1. Global 3-D Model Analysis of TRACE-P HCN and CH3CN Measurements
Qinbin Li, Daniel J. Jacob, Robert M. Yantosca
Harvard Atmospheric Chemistry Modeling Group
Hanwant B. Singh
NASA Ames Research Center
Makoto Koike
University of Tokyo
Glen W. Sachse
NASA-Langley Research Center

2. Atmospheric Budget of HCN (pre-TRACE-P)
Li et al. [2000]
Total atmospheric burden (Tg N)
0.50
Atmospheric lifetime (months)
Sources (Tg N yr-1)
Biomass burning
Sinks (Tg N yr-1)
Ocean uptake
Oxidation by OH
0.3
Photolysis
0.2×10-2
Reaction with O(1D)
0.3×10-3
Biomass burning emission ratio (relative to CO): 1.1%.

3. Vertical profiles in marine background atmosphere: Evidence for oceanic uptake of HCN and CH3CN
Background: CO < 120 ppbv, C2Cl4 < 10 pptv
Inferred saturation ratios: 0.84 for HCN, 0.80 for CH3CN

4. CH3CN-HCN Correlation in TRACE-P
Biomass
burning
“Shanghai plume”
(flight 13)
Biofuels (?)
Red: C2Cl4 > 11 pptv
Blue: C2Cl4 < 11 pptv

5. Use HCN/CO and CH3CN/CO ratios measured in Chinese pollution plumes to infer biofuel emission ratios
Flight #13
Assuming fresh fossil fuel+biofuel emissions. CO: biofuel/(fossil fuel+biofuel) ~42% for Shanghai + Jiangsu + Zhejiang [D. Streets, 2001] . Hence HCN/CO biofuel emission ratio ~ 0.40%.

6. Correlations: > 2 km Emission ratios relative to CO (% molar):
biomass burning
Biofuel
HCN
0.14
0.34
CH3CN
0.12
0.22
Asian CO emissions
(March 2001):
14 Tg fossil fuel
13 Tg biofuel
59 Tg biomass burning

7. Simulated vs. observed vertical profiles
Red: observation
Blue: model
Green: biomass burning
Pink: biofuel
Yellow (CO only): fossil fuel

8. Simulated vs. observed frequency distributions
Red: observation
Blue: model

9. Simulated vs. observed HCN columns
Moshiri (44°N, 142°E)
Rikubetsu (45°N, 144°E)
Tsukuba (36°N, 140°E)
Red: observation
Blue: model

10. Atmospheric Budgets for HCN and CH3CN
Li et al. [2000] in red
HCN
CH3CN
Atmospheric burden (Tg N)
0.42 (0.50)
0.20
Atmospheric lifetime (month)
5.0 ( )
3.2
Sources (Tg N yr-1)
Biomass burning
0.51 ( )
0.43
Biofuel
0.48
0.31
Sinks (Tg N yr-1)
Ocean uptake
0.74 ( )
0.52
Oxidation by OH
0.25 (0.3)
0.22