What You Should Know About Air Quality Modeling

1. What You Should Know About Air Quality Modeling Tyler Cruickshank & Patrick Barickman State of Utah Department of Environmental Quality Division of Air Quality

2. λ2 ∫ јA = σA(λ,T)ФA(λ,T)I(λ) dλ λ1 Objective 1: Derive each term of the first-order rate constant for winter-time photolysis . where, јAis the First-order rate constant for photolysis (јA )

3. Modeling Atmospheric Chemistry The Model - CMAQ? What Are People Doing With CMAQ? What You Should Know About CMAQ Results (Challenges).

4. CMAQ is a 3-D Grid Based Model Simulates: Gas phase: NO2, NO, O3, OH, VOC’s, … Aerosol Phase: NH4, NO3, OC, EC, … Wet Deposition Dry Deposition CMAQ

5. Area Point Mobile Biogenic Emissions (SMOKE) CMAQ Model Structure MM5 or WRF Meteorology Interface Processor (MCIP) - Interpolate met fields to CMAQ grid Initial Chemistry Conditions Boundary Chemistry Conditions Gas Phase Chemistry Aerosol Chemistry Too Much Interpolation No Feedback CMAQ

6. CMAQ “Calls” WRF Chemistry Feedback CMAQ Next Generation CMAQ A Coupler Has Been Developed (but not released)

7. CMAQ Applications • Pollution control strategies • Research • Operational air quality forecasting Let’s look at some examples.

8. Annual Ozone Mortalities (cardiopulmonary) Mortalities/1000km Air Pollution & Health Impacts Mortalities/1,000,000 people Casper and West. CMAS 2008

9. Asian Transport Evaluation of Mercury Outflow from East Asia using CMAQ-Hg Lin 2008. CMAS 2008

10. Lightning NOx Emissions Kaynak 2008. CMAS 2008

11. Operational Forecasting 12 km 5 km 2.5 km

12. Utah’s Air Quality Modeling Applications Winter PM2.5 Summer O3 Secondary pollutants Not just dust and “stuff”, but complex gaseous chemistry that creates O3 and PM2.5.

13. Atmospheric Chemistry Modeling Challenges Examples: • Chemistry based on “summer” laboratory data. • UV ground surface albedo & photolysis rates. • Poor western landuse data and biogenic emissions. W Salt Lake Valley S N E Wont even talk about this challenge …

14. Chemistry Based on “Summer” Laboratory Data Challenge #1 Chemistry Based on Summer Laboratory Data ► Model development history Where: California, Eastern US Ozone When: Chemical Mechanisms: 1970’s – 1980’s First CMAQ: June 1998 ►Today’s wide ranging applications & challenges CONUS 365 days/year

15. Wasatch Front’s Winter-Time Challenge PM2.5: Ammonium Nitrate (NH4NO3) HNO3 + NH3 Wasatch Front Inversion PM2.5 Components

16. Ammonium Nitrate (NH4NO3) Particulate Nighttime Pathway to HNO3 N2O5 + H2O -> HNO3 1) N2O5 lab data performed at 293+ K Daytime Pathway to HNO3 O3 + λ -> O2 + 2 OH NO2 + OH -> HNO3 2) Ultra Violet (UV) Radiation

17. UV Ground Surface Albedo Challenge #2 Ultraviolet Radiation ultimately creates O3 and HNO3 Incident Scattered O3 Actinic flux = Incident + Scattered + Reflected Reflection

18. Estimated UV Albedo Values Croplands: 0.37 Grasses: 0.72 CMAQ/JPROC Uses 0.05 Evergreens: 0.27 “Bare” Ground: 0.83 Data from Tanskanen and Manninen (2007)

19. Photolysis Rate Sensitivity to UV Albedo January 18 July 18 NO2 Photolysis Rate

20. CMAQ Results: O3 @ 1400 MST - Difference Plots 0.85 Maximum Hourly Concentration Change

21. Poor Western Landuse Data & Biogenic Emissions Challenge #3 Biogenics (VOC’s) play a significant role in atmospheric chemistry. Some biogenic species are highly reactive WRT the formation of ozone. Gamble Oak: Isoprene Juniper, Saltbush: λ-pinene Rabbitbrush: Limonene Sagebrush: Other monoterpenes

22. Landuse Data & Biogenic Emissions Q: All “Shrublands” = ? A: Probably Not …. Species? Leaf Area Index? Species Emission Factors? * This is an issue in met modeling as well. Categorized as USGS Shrubland

23. Biogenics and Ozone Formation Biogenics Impact on Ozone (CMAQ Model – July 2005) Salt Lake City + Logan +

24. Conclusions Time-Science.com • Significant challenges exist • (external/internal) • It is the only tool that we have so … • Utah is up a creek. • But progress is being made.