1. Impact of Mexico City on Regional Air Quality Louisa Emmons Jean-François Lamarque NCAR/ACD

2. Chem-Climate WG White Paper Hemispheric pollution to regional air quality: An issue of resolution Louisa Emmons, Lyatt Jaegle, Loretta Mickley Scientific advances to be accomplished within this project 1) Improved understanding of feedbacks between climate change and air pollution: effects of changing temperatures/precipitation/water vapor on chemistry, effects of changing emissions (biogenic NOx and VOC, lightning NOx, biomass burning, anthropogenic emissions), effects of changing meteorology (synoptic and hemispheric scales, stratosphere-troposphere exchange). 2) Improved understanding of feedbacks between climate change and export of pollution to the global atmosphere: will a warmer climate lead to more efficient export of pollution? How will it affect the long-range transport of pollution? 3) Improved understanding of the horizontal resolution needed to accurately predict the influences of future climate change on regional air quality and vice versa, through the use of the Weather Research and Forecasting (WRF) model in conjunction with CAM. 4) Exploration of the possibility of downscaling global simulations for analysis of regional air quality.

3. MILAGRO March 2006 Comprehensive set of measurements from city to regional scales INTEX-B - NASA - DC-8 based in Houston MIRAGE-Mex - NSF - C-130 based in Veracruz; ground measurements MAX-Mex - DOE - G1 MCMA - Molina Center - surface and mobile lab

4. Model Simulations Meteorology: NCEP/GFS analyses (42 levels) Emissions: anthropogenic: POET-2000 and Mexico NEI (1999) biomass burning: GFED-2 and C. Wiedinmyer’s N.America calculations (MODIS daily fire counts) MOZART-4 T42 (2.8°) T85 (1.4°) T170 (0.7°) CAM-Chem 0.47°x0.63°

5. Model Evaluation Comparison to C-130 measurements - all flights binned by altitude Finer resolution generally matches observations better Mexico City points

6. Model Evaluation Comparison to surface measurements (T1) O3 [ppbv] CO [ppbv] Acetone [ppbv]

7. Ozone from Mexico City - March 2006 NO emissions from Mexico City are “tagged” to quantify O 3 production Average over March 2006, surface to 400 hPa T85 has higher concentrations over Mexico City, but not larger regional impact NO emissions POET emissions inventory

8. March 19 strong outflow event T85 - higher O3 throughout plume than T42 CAM-Chem - higher O3 over city but weaker plume C-130 data will be used to evaluate 2.8° 1.4°0.5°

9. Radiative forcing of Mexico City emissions CAM-Chem, 0.47x0.63 resolution, driven by NCEP-GFS winds W/m 2 Shortwave flux at the surface 24-hour average

10. CAM-Chem/DART in support of ARCTAS Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) NASA aircraft campaign coincident with NOAA and DOE experiments Part of POLARCAT/IPY April - Fairbanks - Arctic haze, surface halogen chemistry July - near Edmonton - Boreal wildfires Chemical Forecasts EnKF Data Assimilation: met obs, MOPITT CO, MODIS AOD Then free-running forecasts (5 days) for flight planning Post-campaign Analysis Evaluate and improve CAM- Chem Interpret aircraft and satellite observations