Long−Range Transport of Asian Sulfate and Its Effects on the Canadian Sulfate Burden

Aaron van Donkelaar, Randall V. Martin – Dalhousie University W. Richard Leaitch, Anne Marie Macdonald – Environment Canada

Thomas W. Walker – University of TorontoDavid G. Streets, Qiang Zhang – Argonne National Laboratory

Edward Dunlea, Jose L. Jimenez – University of ColoradoJack E. Dibb – University of New Hampshire

Greg Huey, Rodney Weber – Georgia Institute of TechnologyMeinrat O. Andreae – Max Plank Institute for Chemistry

AGU Fall Meeting 2007December, 14th, 2007

INTEX−B

• Intercontinental Chemical Transport Experiment Phase B• NASA driven campaign• April-May 2006

• Sulfate enhancement in free troposphere

• Organic enhancement in boundary layer

• Sulfate mass scaled by 1.4 to compensate for size restrictions

Trans−Pacific sulfate observed at Whistler?

600

700

800

900

Alti

tude

[k

m]

Pressure

[hPa]

Aerosol Concentration [µg/m3]

0 3 6

H2O Concentration [g H2O/kg]

0 1 2 3

4

3

2

1

SO4=

Org

NH3

Sulfate contributes to East Asian AODModel (GEOS-Chem) MODIS MISR

MODISMISRAllDust ModelSO4

=

Model held at 2000 anthropogenic emissions

Fall AOD trend reflects SOx emissions

6.2 – 9.6% emission

growth per year

MODISMISRAllDust ModelSO4

=

Model held at 2000 anthropogenic emissions

Asian sulfate dominates INTEX−B sulfate

• Filter Pack 25% higher than unscaled Mist Chamber

• C130 and Cessna measurements scaled by 1.4

AircraftFull EmissionsNo East Asia ModelNo Anthro.

Significant growth to East Asian contribution

• 2.4-3.4x increase in simulated East Asian contribution since 1985

AircraftFull EmissionsNo East Asia ModelNo Anthro.

Long−range transport affects NA sulfate burden

• 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]

Long−range transport degrades surface air quality

• Mean surface conditions well correlated with simulated East Asian influence during April-May 2006

• Mean increase of 0.38 µg/m3 per +10% Asian influence

% Asian (simulated)

Mea

sure

d S

O4=

[µg/

m3]

Conclusions

• 6.2-9.6% annual mean increase in anthropogenic East Asian SOx emissions since 2000

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

• Anthropogenic East Asian sulfate degrades NA surface air quality