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A2C is a single model, which allows the information between the mesoscale and CFD models to interact in a two-way flow, realistically mimicking actual atmospheric conditions. A2C also considers the thermal (cooling/heating) effects of buildings, something that neither mesoscale models nor CFD models are able to accomplish. For example, during daylight hours, one side of a building is usually cooler than the other side; this affects the airflow around the building. A2C can simulate a forecast of air flows and the transport and dispersion of air pollutants—an important feature when accuracy counts.

A2C predicts and presents the physics of airflow and air-borne particle diffusion, including:

  • Airflow around buildings
  • Single model seamlessly integrate from mesoscale to microscale
  • Thermal effects on buildings on airflows
  • Three-dimensional forecast
  • Second-moment turbulence closure
  • Complex terrain
  • Tall tree canopy
  • Land use (roughness, albedo, soil moisture, anthropogenic heat)
  • Ensemble cloud model
  • Shortwave and longwave radiation parameterization in fog and clouds
  • Precipitation microphysics
  • Non-hydrostatic pressure
  • Non-neutrally buoyant plume
  • Concentration fluctuation


  • 3D Animation
  • Nested grid
  • Four-dimensional data assimilation
  • Interface with tower, rawinsonde, and large-scale weather data
  • Vertical profile plots of wind, temperature, and turbulence
  • Wind vector distribution plots in the vertical and horizontal cross section
  • Surface concentration contour plots
  • Vertical cross section plots of concentration contours


  • Runs on UNIX, LINUX, and Windows environments
  • Runs on desktop and laptop workstations and PCs
  • User friendly menu system
  • Terrain data extraction interface for a HOTMAC input file
  • 3-d visualization interface for animation
  • Restart capability