Environmental Engineering Reference
In-Depth Information
of this uncertainty are related to the accurate characterization of atmospheric
loading of aerosols, the chemical composition and source attribution of which is
highly variable both spatially and temporally. The accurate regional characterization
of aerosol composition and size distribution is critical for estimating their optical
and radiative properties and thus in quantifying their impacts on radiation budgets
of the earth-atmosphere system. Hence, coupled regional meteorology and atom-
spheric chemistry models are needed to properly characterize the spatial hetero-
geneity in radiative forcing associated with short-lived aerosol and gases, and,
consequently to better understand their aggregate influence on the earth's radiation
budgets. Coupling the modeling systems provides means for finer scale applications,
wherein higher frequency of data exchange between meteorological and chemistry-
transport calculations is necessary to better represent the effects of meteorological
variability on modeled concentrations.
2. Design of the WRF-CMAQ Coupled Modeling System
Fig. 1.
The coupled WRF-CMAQ modeling system
The design of the coupled WRF-CMAQ system was based on a number of
desired structural attributes: (1) maintain integrity of the WRF and CMAQ (Byun
and Schere, 2006) models, so that both models can evolve independently benefitting
from their respective user and development communities, (2) support both coupled
and the traditional uncoupled modeling paradigms within the same modeling frame-
work to assess their relative benefits for both research and regulatory applications,
(3) maintain flexibility in design to add feedback process representations, and (4)
ensure efficiency in coupling to enable applications from urban to hemispheric
scales. A schematic the coupling of the WRF and CMAQ modeling systems is shown
in
Fig. 1
. In this design, the WRF and CMAQ modeling systems are coupled through
the use of memory resident buffer data files. CMAQ is called from the main “Solve”
