O UTLINE Why are we interested in linking GEOS- CHEM with regional air quality model (CMAQ)? Technical issues to consider when linking GEOS-CHEM & CMAQ Upcoming results from two relevant EPA projects

Why does EPA want to link GEOS-CHEM with regional air quality model (CMAQ)? – Intercontinental transport of pollutants  What are the impacts of trans-Pacific transport of O3, PM, and other pollutants on U.S. air quality?  How about trans-Atlantic transport (export)? – Climate and Air Quality studies  Climate change impacts on air quality  Air quality impacts on climate – Continental domain CMAQ simulations  Can model results improve using the boundary conditions provided by the GEOS-CHEM?

U.S. CMAQ Modeling: O 3 (e.g., 1996 July Max in ppb)

USEPA Community Multiscale Air Quality Model (CMAQ) Gas phase chemical mechanisms: SAPRC99, CB4, RADM2 Aerosols: Binkowski and Roselle [JGR, 2003] Resolution ranges from regional (e.g., 36 km 2 grid) to urban (e.g., 4 km 2 grid) scale Vertical layers range (e.g., 15 to 23) and go up to 100mb Emission fields based on USEPA National Emissions Inventory (e.g., NEI99 v2), BEIS 3.10, and Mobile 6 Meteorology typically generated using the NCAR/Penn State Mesoscale Model (MM5 v3)

GEOS-CHEMSAPRC-99CB4 Ox NOx HNO3 N2O5 HNO4 CO H2O2 CH2O SO2 PAN PMN PPN C2H6 ALK4 C3H8 PRPE ACET MEK ALD2 RCHO ISOP MVK MACR MP R4N2 SO4 NH3 NH4 NO3 (p) DMS MSA Ox (O3+NO2) NOx (NO+NO2) Nitric Acid N2O5 Peroxynitric Acid CO Hydrogen Peroxide Formaldehyde SO2 PAN MPAN PPN Ethane Alkanes(>=C4) Propane Propene Acetone Ketones(>C3) Acetaldehyde Aldehyde(>C3) Isoprene Methylvinylketone Methacrolein Methyl Hydroperoxide Alkylnitrate(>C3) Sulfate Ammonia Ammonium Particulate Nitrate Dimethyl Sulfate Methyl Sulfionic Acid O3, NO2 NO, NO2 HNO3 N2O5 HNO4 CO H2O2 HCHO SO2 PAN MA_PAN PAN2 ALK1 ALK3+ALK4+ALK5 ALK2 OLE1 ACET MEK CCHO RCHO ISOPRENE MVK METHACRO COOH RNO3 ASO4I+ASO4J NH3 ANH4I+ANH4J ANO3I+ANO3J O3, NO2 NO, NO2 HNO3 N2O5 PNA CO H2O2 FORM SO2 PAN 0.4*PAR 4*PAR 3*PAR (1*OLE)+ (1*PAR) 3*PAR 4*PAR ALD2 ISOPRENE ISPD (products of isoprene rxns) UMHP 2*NTR ASO4I+ASO4J NH3 ANH4I+ANH4J ANO3I+ANO3J

Spatial Resolution Issues Scale of CMAQ simulations –regional (e.g., 36×36 km 2 ) scale –nested finer scale (e.g., 12×12 km 2, 4×4 km 2 ) –Hourly time scale for input and output Matching GEOS-CHEM fields with CMAQ for boundary conditions –If 4  ×5 , > 10 CMAQ grids to 1 GEOS-CHEM grid along vertical boundaries –Different projections (cartesian vs conformal)

CMAQ upper boundary conditions CMAQ typically up to 100 mb With fairly coarse layers at top, tropopause not resolved Without tropopause dynamics, lower stratospheric [O 3 ] not an option O 3 fluxes from GEOS-CHEM would be an option

Consistencies between GEOS-CHEM and CMAQ Emission inventories over U.S. Global Climate Modeling for future climate change scenarios –MM5 mesoscale model can use GCM BCs –Similar greenhouse gas scenarios Chemical fields simulations –O 3 –Speciated aerosols (sulfate, nitrate, organics,…) –Hg

Upcoming results from 2 relevant EPA studies Climate Impacts on Regional Air Quality (CIRAQ): USEPA ORD Intercontinental transport and Climate Effects of Air Pollution (ICAP): USEPA OAQPS

Simulations from CIRAQ Project (Climate Impacts on Regional Air Quality) For U.S. Continental Domain 10-yr MM5 mesoscale model runs (complete 2004) – – ×36 km 2 resolution GISS II’ GCM boundary conditions (collaboration with Harvard) IPCC A1B greenhouse gas emission scenario 5-yr CMAQ simulations (complete 2006) – – O 3 and PM predictions 36×36 km 2 resolution Base NEI99 v2 emissions for 1 st incremental phase tests SAPRC chemical mechanism Boundary conditions driven by GEOS-CHEM (with GISS II’ GCM, IPCC A1B) (collaboration with CMU and Harvard, through STAR EPA coops) Analysis of results included in EPA GCRP air quality national assessment report in 2007

Future (2050) air quality emission scenarios –Technology assessments for mobile and utility sectors –Population and economic projections consistent with IPCC, more spatially resolved –External collaborations to be determined –Proposals under review at STAR program CMAQ 2050 simulations with future air quality emission scenarios (tentatively planned for 2010 EPA GCRP AQ assessment) Simulations from CIRAQ Project (Climate Impacts on Regional Air Quality)

Results from ICAP Project (Intercontinental transport and Climate Effects of Air Pollution) 2001 trans-Pacific and trans-Atlantic domain CMAQ simulations, 108-km grid (spring 2004) 2001 national domain CMAQ simulations, 36-km grid; episodic eastern & western US domains, 12-km grid (spring/summer 2004) Emission inventory for Asia (O3, PM, Hg)

ICAP Trans-Pacific Domain ICAP Trans-Atlantic Domain

ICAP: Refinement of Asian emission inventory for CMAQ Trans-Pacific Simulations NO emissions

Air Quality Modeling over China : PM 2.5

Next Directions at EPA Assessment of future climate change impacts on AQ expanded to 2100 Develop bidirectional feedback between CMAQ and MM5/WRF for aerosol impacts on meteorology Agency long-term planning for intercontinental transport research underway