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