Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy Jonathan Pleim, Shawn Roselle, Jeffrey Young, Gerald Gipson, Prakash Bhave, Rohit Mathur USEPA/ORD NOAA/ARL Research Triangle Park, NC New Developments in The Community Multiscale Air Quality (CMAQ) Model

Outline  Two development tracks Community version Community version Air Quality Forecasting version Air Quality Forecasting version Synergistic development Synergistic development  New features of 2004 release  Future developments

Two Tracks  Community version Annual public releases (via CMAS) Annual public releases (via CMAS) Designed for retrospective modeling for policy and research Designed for retrospective modeling for policy and research Multiple configurations Multiple configurations  Air Quality Forecasting Operational Ozone and PM forecasts Operational Ozone and PM forecasts Integrated with NCEP forecast systems Integrated with NCEP forecast systems Single optimized configuration Single optimized configuration

CMAQ Modeling System SMOKE Anthro and Biogenic Emissions processing Fifth Generation Mesoscale Model (MM5) (WRF in 2005) CMAQ AQ Model- Chemical-Transport Computations Met-Chem Interface Processor (MCIP) Met. data prep NOAA Weather Observations EPA Emissions Inventory Hourly 3-D Gridded Chemical Concentrations

Eta-CMAQ AQF System PREMAQ Processor- Emissions, Met. data prep NCEP Mesoscale Meteorological Model (Eta) CMAQ AQ Model- Chemical-Transport Computations Eta-Postprocessor- Vertical interpolations Product Generator- Horizontal interpolations Weather Observations EPA Emissions Inventory Hourly 3-D Gridded Chemical Concentrations

WRF-CMAQ AQF System (coming in 2005) PREMAQ Processor- Emissions, Met. data prep NCEP Mesoscale Meteorological Model (WRF-NMM) CMAQ AQ Model- Chemical-Transport Computations Weather Observations EPA Emissions Inventory Hourly 3-D Gridded Chemical Concentrations

Synergistic Development Community release AQF system Faster gas-phase chemical solver (EBI) Aerosol model upgrades And efficiency improvements Modified minimum K z Updated Chem Mechanism (CB4) (coming in 2005) Mass conservation scheme New Photolysis model Fast TUV (coming in 2005) Modified cloud cover and convective cloud transport

CMAQ upgrades  The 2003 release and the 2004 release can be viewed as two parts of a comprehensive upgrade of the CMAQ model. Many important scientific advances were made for the 2003 release. Many important scientific advances were made for the 2003 release. Many efficiency improvements made for the 2004 release have dramatically cut model run times. Many efficiency improvements made for the 2004 release have dramatically cut model run times.

New Features of the 2004 CMAQ Release (version 4.4)  Aerosols Coagulation: Replaced numerical calculations for coagulation coefficients with look-up tables Coagulation: Replaced numerical calculations for coagulation coefficients with look-up tables Secondary Organic Aerosols: Improved the “initial guess” for the gas-particle equilibrium solver Secondary Organic Aerosols: Improved the “initial guess” for the gas-particle equilibrium solver About a factor of 2 speedup in Aerosol module Thermodynamics: Corrections to ISORROPIA reduce instabilities in dry conditions (w/ A. Nenes) Thermodynamics: Corrections to ISORROPIA reduce instabilities in dry conditions (w/ A. Nenes) Details of Aerosol changes will be presented by Prakash Bhave

New for 2004 (cont)  Gas Phase Chemistry Added new highly accurate generalized solver: ROS3 – a Rosenbrock solver by Sandu et al. (1997) Added new highly accurate generalized solver: ROS3 – a Rosenbrock solver by Sandu et al. (1997) QSSA discontinued since ROS3 is faster and more accurate QSSA discontinued since ROS3 is faster and more accurate The Euler Backward Iterative (EBI) replaces MEBI for CB4 and SAPRC99 The Euler Backward Iterative (EBI) replaces MEBI for CB4 and SAPRC99 EBI is mechanism specific but we have an EBI solver generatorEBI is mechanism specific but we have an EBI solver generator EBI about twice as fast as MEBI for CB4 w/o aerosolsEBI about twice as fast as MEBI for CB4 w/o aerosols

Corrections  Corrected error in PPM vertical advection which miscomputed flux divergence for non- uniform grid spacing Did not conserve mass Did not conserve mass About 10% error in ground-level concentrations About 10% error in ground-level concentrations  Corrected dry deposition velocity that was in flux form (velocity x air density) Correction reduces dry deposition flux by about 10% Correction reduces dry deposition flux by about 10%

Other Updates  The Plume-in-Grid feature now includes aerosols (see Godowitch’s poster)  Computational efficiency has been improved through collaboration with Sandia National Laboratory Improved MPP scalability through revision of the parallel I/O system Improved MPP scalability through revision of the parallel I/O system Code optimization Code optimization

Expected Upgrades for 2005  Extension of the aerosol module to include sea salt with heterogeneous interactions with gas- phase species  Updates to the CB4 gas-phase chemical mechanism  Linkage to the WRF meteorology model  A new hybrid local and non-local closure PBL model  New Photolysis model – Fast TUV  Generalized aqueous chemistry solver

 Minimum K z according to Urban LU  Mass conservation scheme Vertical velocity derived from mass continuity Vertical velocity derived from mass continuity  Modification of subgrid convective cloud transport  Modified cloud cover scheme AQF system to be described by Rohit Mathur Modifications for 2005 from AQF System Urban Fraction

Additional Capabilities for 2005 Release  Sulfate tracking model Accounting of production pathways Accounting of production pathways  Primary carbonaceous aerosols source apportionment Source types or geographic regions Source types or geographic regions  Toxics and Mercury will be included in release