An air pollution model for complex terrain

Abstract

A dynamic air quality modeling system is presented for use in regions of complex terrain. It consists of two pre-processors and the air quality model. TERRAIN is the terrain analysis preprocessor. It accepts as input digitized terrain elevation data and analyses it in terms of the orientation and steepness of slopes. WIND is the second reprocessor, and based on the results of TERRAIN, determines the area in the region where the wind would be channeled or diverted. It produces a pair of wind matrices for the region of interest which give the horizontal and vertical shifts in direction respectively, at each point in the region at several vertical elevations. Each of the preprocessors are executed once for any particular region. The output from WIND is then read into DAMCT. DAMCT is a dynamic air quality model for regions of complex terrain. It accepts as input the matrics from WIND, a source emissions inventory for the region, and a sequence of meteorological conditions. It produces estimates of pollution concentrations at each point in the region at several vertical elevations over time. This data can then be processed by a general contour plotting program to give graphical displays of the concentration levels. This system is designed to be used for a mesoscale region, but can be applied to any size region be simply adjusting the grid size parameter. DAMCT can be run any number of times desired for a particular region after TERRAIN and WIND have been executed. The user can therefore modify the source inventory to reflect potential changes in the region and get an estimate of the effects. Any set up to 25 different meteorological conditions can be used, representing either typical conditions, or worst case conditions, as desired.

The system is intended to provide estimates of pollution concentration for the region of interest while still being relatively simple to execute from the user’s point of view. A user’s guide for each program is also given.