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Comparing models of reactive nitrogen chemistry in Asia

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Comparing Models of NOx
Chemistry in Asia
Tracey Holloway, Columbia University
MICS-Asia Workshop 2001
Acknowledgements
•Hiram Levy II, NOAA GFDL
•Greg Carmichael, University of Iowa
•Markus Amann and TAP Project, IIASA
•Meredith Galanter, Larry Horowitz, Mahesh Phadnis
•Support from DoD, NASA, Princeton Univ., GFDL
Outline
• Model Overview
• Comparing with Observations
• Regional Lagrangian vs.
Global Eulerian
• ATMOS-N Results
ATMOS: Model Overview
•
•
•
•
Lagrangian, forward
1o x 1o resolution
NCEP winds (1990)
NCEP precipitation
• Vertical motion by
“puff splitting”
• Linear chemistry only,
non-interacting puffs
ATMOS-N Model Chemistry
Fossil Fuel, Biomass Burning, Biogenic
Fossil Fuel Emissions in Asia
kTon NO2/grid-yr
(IIASA, Van Ardenne)
Model vs. Observations, I
Annual Wet HNO3 Deposition (mg N/m2-yr)
Observations from Dentener
and Crutzen, 1994
Model vs. Observations, II
Annual Wet HNO3 Deposition (mg N/m2-yr)
Observations from
Fujita et al., 2000
Model vs. Aircraft Obs
OBS
GFDL GCTM
Feb.-Mar.
ATMOS
Sept.-Oct.
Tropical W. Pac.
Mid-lat. W. Pac.
GCTM: Model Overview
• Global, Eulerian
• 11 vertical layers,
variable resolution
~2.5o x 2.5o at midlatitutes
• GCM-generated
winds/precipitation,
“typical” year
• Off-line chemistry—same
scheme as ATMOS
Deposition Budgets in 2 Models
(kTon N/yr)
GCTM,
Asia FF
% Emission
ATMOS, Asia % Emission
FF
Fossil Fuel
Emissions
6209
Wet HNO3 Dep
3209
52%
1775
36%
Dry HNO3 Dep
1220
20%
1298
26%
Dry NOx Dep
459
7%
278
6%
Dry PAN Dep
146
2%
112
2%
Total NOy Dep
5034
81%
3463
70%
4964
GCTM vs. ATMOS-N
Global, Eulerian
Regional, Lagrangian
Annual Wet HNO3 Deposition (meq/m2-yr)
ATMOS-N vs. GCTM, at sites
ATMOS
OBS
GFDL GCTM
Both models too low in wet HNO3
deposition, but ATMOS lower.
ATMOS-N vs. GCTM, [HNO3]
Surface
Free Trop.
(~685 mb)
Summary: Model
Evaluation
• Overall correct “ballpark”
but…
• Wet HNO3 deposition too
low vs. obs
• Disagreement greatest at
“downwind” sites
• Upper Trop. NOx too low
in summer
• Although GCTM is also
too low in wet HNO3
deposition, ATMOS-N is
lower
• Not enough lateral
spreading
• Too much dry deposition
… All trace back to the
vertical transport in
ATMOS-N…
China Impacts
Winter
Summer
% wet HNO3 deposition due to fossil fuel emissions in China relative to all Asia
fossil fuel emissions
India Impacts
Winter
Summer
Japan Impacts
Winter
Summer
Transfer Matrix for HNO3
TO…
FROM…
TAIW
JAPAN
TAIW
80% 2%
JAPAN
1%
N KOR
S KOR
65% 1%
4%
3%
34% 7%
S KOR
12%
20%
63%
18%
46%
26%
18%
INDIA
1%
INDIA
2%
N KOR
CHINA
CHINA
1%
90%
6%
95%
Relative Nitrate Burden
Total= Total S +
Total NO3(meq/m2/yr)
% NO3-
Summary: Regional Transfer of HNO3
• Significant Transfer within east Asia, and from India to
west China
• China contributes 18% to total nitrate deposition (wet +
dry) in Japan, 46% to North Korea, 26% to South Korea
• Most exchange in winter, when winds are stronger,
precipitation less
• NOx much more localized due to shorter lifetime
• Nitrate contributes 30-50% of total acidification over much
of Japan, but less than 20% over much of east China.
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