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Languages : en
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Book Description
A three-dimensional numerical model previously developed to simulate an airflow over complex terrain has been extended to simulate a pollutant dispersion over the same topographic condition. This study is limited to an advective case, i.e., modification of the inflow concentration profile by the air motion greatly disturbed by the underlying topograpy. The pollutant is considered to be passive and nonreactive. Emissions of pollutants are not considered, but pollutant deposition at the surface is included. Dilution of pollutants due to the vertical motion resulting from divergence and convergence of the horizontal wind over the rugged terrain is an item of major interest. A pollutant advected through the inflow boundary experiences the greatest reduction in concentration (by approximately 50%) in the region directly above the downslope of the mountain. This is mainly due to mixing with clean air which is transported downward by subsidence. concentration in the surface layer downwind of the mountain is considerably greater for the unstable case than for the stable case. This is due to the fact that higher concentrations in the layer directly above have been transported downward by turbulent mixing. Thus, fumigation appears to be properly simulated. The model is being modified to include solar radiation in order to produce diurnal variations of the airflow. It is intended to test the simulation against observations in the near future.
