1. GEOS-CHEM Modeling for Boundary Conditions and Natural Background James W. Boylan Georgia Department of Natural Resources - VISTAS National RPO Modeling Meeting Denver, CO May 25, 2004

2. Outline Objectives and Background Summary of Modeling Results Update on RPO GEOS-CHEM Project Natural Background Options Group Discussion

3. Objectives Run the GEOS-CHEM global chemical transport model for CY2002 to develop temporally and spatially varying boundary conditions (BCs) for the 36-km national modeling grid to be used for ozone, PM 2.5, and regional haze modeling. Run GEOS-CHEM to evaluate natural background visibility and transboundary pollutant transport.

4. GEOS-CHEM Global Chemical Transport Model Driven by Goddard Earth Observing System (GEOS) assimilated meteorological data from the NASA Data Assimilation Office (DAO) Horizontal resolution 1 o x 1 o to 4 o x 5 o (user-selected), 48 levels in vertical (80 km) Ozone-NO x -VOC (“oxidant”) chemistry: ~80 species, 400 reactions Aerosols: H 2 SO 4 -HNO 3 -NH 3, organic carbon (OC), elemental carbon (EC), soil dust (four size classes), sea salt (two size classes) Oxidant and aerosol simulations coupled by photolysis frequencies, heterogeneous chemistry, sulfate/nitrate formation, HNO 3 (g)/NO 3 - partitioning Multi-process wet deposition scheme http://www-as.harvard.edu/chemistry/trop/geos

7. 3-Hourly GEOS-CHEM Sulfate BCs EPA Default

8. SO4 Seasonal Boundary Condition Time Series Summer

9. (July monthly avg., 2001) PM diff. (GCM BCs/ICs – Default BCs/ICs)  PM 2.5  PM Sulfate Slide provided by: Carey Jang, U.S. EPA

10. PM diff. (GCM BCs/ICs – Default BCs/ICs)  PM 2.5  PM Sulfate (July 22, 2001, daily average) Slide provided by: Carey Jang, U.S. EPA

11. (January monthly avg., 2001) PM diff. (GCM BCs/ICs – Default BCs/ICs)  PM 2.5  PM Nitrate Slide provided by: Carey Jang, U.S. EPA

12. PM diff. (GCM BCs/ICs – Default BCs/ICs)  PM 2.5  PM Nitrate (Jan. 13, 2001, daily average) Slide provided by: Carey Jang, U.S. EPA

13. January 2002 Episode GEOS-CHEM (S) vs. EPA-Default CASTNET TNO3 (VISTAS) CASTNET TNO3 (US)

14. Summary of Results Summer Episodes –Significant change in ozone in WRAP, MRPO, and MANE-VU –Significant change in PM 2.5 (sulfate) in WRAP Winter Episodes –Significant change in PM 2.5 (nitrate) in MRPO, MANE- VU, and VISTAS – related to ozone or reactive nitrogen BCs (?) –Ozone performance worse (low bias) – BC low in north –NO 2, NO 3, and TNO 3 performance better Mexican Fires –Significant change in PM 2.5 (OC & EC) in CENRAP, WRAP, VISTAS, and MANE-VU

15. GEOSCHEM ; DAO Comparison of Wind Fields GEOSCHEN : Westerly (inflow) MM5 : Northerly (outflow)

16. GEOSCHEM : Easterly and northerly MM5 : Clock wise rotation motion

17. Possible inconsistencies between the global and regional scale dynamics MM5 Outflow and GEOS-CHEM Inflow  OK GEOS-CHEM Outflow and MM5 Inflow  Problems Remedy (being tested by UH) Run regional scale model with global scale output as input for initialization and analysis nudging Too late to use this remedy for VISTAS modeling Other Options? In the case where GEOS-CHEM outflow and MM5 inflow, could replace hourly BC with seasonal average BC or seasonal average inflow BC Linking GEOS-CHEM and CMAQ

18. GEOS-CHEM Modeling for RPOs Daniel Jacob (Harvard) will be performing annual (CY2002) GEOS-CHEM modeling for the RPOs Project is being managed by a steering committee comprised of representatives from all 5 RPOs –VISTAS volunteered to take the lead Workplan identifies three major tasks to be completed by August 31, 2004 VISTAS is funding Daewon Byun (UH) to convert GEOS-CHEM outputs to boundary conditions for CMAQ (CAMx?)

19. Harvard Deliverables Global Emissions Inventory for CY2002 –Biomass burning inventory with 1°x1° resolution GEOS-CHEM global 3-D concentration fields (4°x 5° grid) with 3-hour resolution for three full-year simulations –Baseline 2002 simulation with all anthropogenic emissions –Sensitivity simulation with U.S. anthropogenic emissions turned off –Sensitivity simulation with worldwide anthropogenic emissions turned off Model Performance Evaluation (MPE) –IMPROVE and CASTNET –Monthly mean SO4, NO3, TNO3, NH4, OC, EC, and dust –Extensive MPE conducted under EPRI funding

20. Natural Background Runs The GEOS-CHEM model results can be used to evaluate natural conditions at Class I areas “Directly Method”: Turn off U.S. anthropogenic emissions in GEOS-CHEM and examine pollutant concentrations at Class I areas –4°x5° resolution too coarse to be useful (especially for mountainous and costal sites) –1°x1° resolution will be more useful than 4°x 5° resolution, but still might not meet our needs Results available through EPRI funding in Fall 2004

21. 4°x 5° GEOS-CHEM Grid

22. Natural Background Runs “Indirect Method”: Turn off U.S. anthropogenic emissions in GEOS-CHEM to generate a new set of BCs that will be used for a CMAQ run at 36/12 km resolution with U.S. anthropogenic emissions turned-off. –New boundary conditions must be generated with GEOS-CHEM (no U.S. emissions) to eliminate recirculated U.S. anthropogenic emissions from the boundary conditions –Advantages: finer grid resolution, better meteorological fields, more advanced air quality model –Disadvantages: time and $$$ Same concepts for evaluating “true” natural conditions by removing worldwide anthropogenic emissions in GEOS-CHEM.

23. 4°x 5° GEOS-CHEM Grid

25. Discussion Issues Options for addressing inconsistencies between the global and regional meteorological fields? Natural Background Simulations –Direct or Indirect Method? –Turn-off U.S. anthropogenic emissions or turn-off all North American anthropogenic emissions? Boundary Conditions for 2002 “typical” and 2018 “typical” CMAQ simulation –Use 3-hour GEOS-CHEM BCs or use seasonal average GEOS-CHEM BCs or use seasonal average inflow/outflow BCs? Other Issues?