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CMAQv5.0 Beta Release (May 2011)
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The Community Multiscale Air Quality (CMAQ) modeling system Version 5.0
(CMAQv5.0) is scheduled for release in September 2011.  To facilitate
community contributions to this model release, a "Beta" version was
created and made available to external collaborators/developers on May
5, 2011.  There are several new features included in this release.  This
Beta version will undergo extensive application and evaluation over the
next few months, which may lead to additional changes before the final
release in this fall.  Contact the U.S. EPA Atmospheric Model
Development Branch (Jon Pleim - pleim.jon@epa.gov) if you would like to
access the new model version.

The aerosol module was redesigned to eliminate dependencies and
duplication across modules. The speciation of PMOther was improved by
adding 9 new PM2.5 species, including primary non-carbon organic matter
(NCOM), and particulate Fe, Al, Si, Ti, Ca, Mg, K and Mn.  Anthropogenic
emissions of 4 existing PM2.5 species (NH4, Na, Cl and H2O) are now
included.  In addition, modeled Fe and Mn concentrations are now
explicitly used to catalyze aqueous oxidation of SO2 to sulfate.  An
oxidative aging reaction was added for primary organic aerosol.  There
were some minor updates to the SOA yield parameterization.  A new
aerosol thermodynamics module was included (ISORROPIAv2).  An optional
algorithm for windblown dust was added to the CMAQ model.

The Carbon Bond (version 05) chemical mechanism (CB05) now includes
updated the toluene chemistry, revised rate constants for N2O5
hydrolysis based on the latest recommendation of IUPAC, and additional
reactions of toluene and xylene with chlorine radical.  A new version of
the SAPRC mechanism (SAPRC07TB & TC) was integrated into CMAQ, and
includes fully updated organic and inorganic reactions, updated
photolysis rates, operator species to better represent chemical
reactions in low-NOx conditions, explicit treatment of additional
species with high emission, high toxicity, or high SOA formation, and an
updated isoprene mechanism.

The inline photolysis rate module was improved to increase flexibility
by reading input data from an ASCII file (created by a pre-processor)
for easy modification/introduction of associated data (e.g., quantum
yield, cross section) for new reactions, and an algorithm is now
included that calculates the surface albedo based on land use
categories, zenith angle, seasonal vegetation, snow and sea ice
coverage.

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