Operational Multi-Scale Environment Model with Grid Adaptivity, Version 4.0, Volume 1 - Model Enhancements

This report details the status of the Operational Multi-scale Environment model with Grid Adaptivity (OMEGA). OMEGA is a nonhydrostatic atmospheric simulation system, which includes a graphical user interface (GUI), a grid generator, a data preprocessor, the atmospheric forecast model, and visualization postprocessor. it also includes terrain, land-water, and climatological surface datasets, and scripts that allow the model to be setup and run operationally. This report discusses the primary features of OMEGA with special emphasis to the improvements made under this contract. The improvements include a time-splitting scheme which groups the grid cells into masks that can use similar time steps resulting in considerable computational savings; air-surface interaction routines that take into account nonhomogeneous surface properties; a Lagrangian particle model that takes into account turbulent fluctuations in the momentum of air; and scripts which allow the automatic execution of the model from data ingest to results postprocessing. A major improvement to the system has been the dynamic adaptation capability by which the model grid adapts to runtime flow-characteristics to maintain the accuracy of solution and yet save computational cycles. Another modification to improve runtime performance is the addition of Message Passing interface (MPI) calls to implement parallelization. --Original contains color plates: All DTIC reproductions will be in black and white. Prepared in cooperation with MESO, Inc., Troy, NY.