The HOTMAC/RAPTAD system is a user-friendly, cost effective way to simulate various what-if scenarios in the computer, which is impossible to do with field measurements, but necessary for planning or mitigating potential environmental catastrophes.

HOTMAC (higher order turbulence model for atmospheric circulation) is a three-dimensional mesoscale prediction model that forecasts wind, turbulence, humidity, and atmospheric turbulence distribution over complex surface conditions.

RAPTAD (random puff transport and diffusion) is a three-dimensional Lagrangian random puff model that is used to forecast transport and diffusion of air pollution materials over complex terrain.

Features include non-hydrostatic pressure computation, nested grid, land-use distributions, cloud, fog, precipitation physics. See below for more details.



  • 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
  • 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 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