Improving Terrain and Land Use Representation in Modeling the Playa Breeze Using the Weather Research and Forecast Model

The aim of this model-based study is to investigate the Advanced Research Weather Research and Forecasting Model's (WRF-ARW, although WRF from hereout) ability to predict the occurrence and three-dimensional structure of playa breezes occurring in Dugway Proving Ground, Utah using sub-km nesting in addition to improved land use and terrain datasets (as compared to the default datasets provided with WRF). A playa breeze is a thermally forced air circulation that develops near the edge of playas, which have properties distinct from the surrounding land cover, including a higher thermal conductivity, a higher albedo due to the presence of a thin salt crust at the surface, sparse vegetation cover relative to the surrounding land cover, and a higher latent heat flux. The combination of each of these characteristics produces a thermally direct circulation, with low-level flow away from the playa during the day and toward the playa at night, resulting in the cooling of the playa during the day and the warming of the playa at night. Improving the WRF model's ability to predict playa breezes is accomplished by performing several tasks. First is improving the spatial resolution of digital mean terrain elevation input using the U.S. Geological Survey (USGS) GMTED2010 data, and then next is upgrading the land use spatial resolution and categories using the National Land Cover Database (NLCD) 2006 dataset. The final task is to add finer WRF horizontal (450 m grid spacing) and vertical (90 levels) resolution to improve upon those used in past studies of the local Playa breeze circulation. The research will examine the WRF's ability to resolve the full three-dimensional structure of the playa breeze direct circulation, using special observations provided courtesy of the Mountain Terrain Atmospheric Modeling and Observation Program (MATERHORN), an ongoing Multidisciplinary University Research Initiative (MURI) sponsored by the Office of Naval Research with the University of Notre Dame acting as Project Lead. This study will be a collaboration between UTEP, the U.S. Army Research Laboratory (ARL), National Center for Atmospheric Research (NCAR), and scientists involved with the MATERHORN research group.