrate vulnerability to intercontinentaltransport. North American air quality shows sensitivityto anthropogenic East Asian emissions. Signicantportions of North American aerosols have been

attributed to anthropogenic East Asian emissions(Figs. 4 and 5), and source receptor calculations forNorth America demonstrated heightened sensitivity tochanges in anthropogenic East Asian emissions (Table

2, Appendix). Further, RAIR calculations for North

America demonstrated a high level of dependence oflocal air quality on all intercontinental sources (Table3, Appendix). Arctic climate was also revealed tobe sensitive to outside sources. In particular, Arctic

climate is inuenced by anthropogenic East Asian andEuropean emissions (Fig. 6). These results suggest that the effective way t

control local climate, especially for North America

and the Arctic, is to coordinate emission reductionson a larger scale, whether global or hemispheric. Forthese two regions in particular, targeted reductionsin emissions of key source regions and regulationof intercontinental transport may prove necessaryto control local air quality. Previous observatory andmodeling studies5,11,18,21 for the present day have reached

similar conclusions, including long range transport ofpollutants from Asia to North America11,21, from Asia

to the Arctic17, and from Europe to the Arctic5. The trends in intercontinental transport in ou

study were consistent with the trends identied in paststudies. Our study, however, provides a projection intothe future. To further solidify the results of this moderun, the same emission scenarios will need to be testedin other models. Multiple model runs with futureemissions scenarios will prove useful in planning ahead

for policy recommendations to manage the impacts offuture anthropogenic emission uctuation.

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2001 EmissionsSource: EA EU NA SA

Species

SO2 (mgS/m2/year) 597.49 742.24 358.51 277.55

BC (mgC/m2/year) 71.02 33.30 17.03 40.93POM (mgC/m2/year) 99.48 37.55 26.26 104.54

2030 Emissions

Source: EA EU NA SASpecies

SO2 (mgS/m2/year) 638.57 362.07 147.74 443.81

BC (mgC/m2/year) 74.55 13.96 6.33 50.52POM (mgC/m2/year) 89.54 14.06 17.35 127.26

2050 EmissionsSource: EA EU NA SA

SpeciesSO2 (mgS/m

2/year) 90.41 75.09 18.84 143.33BC (mgC/m2/year) 20.68 7.82 6.15 24.83

POM (mgC/m2/year) 62.74 25.67 21.54 80.20

2030 RAIR

Receptor: EA EU NA SA

Surface Concentration Response (%)

SO4 7.12 9.01 16.62 11.27

BC 2.65 10.75 21.56 7.79

POM 4.72 13.19 10.46 4.36

Column Load Response (%)

SO4 18.67 26.69 45.01 16.22

BC 16.61 54.79 71.56 15.74

POM 26.35 64.07 56.25 8.36

Deposition Response (%)

SO4 9.27 7.51 8.86 18.53

BC 7.45 8.79 18.98 16.78

POM 9.52 8.65 14.38 9.10

2001 RAIRReceptor: EA EU NA SA


SO4 10.00 7.11 10.20 22.25

BC 3.16 5.30 9.62 11.67

POM 4.13 5.68 7.82 6.68


SO4 23.29 20.35 27.74 32.89

BC 17.33 34.12 47.10 22.72

POM 22.58 39.43 45.62 12.89


SO4 9.27 9.52 8.86 18.53

BC 7.45 8.79 18.98 16.78

POM 9.52 8.65 14.38 9.10

2050 RAIRReceptor: EA EU NA SA


SO4 8.32 6.22 14.94 5.05

BC 4.85 9.24 8.83 5.51

POM 4.92 6.18 6.52 5.68


SO4 26.25 20.55 49.40 8.17

BC 26.85 48.99 48.42 11.64

POM 26.11 41.27 41.61 11.19


SO4 11.74 5.60 14.88 4.35

BC 12.31 14.30 18.04 8.30

POM 11.30 9.41 12.24 7.74

Table 1. Anthropogenic emissions in source regions for years 2001, 2030, and 2050. SO2, BC, and POM

emissions used in GOCART Global Model runs in 2001, 2030, and 2050 emission scenario are shown in the top,

middle and bottom sub-tables, respectively. SO2instead ofSO4 emissions were used because most

anthropogenic SO4comes from converted SO2. EA: East Asia. EU: Europe. NA: North America. SA: South

Asia.!

