Using CMAQ-AIM to Evaluate the Gas-Particle Partitioning Treatment in CMAQ Chris Nolte Atmospheric...
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Transcript of Using CMAQ-AIM to Evaluate the Gas-Particle Partitioning Treatment in CMAQ Chris Nolte Atmospheric...
Using CMAQ-AIM to Evaluate the Gas-Particle Partitioning Treatment in
CMAQ
Chris Nolte
Atmospheric Modeling Division
National Exposure Research Laboratory
October 19, 2004
Acknowledgements
Prakash Bhave
Robin Dennis
K. Max Zhang
Tony Wexler
Lucille Bender
Charles Chang
Outline
• Characteristics of the CMAQ and CMAQ-AIM aerosol modules
• Approach
• Results
• Conclusions & Future Work
Comparison between CMAQ and CMAQ-AIM
Feature CMAQ CMAQ-AIM
Size representationModal
(3 lognormal modes)
Sectional
(currently 9 sections)
Mass transfer to
fine PMInstantaneous
equilibriumDynamic
Mass transfer to coarse PM
None Dynamic
Thermodynamics ISORROPIA AIM
Comparison between CMAQ and CMAQ-AIM
(continued)
Feature CMAQ CMAQ-AIM
Equilibrium State Metastable Stable
Sea salt No Yes
N2O5 → HNO3 heterogeneous conversion
No No
Coagulation Yes No
Approach
Model to model comparison
• Continental US domain, 32 km grid cell size, 24 vertical layers, SAPRC 99 chemical mechanism
• Summer (Jun 24 – Jul 31, 2001) and winter (Dec 24 – Jan 31, 2002) modeling periods
Results: O3Average ozone concentrations are identical in the two models.
Results: O3Average ozone concentrations are identical in the two models.
Excellent agreement in average SO4 concentrations Results: SO4
Excellent agreement in average SO4 concentrations Results: SO4
O3 and SO4 Difference Plots(CMAQ-AIM minus CMAQ)
O3 and SO4 Difference Plots(CMAQ-AIM minus CMAQ)
Results: Total NO3
Results: Total NO3
TNO3 Difference Plots (CMAQ-AIM minus CMAQ)
Results: Fine NO3
Results: Fine NO3
Fine NO3 Difference Plots (CMAQ-AIM minus CMAQ)
Results: HNO3
Results: HNO3
HNO3 Difference Plots(CMAQ-AIM minus CMAQ)
Results: NH4
Results: NH4
NH4 Difference Plots(CMAQ-AIM minus CMAQ)
Conclusions• Initial comparisons of CMAQ and CMAQ-AIM show
good agreement.
• Differences in nitrate partitioning may be due to:(1) Equilibrium assumption vs. dynamic mass transfer(2) Different thermodynamics - activity coefficients
(3) Coarse mode sink for NO3
• Future work will involve trying to evaluate these differences independently(1) Run CMAQ-AIM without sea-salt emissions(2) Run CMAQ-AIM with ISORROPIA
The research presented here was performed under the Memorandum of Understanding between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Commerce’s National Oceanic and Atmospheric Administration (NOAA) and under agreement number DW13921549. Although it has been reviewed by EPA and NOAA and approved for publication, it does not necessarily reflect their policies or views.