Numerical modeling of atmospheric behavior in the Salt Lake Valley during VTMX 2000 (Utah)

This dissertation describes the use of the Advanced Regional Prediction System (ARPS), developed at the Center for Analysis and Prediction of Storms, University of Oklahoma, for simulation of air flows such as those observed during the field campaign of the Vertical Transport and Mixing eXperiment (VTMX). The VTMX field campaign was carried out in the Salt Lake Valley during October 2000. ARPS interpolated a background field from the ETA model to a coarse ARPS model grid with horizontal spacing of 20 km. Outputs from simulated results on that grid have served as inputs for one-way nested grid runs on finer grids with horizontal resolution of 5 km, 1 km, 500 m, 250 m and 100 m. Results are given for high-resolution simulations of flow in the area of the Salt Lake Valley.; The ARPS code was used to simulate two Intensive Operation Periods (IOPs) of the VTMX field campaign. The simulations capture the evening transition period well. When drainage flows developed during the night, the high resolution simulated results revealed some interesting flow features that resembled hydraulic jumps, bores, wave initiation and Bernoulli effects. This research studies the effects of grid resolution on the simulation. The results show that the increased horizontal and vertical resolution improved the prediction of the surface potential temperature and the vertical structure. The simulation results are very sensitive to the size and location of the domain. Significant improvement in the prediction of vertical wind and temperature profiles were found with a larger domain including more topography that influences the flow.; A new dataset of ground surface characteristics was created by merging the 30-m National Land Cover Data (NLCD) and ARPS surface data. We developed a new vegetation model to allow multiple vegetation types for each grid cell. The simulation showed that the surface dataset with higher resolution improved the prediction of nighttime surface temperature and daytime surface wind speed.; The Weather Research and Forecast (WRF) model was run for the same IOPs, and the simulated results were compared with those from ARPS. Different turbulence options were tested for ARPS, including a new subfilter-scale (SFS) turbulence model.