Table 3. Relative Annual Intercontinental Response (RAIR) in 2001, 2030, and 2050. Each sub-table shows RAIR

for surface concentration, column load, and deposition for four tagged regions in 2001, 2030, and 2050, respectively.

Each number represents the percent of concentrations or depositions of an aerosol (specified on the left of each sub-table)

influenced by intercontinental sources (specified on the top of each sub-table). For example, North American BC

column load (boxed in red) is 71.56% dependent on intercontinental sources. EA: East Asia. EU: Europe. NA: North

America. SA: South Asia. AR: Arctic.

!

APPENDIX


10/10

!

2001 Deposition Source-Receptor

Source: EA EU NA SA

Receptor

EA (% reduction)

SO4 11.38 0.55 0.11 0.50

BC 15.27 0.27 0.09 0.87

POM 7.62 0.08 0.03 0.69

EU (% reduction)

SO4 0.24 13 .27 0 .72 0. 12

BC 0.59 15.53 0.62 0.29POM 0.22 7.09 0.29 0.17

NA (% reduction)

SO4 0.66 0 .60 13 .95 0. 10

BC 1.79 0.55 12.37 0.56

POM 0.35 0.10 3.91 0.21

SA (% reduction)

SO4 1.33 1.48 0.14 12.95

BC 1.68 0.67 0.11 12.22

POM 0.61 0.12 0.03 7.60

2001 Column Load Source-Receptor

Source: EA EU NA SA

Receptor

EA (% reduction)

SO4 8.92 1.45 0.39 0.86

BC 12.36 0.53 0.23 1.83

POM 5.60 0.17 0.10 1.36

EU (% reduction)

SO4 0.85 10 .90 1. 59 0.3 5

BC 2.19 9.88 1.33 1.60POM 0.83 3.79 0.58 1.06

NA (% reduction)

SO4 1.77 1.16 8.82 0.46

BC 3.74 0.65 7.08 1.91

POM 1.08 0.16 2.67 1.01

SA (% reduction)

SO4 1.17 2.64 0.33 8.46

BC 1.83 0 .94 0.23 10.21

POM 0.67 0.22 0.07 6.51

2001 Surface Concentration Source-Receptor

Source: EA EU NA SA

Receptor

EA (% reduction)

SO4 11.02 0.78 0.14 0.31

BC 17.06 0.19 0.05 0.31

POM 9.85 0.08 0.03 0.32

EU (% reduction)

SO4 0. 25 13 .62 0.65 0. 14

BC 0.35 16.65 0.33 0.25POM 0.16 8.08 0.18 0.15

NA (% reduction)

SO4 0. 78 0 .65 13.4 7 0. 10

BC 1.03 0.30 14.93 0.26

POM 0.26 0.06 5.18 0.12

SA (% reduction)

SO4 1.25 2.02 0.21 12.15

BC 1.10 0.60 0.08 13.51

POM 0.47 0.12 0.02 8.68

A D G


Source: EA EU NA SA

Receptor

EA (% reduction)

SO4 11.67 0.23 0.03 0.80

BC 15.47 0.11 0.03 1.05

POM 7.10 0.03 0.02 0.87EU (% reduction)

SO4 0.44 12.72 0.44 0.33

BC 1.20 12.00 0.44 0.70

POM 0.26 3.32 0.25 0.26

NA (% reduction)

SO4 1.30 0.46 11.83 0.30

BC 3.11 0.36 7.61 1.17

POM 0.34 0.04 2.77 0.27

SA (% reduction)

SO4 1.06 0.51 0.04 14.83

BC 1.56 0.24 0.04 13.52

POM 0.51 0.04 0.02 8.67


Source: EA EU NA SA

Receptor

EA (% reduction)

SO4 11.46 0.34 0.05 0.50

BC 17.25 0.07 0.02 0.38

POM 9.32 0.03 0.02 0.41EU (% reduction)

SO4 0.46 12.60 0.40 0.39

BC 0.74 13.52 0.25 0.64

POM 0.19 3.94 0.16 0.24

NA (% reduction)

