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A comparison of PM 2.5 simulations over the Eastern United States using CB-IV and RADM2 chemical mechanisms. Michael Ku, Kevin Civerolo, and Gopal Sistla New York State Department of Environmental Conservation Albany, NY. INTRODUCTION. Assess CMAQ in simulating PM for two chemical mechanisms
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A comparison of PM 2.5 simulations over the Eastern United States using CB-IV and RADM2 chemical mechanisms Michael Ku, Kevin Civerolo, and Gopal Sistla New York State Department of Environmental Conservation Albany, NY
INTRODUCTION • Assess CMAQ in simulating PM for two chemical mechanisms • Comparison with hourly TEOM (PM 2.5) measurements • Comparison with daily averaged PM2.5 and species data from SEARCH and IMPROVE (MANE-VU) • Sensitivity of the chemical mechanism to emission reductions
MODEL SIMULATIONS • CMAQ (version 4.1) with CB-IV and RADM2 at 36km and 16 vertical layers • MM5 run at 108/36/12 km nesting grids and 25 vertical layers up to about 16 km • 1995 EPA emission data for CB-IV and RADM2 chemistry • Emission reduction simulation: . 50 % reduction in elevated SOx . 50 % reduction in elevated SOx and 50% in elevated NOx
MEASUREMENTS • TEOM hourly PM 2.5 measurements – 15 sites in the modeling domain • SEARCH network -- daily 24-hour PM 2.5, sulfate, nitrate • IMPROVE (MANE-VU) network -- twice a week 24-hour PM 2.5, sulfate and nitrate
Daily averaged PM 2.5 concentrations on July 15, 1999(A) CB-IV; (B) RADM2 (B) (A)
Daily averaged percentage of Sulfate to the total PM mass,(A) CB-IV; and (B) RADM2 (B) (A)
Daily averaged percentage of Nitrate to the total PM mass,(A) CB-IV; and (B) RADM2 (B) (A)
TEOM HOURLY DATA COMPARISON • Scatter plots • Diurnal plots • Statistics
Comparison with 24-hour data from SEARCH and IMPROVE (MANE-VU)
Comparisons with SEARCH data
Compariosn with IMPROVE (MANE-VU) data
EMISSION REDUCTION SIMULATUIN • 50% reduction of elevated SOx emissions • 50% reduction of elevated SOx emissions and 50% reduction of elevated NOx emissions
Percentage reduction of PM 2.5 Concentration at 50% reduction of elevated SOx emission, (A) CB-IV; and (B) RADM2 (B) (A)
Percentage reduction of PM 2.5 concentration at 50% reduction of elevated SOx emission and 50% reduction of elevated NOx emission, (A) CB-IV; and (B) RADM2 (A) (B)
SUMMARY • Both CB-IV and RADM2 overpredicted hourly TEOM PM 2.5 measurements • RADM2 chemistry predicted much higher PM 2.5 concentrations than CB-IV • CB-IV based simulations showed relatively lower sulfate and higher nitrate compared to those of RADM2 • RADM2 chemistry is more sensitive in response to emission reductions than CB-IV