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U.S. EPA MODELS-3/CMAQ - STATUS AND APPLICATIONS
Citation:
Schere, K L. U.S. EPA MODELS-3/CMAQ - STATUS AND APPLICATIONS. Presented at US/German Ozone/Fine Particle Science and Environmental Chamber Workshop, Riverside, CA, October 4-6, 1999.
Impact/Purpose:
The objectives of this task are to continuously develop and improve the Community Multiscale Air Quality (CMAQ) modeling system, which is the science implementation within the Models-3 system framework for air quality simulation. CMAQ is a multiscale and multi-pollutant chemistry-transport model (CTM) that includes the necessary critical science process modules for atmospheric transport, deposition, cloud mixing, emissions, gas- and aqueous-phase chemical transformation processes, and aerosol dynamics and chemistry. It relies on Models-3 I/O API to support machine independent data access and maintains simple interfaces among science processor modules to provide a high-level of modularity.
Description:
An advanced third-generation air quality modeling system has been developed by the Atmospheric Modeling Division of the U.S. EPA. The air quality simulation model at the heart of the system is known as the Community Multiscale Air Quality (CMAQ) Model. It is comprehensive in scope and allows for the simulation of ozone and photochemical oxidants, acid deposition, and fine and coarse particles at spatial scales ranging from urban to regional. The model is contained within a computational framework, Models-3 (for 3rd generation), that enables users to interact with the modeling system through a high-level graphical user interface and also facilitates data transmission among the components of the system and provides for analysis, graphics, and visualization capabilities for model simulation results. The modeling system is available from the U.S. EPA (see web site: www.epa.gov/asmdnerl/models3/), and is currently being evaluated for photochemical oxidants and fine particles using field study databases from the eastern United States from 1990 and 1995. The CMAQ is also being extended to include the modeling of selected air toxics, including atmospheric mercury and atrazine (a pesticide).
Models-3 is a sophisticated computational framework for air quality modeling systems. It has been designed and programmed using object-oriented principles (in C++ language). At the highest level, Models-3 presents a graphical user interface (GUI) to the model user. Components presented include the Program and Dataset Managers, for registering programs and datasets; Science Manager and Model Builder for defining science process components and building an executable model, Study Planner for defining and running the required preprocessors and models, Strategy manager for defining emission control strategies and processing emissions, and Tools Manager which is the gateway to the analysis and visualization tools. Models-3 assists the user in setting up new model domains and applications, accessing and tracking data files, and controlling the flow of data and model runs. Component models may be run on the same computer platform as Models-3, or on remote computers where communications links are maintained to the Models-3 server. A configuration currently used at the U.S. EPA has the Models-3 server maintained on a SUN workstation with CMAQ model runs initiated on remote CRAY supercomputers linked to the workstation through fast telecommunication lines.
The most recent release of the Models-3 framework is compatible with SUN workstations