Coupled Atmospheric Chemistry Schemes for Modeling Regional and Global Atmospheric Chemistry
William R. Stockwell
Howard University 27 July, noon in 2155
Abstract:
Atmospheric chemistry models are used for air quality forecasting and
these require chemical reaction mechanisms to simulate the production
of air pollution. Chemical boundary conditions are another necessity
for the simulations. Global models may be used to provide boundary
conditions to regional models. NOAA/NCEP uses the Community Multi-scale
Air Quality Model (CMAQ) for air quality forecasting and one of its
standard chemical mechanisms is the Regional Atmospheric Chemistry
Mechanism, Version 2 (RACM2). The goal of this project is to develop
the Global Atmospheric Chemistry Mechanism (GACM), a global version of
RACM2. GACM is intended for use in global scale atmospheric chemistry
models to provide chemical boundary conditions for regional scale
simulations by models such as CMAQ. GACM includes additional chemistry
for marine environments while reducing its treatment of the chemistry
needed for highly polluted urban regions. This keeps GACM’s size small
enough to allow it to be used efficiently in global models. GACM’s
chemistry of volatile organic compounds (VOC) is highly compatible with
the VOC chemistry in RACM2 allowing a global model with GACM to provide
VOC boundary conditions to a regional scale model with RACM2 with
reduced error. The GACM-RACM2 system of mechanisms should yield more
accurate forecasts by regional air quality models such as CMAQ.