SO4 1.51 0.49 11.48 0.29

BC 2.06 0.23 10.54 0.61

POM 0.25 0.03 3.76 0.16

SA (% reduction)

SO4 1.03 0.72 0.06 14.26

BC 1.01 0.21 0.03 14.71

POM 0.39 0.04 0.01 9.77


Source: EA EU NA SA

Receptor

EA (% reduction)

SO4 9 .5 4 0. 63 0 .1 4 1. 42

BC 12.64 0.21 0.08 2.23

POM 5.15 0.06 0.07 1.71EU (% reduction)

SO4 1 .4 2 8. 78 0 .8 9 0. 88

BC 3.37 5.79 0.72 2.93

POM 0.86 1.56 0.44 1.48

NA (% reduction)

SO4 2 .7 0 0. 69 5 .4 5 1. 07

BC 5.01 0.33 3.33 3.05

POM 1.01 0.06 1.85 1.30

SA (% reduction)

SO4 1 .0 8 1. 05 0 .1 0 11. 49

BC 1.77 0.34 0.08 11.72

POM 0.57 0.07 0.05 7.55

B E H


Source: EA EU NA SA

Receptor

EA (% reduction)SO4 6.12 0.14 0.01 0.40

BC 13.15 0.11 0.05 0.51

POM 7.65 0.06 0.03 0.30

EU (% reduction)

SO4 0.13 9.33 0.13 0.37

BC 0.32 11.50 0.37 0.48

POM 0.11 6.36 0.17 0.13

NA (% reduction)

SO4 0.45 0.23 5.27 0.24

BC 0.64 0 .14 11.57 0.33

POM 0.17 0.05 4.50 0.10

SA (% reduction)

SO4 0.33 0.34 0.02 13.04

BC 0.48 0.20 0.04 12.41

POM 0.34 0.10 0.02 7.53


Source: EA EU NA SA

Receptor

EA (% reduction)SO4 3 .4 2 0 .2 3 0 .0 3 0 .9 5

BC 7.35 0.24 0.17 2.29

POM 4.03 0.13 0.09 1.20

EU (% reduction)

SO4 0 .3 0 4 .1 7 0 .2 1 0 .5 6

BC 1.41 4.81 1.06 2.15

POM 0.58 2.85 0.52 0.90

NA (% reduction)

SO4 0 .5 1 0 .2 1 1 .2 9 0 .5 7

BC 1.93 0.25 4.53 2.07

POM 0.72 0.11 2.33 0.83

SA (% reduction)

SO4 0 .2 8 0 .4 0 0 .0 2 7 .8 9

BC 0.79 0.30 0.12 9.25

POM 0.47 0.16 0.07 5.54


Source: EA EU NA SA

Receptor

EA (% reduction)SO4 5.63 0.09 0.01 0.64

BC 10.48 0.14 0.07 1.26

POM 5.66 0.07 0.03 0.62

EU (% reduction)

SO4 0.12 9.93 0.14 0.33

BC 0.50 9.98 0.65 0.52

POM 0.16 5.50 0.27 0.15

NA (% reduction)

SO4 0.37 0.22 4.84 0.25

BC 1.04 0.24 8.92 0.69

POM 0.23 0.07 3.36 0.17

SA (% reduction)

SO4 0 .3 6 0 .2 5 0 .0 1 1 3. 50

BC 0.74 0.22 0.06 11.26

POM 0.43 0.09 0.03 6.53

C F I

Table 2. Source-receptor relationships among tagged regions in 2001, 2030, and 2050. Each number in this table

represents the percent reduction in the receptor region (specified on the left of each sub-table) to a 20% reduction in

emissions from the source (specified on the top of each sub-table). For example, East Asian sulfate surface

concentration decreases 11.02% in response to a 20% decrease in its own anthropogenic emissions (A, boxed in red).

The sub-tables in the left (A, B, C), central (D, E, F), and right (G, H, I) columns show source-receptor relationships in

year 2001, 2030 and 2050, respectively. The sub-tables in the top (A, D, G), middle (B, E, H), and bottom (C, F, I)

rows show source-receptor relationships for surface concentration, column load, and deposition, respectively. EA: East

Asia. EU: Europe. NA: North America. SA: South Asia.!

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