Long−Range Transport of Asian Sulphate to CanadaLong−Range Transport of Asian Sulphate to Canada

Aaron van Donkelaar, Randall V. Martin, Thomas Walker – Dalhousie University

W. Richard Leaitch, Anne Marie Macdonald – Environment Canada

David G. Streets, Qiang Zhang – Argonne National Laboratory

Edward Dunlea, Jose L. Jimenez – University of Colorado

Jack E. Dibb – University of New Hampshire

Greg Huey, Rodney Weber – Georgia Institute of Technology

Meinrat O. Andreae – Max Plank Institute for Chemistry

CAFC Meeting31 March 2008

Intercontinental Chemical Transport Experiment (INTEXIntercontinental Chemical Transport Experiment (INTEX−−B) B) April-May 2006April-May 2006

DC-8

SO4= (filters,

mist chamber)

C-130

SO4= (HR-ToF-AMS,

PILS)

Cessna

SO4= (Q-AMS)

King Air (May 1985)

SO4= (filters)

Whistler Summit

SO4= (MOUDI)

Trans−Pacific Sulphate Observed at Whistler?Trans−Pacific Sulphate Observed at Whistler?

Alti

tude

[k

m]

Mass Concentration [µg/m3]

0 3 6

H2O Concentration [g H2O/kg]

0 1 2 3

4

3

2

1

SO4=

Org

NH3

Average over April 22 - May 15 AM at Whistler (20 flights)Average over April 22 - May 15 AM at Whistler (20 flights)

0

1000

2000

3000

4000

5000

6000

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Number Cn (cm-3); Mass Cn (mg/m-3); Ozone (ppbv)

Alti

tude

(m

-MS

L)

Number >1umSulphateOrganicsNitrateOzone/100

0

1000

2000

3000

4000

5000

6000

0 500 1000 1500 2000 2500 3000

Number concentrations (cm-3)

Total >120 nm

Total >15 nm

Increasing Aerosol Size with AltitudeIncreasing Aerosol Size with Altitude

Richard Leaitch

Sulphate and Calcium at Whistler Summit (2182m)Sulphate and Calcium at Whistler Summit (2182m)

<1 mmy = 0.0008x + 0.0317

R2 = 5E-05

>3 mmy = 1.152x - 0.0181

R2 = 0.8589

1-3 mmy = 0.2102x + 0.0159

R2 = 0.3822

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0 0.2 0.4 0.6 0.8 1 1.2

Sulphate (mg/m3)

Cal

cium

(m g

/m3 )

> 3 microns

1-3 microns

<1 micron

Richard Leaitch

Simulated (GEOS-Chem) Sulphate TransportSimulated (GEOS-Chem) Sulphate Transport

Sulphate Major Component of East Asian AODSulphate Major Component of East Asian AOD

Model (GEOS-Chem) MODIS MISR

MODISMISRAllDust ModelSO4

=

Model held at 2000 anthropogenic emissions

GC Bias 12%MODIS 22% MISR

r=0.68r=0.60

Fall AOD Trend Reflects Increasing Asian SOFall AOD Trend Reflects Increasing Asian SO22 Emissions Emissions

Consistent with Subsequent Bottom-up EstimateConsistent with Subsequent Bottom-up Estimate

6.2 – 9.6% emission

growth per year

MODISMISRAllDust ModelSO4

=

Model held at 2000 anthropogenic emissions

Campaign Mean SOCampaign Mean SO44== in Free Trop Primarily Asian in Free Trop Primarily Asian

Lower Tropospheric Transport over Ocean, Increasing Altitude at NALower Tropospheric Transport over Ocean, Increasing Altitude at NA

Filter Pack (<4.5 um) higher than unscaled Mist Chamber (< 1um)

C-130 and Cessna measurements scaled by 1.4

60-70% of SO4= of

East Asian origin at 600 hPa

AircraftFull EmissionsNo East Asia ModelNo Anthro.

East Asian SOEast Asian SO44== Fraction Increased by 2.4x – 3.4x Since 1985 Fraction Increased by 2.4x – 3.4x Since 1985

AircraftFull EmissionsNo East Asia ModelNo Anthro.

C-130 (May 2006) King (May 1985)

Long−Range Transport Affects NA Sulfate BurdenLong−Range Transport Affects NA Sulfate Burden

• GEOS-Chem April-May 2006• Persistent East Asian

contribution at 4 km• Near Vancouver:

– 25-30% of surface sulfate of east Asian origin

– 40% of sulfate burden (1-5 km) of east Asian origin

Alti

tude

[k

m]

SO

4= a

t 2.0

km

Alti

tude

[k

m]

% A

sian

S

O4=

SO

4=

[µg/

m3]

ConclusionsConclusions

• Trend in East Asian AOD appears to reflect increasing SO2 emissions

• 2.4-3.4x increase in the relative contribution of East Asian sulfate since 1985

• Pacific basin may contain trends in aerosol-cloud feedbacks