Development of the Operational Multiscale Environment Model with Grid Adaptivity (OMEGA) and its Aerosol Transport and Diffusion Model (ATDM)

The Operational Multiscale Environment Model with Grid Adaptivity (OMEGA) is a new atmospheric simulation system that merges state-of-the-art computational fluid dynamics techniques with a comprehensive nonhydrostatic equation set. OMEGA is based on an unstructured triangular prism grid that permits a horizontal grid resolution ranging from 100 km down to 1 km, and a vertical resolution ranging from a few tens of meters in the boundary layer to 1 km in the free atmosphere. OMEGA contains an embedded Aerosol Transport and Diffusion Model (ATDM) that permits the high-resolution simulation of the advection and diffusion of either Eulerian or Lagrangian parcels. OMEGA is naturally scale spanning, and its unstructured grid allows the addition or subtraction of grid elements at any point in space. This capability allows the model to readily adapt its grid to fixed surface or terrain features and land/water boundaries. The implications for the ATDM are that enhanced grid resolution can be provided in localized regions such as emission sources and receptor locations, or in the vicinity of a dust, smoke, or chemical cloud.