Relative Effects of Terrain and Morphology Complexities upon very local Airflow and Diffusion

In order to improve the present application of mesometeorological modeling to field application problems, a higher resolution, micrometeorological analysis could provide a more local and relevant set of meteorological conditions which are directly affected by forested areas and adjacent communities. As a result of the increased resolution, i.e. 100m (40 to 400m) the morphology of land features can now contribute to part of the underlying surface’s interaction with the boundary layer of the atmosphere. For analyses with computational grids of 100m in x and y, morphological features such as vegetation, structures, and simple surfaces can be more important than nominal changes in terrain elevation over the 100m grid. There are, of course, those cases where terrain interactions will dominate over morphological interactions. USARL’s high resolution wind model with canopy effects (vegetation as well as urban) is applied to several non-homogeneous, terrain-morphology scenarios to simulate finer variations in the resultant very local flow fields. The intent is not to replace mesoscale analyses, but rather to eventually augment and enhance their coarser analysis with finer details that reflect locally-influenced changes in flow fields as well as the behavior of aerosol dispersion. Example solutions are given for complex terrain and again for the added presence of morphological features upon these same flow fields. The wind fields are then prepared to drive a diffusion code to produce the downwind behavior of puffs and plumes on the same very local scale. The resultant wind fields show that notable differences between the terrain-morphology influenced simulations versus the terrain-only influenced wind fields can be simulated with a micro-alpha model/code. These differences, of course, are seen also in the resultant diffusion analyses. Our follow-on research has shown that this microscale code with its all terrain approach (complex, vegetated, urbanized) has been successfully coupled with our mesoscale analysis capability. These results can be beneficial to a variety of applications addressing agriculture, forests, HAZMAT, air quality, homeland security and more.