P5.12
An evaluation of boundary layer and land surface parameterizations using data from the VTMX field campaign in the Salt Lake City Valley
Shiyuan Zhong, PNNL, Richland, WA; and J. D. Fast
During October 2000, the Vertical Transport and Mixing (VTMX) field campaign, sponsored by the Department of Energy's Environmental Meteorology Program, took place in the Salt Lake Valley. The VTMX campaign produced an extensive data set for characterizing boundary layer processes governing vertical transport and mixing in an urban valley. In this paper, we used both surface and upper air data from the time period of weakest synoptic winds during the month-long field campaign to evaluate the influence of boundary layer and land surface parameterizations on model simulations of terrain-induced flows and boundary layer evolution in the valley. The MM5 model was chosen because of its availability of a suite of boundary layer schemes. The simulations used 5 nested grids with the innermost grid of approximately 500 m grid spacing that encompasses the entire valley. The results show surprisingly consistent behaviors in most of simulated boundary layer properties when three different boundary layer schemes, namely, Blackadar, MFR, and Gayno-Seaman schemes, were used. The largest differences occurred among simulated mixed depths where TKE-based scheme produced much lower depths than those with K-based schemes. The simulated boundary layer characteristics are, however, much more sensitive to land surface parameterization and in some aspects the more sophisticated OSU/ETA scheme did not necessarily outperform the simple slab scheme.
Poster Session 5, ABL Parameterizations; Marine BLs
Thursday, 18 July 2002, 2:00 PM-2:00 PM
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