Extended Abstract (1.3M)11.6
Coupled Mesoscale-Microscale Model to Compute Neighborhod Scale Wind Fields
Ronald M. Cionco, US Army Research Laboratory, White Sands Missile Range, NM; and S. A. Luces
The coupling of a mesoscale model to a microscale airflow model with the inclusion of surface morphology features permits further analyses at the neighborhood scale. The Army Research Laboratory (ARL) has long used a microscale High Resolution Wind model (HRW) to perform diagnostic studies of the effects of terrain and vegetation on local winds. ARL has also used a hydrostatic mesoscale forecast model (Battlescale Forecast Model B BFM) to produce tailored forecast products. In studies of the effectiveness of the BFM in producing low-level target area forecast products in complex terrain, the lack of low level forecast wind response to the true high resolution terrain became evident. As a consequence, research was initiated to integrate the HRW with the BFM to attain higher resolution meteorological forecasts for target areas and other localized areas on the battlefield. The northeast corner of San Francisco Bay area was selected as the common simulation domain because both BFM and HRW had already been run in previous studies there. The introduction of surface morphology features extends the high resolution analyses to the neighborhood scale. The BFM was initially run with a 5 km grid spacing over a 300 km x 300 km domain, but because of the difficulty of identifying the water=s shoreline with 5 km, the grid was changed to 2.5 km spacing over a 185km x 185 km domain. The HRW was run at 100m grid spacing over 5 km x 5 km. Level 1 DTED digitized terrain elevation data were already in-hand for HRW and BFM at the desired resolutions. Meteorological input data for BFM were obtained from the Navy=s NOGAPS model runs at 2.50 resolution, but when the BFM resolution was increased to 2.5 km it was necessary to use 10 NOGAPS data. Initially, meteorological input data for HRW were generated from the BFM simulations in the form of an equivalent upper air sounding and 10m meteorological surface station observation derived from a single BFM grid point and its vertical extension Acentered@ on the HRW domain. Subsequently, the surface data from the surrounding BFM grid points were added to the HRW run and later formed into an objective analysis. The new BFM-HRW simulations compared well with the solutions previously run for the San Francisco area. Each of these simulations were run with terrain elevation only. With the inclusion of digitized surface morphology into the high resolution code, further analysis was conducted to recover the high resolution interactions of the surface layer flow with the urban elements (in and about Rodeo, CA). The resultant neighborhood scale flow fields clearly exhibit far more variability that is related to feature location, type, and height than was produced from the terrain-only simulations. Examples of BFM-HRW simulations without and with morphological features are presented and the results of the coupled models are contrasted.
Session 11, Urban canopy layer: models
Thursday, 23 May 2002, 8:00 AM-1:30 PM
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