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CMAQ 4.7 Release Notes

The Model Development Team is pleased to announce that CMAQ version 4.7 has been delivered to CMAS for public release. You can access the model from the CMAS. Exit EPA Disclaimer.

Below is a list of updates since the version 4.6 release:

  1. Aerosols
    SOA Model Enhancements
    • Updates: isoprene SOA, sesquiterpene SOA, polymerization, acid-catalyzed SOA, NOx-dependent SOA yields, and enthalpy of vaporization
    • In-cloud SOA formation pathways (glyoxal, methylglyoxal)
    • Changes in gas-phase chemistry mechanism, emissions speciation, and biogenic emmissions model, to represent SOA precursor
    Coarse PM
    • Semi-volatile inorganic components (NO3-, Cl-, and NH4+) can condense and evaporate from the coarse mode, via dynamic mass transfer
    • Nonvolatile sulfate can condense on the coarse mode
    • Variable standard deviation of coarse mode size distribution
    • Emissions of sea salt from the surf zone
    • Heterogeneous reaction probability
    • Re-derived parameterization based on Davis et al. (2008)
  2. Chemistry
    HONO enhancements
    • Heterogeneous reaction on aerosol and ground surfaces
    • Emissions from mobile sources
    Photolysis Options (beta versions)
    • In-line photolysis rate module, with aerosol feedback
    • Photolysis rates adjusted using satellite-derived cloud information (currently table-approach only)
    Aqueous Chemistry
    • Added two organic oxidation reactions (glyoxal, methylglyoxal)
    • Updates to Henry's Law constants based on literature review
    Multi-pollutant Capability
    • Include HAPs and Hg in single modeling platform
  3. In-line Options
    • Moved calculation into CCTM
    • Integrated BEIS into CCTM
    • Incorporated Plume-rise into CCTM
    • Bi-directional NH3 and Hg surface flux for NH3, fertilizer emissions will be applied through the fluxmodel (under development)
  4. Emissions
    • Speciation changes for HONO and benzene
    • added sesquiterpene emission
    • Updated flux parameterizations & surf zone emissions
    • Used spatial allocator to produce ocean file
  5. Clouds
    Convective cloud model
    • Revised to reduce layer configuration differences
    • Changed the integration timestep
    Resolved cloud model
    • Correction in precipitation flux calculation
  6. Diagnostic Tools (will be released during FY09)
    • Direct Decoupled Method (DDM)
    • Primary carbon source apportionment model
    • Sulfate tracking model
  7. Model options no longer supported:
    • Plume-in-grid
    • CB4 mechanisms
    • Aero3 module and AE3 mechanisms
    • RADM cloud module
    • Stand-alone mercury version of CMAQ (capability is included in the multipollutant version)

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