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Helmut Roth, Weimin Jiang, Dazhong Yin, and É ric Giroux

CMAQ Nucleation Algorithms and their impact on PM modeling results in the Lower Fraser Valley. Helmut Roth, Weimin Jiang, Dazhong Yin, and É ric Giroux. National Research Council of Canada Ottawa, Canada. Introduction Nucleation Rates Impact on PM Conclusions & future work.

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Helmut Roth, Weimin Jiang, Dazhong Yin, and É ric Giroux

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  1. CMAQ Nucleation Algorithms and their impact on PM modeling results in the Lower Fraser Valley Helmut Roth, Weimin Jiang, Dazhong Yin, and Éric Giroux National Research Council of Canada Ottawa, Canada

  2. Introduction • Nucleation Rates • Impact on PM • Conclusions & future work

  3. Introduction • Episode: Pacific ’93 (1993 Jul 31 – Aug 07) • Emissions: SMOKE, Giroux, É. et al • Meteorology: MM5, Yin, D. et al • Domain • Nucleation Algorithms

  4. Horizontal domains

  5. Nucleation parameterizations & algorithms • HK98: Harrington and Kreidenweis (1998) • Fully coupled equations of 2-mode 2-moment model • implemented in aero2 • KLPx: Kulmala et al (1998) • Equations of classical nucleation theory • Implemented in aero2, aero3: KLP2, KLP3 • Differencesin number distribution, density • sulphuric acid – water system

  6. Nucleation rates: modeling

  7. 1st layer domain-average number rates

  8. 1st layer domain average ASO4I rates

  9. 1st layer number rate statistics all maxima occur in cell (17,8) Neptune Beach

  10. Time-average, 1st layer number rate

  11. Correlation at time of peak nucleation r2=0.9 Aug 05 13:00

  12. Impact on PM concentrations: model runs • Common inputs • Full gas phase calculations • All aerosol processes • Different nucleation algorithms: • NOOP HK98 KLP2 KLP3

  13. Number concentration PM2.5 i-mode

  14. Time-average, 1st layer NUMATKN

  15. Sulphate (ASO4) concentration PM2.5 i-mode

  16. Time-average, 1st layer ASO4I

  17. Main Conclusions • KLP2 and KLP3 results very similar • KLPx had greatest individual cell rate. • HK98 had greatest average rates. • HK98 more responsive to [SULAER] fluctuations. • HK98 increases number concentration over NOOP; KLPx does not. • No increase in PM2.5 SO4 mass over NOOP.

  18. Future work • Impact of nucleation algorithms on model performance using ambient number concentration data

  19. Acknowledgements • U.S. EPA: CMAQ source code • Environment Canada: emissions and met data, ambient PM mass data • Program of Energy Research and Development (PERD) in Canada: funding support

  20. Thank you !

  21. Time-average, 1st layer mass rate

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