A GUST-FACTOR CRITERION FOR RAPID DETERMINATION OF ATMOSPHERIC STABILITY AND MIXING HEIGHT FOR OVERWATER DISPERSION ESTIMATES

摘要

In order to estimate atmospheric pollution concentration downwind from its source, meteorological models (numerical, analytical, or graphical) are usually employed. Included in the model inputs are atmospheric stability and mixing height, which are not routinely measured in the marine environment. On the basis of relationships amongst gust factor, turbulence intensity, and stability parameter, methods are developed for rapid estimation of these two inputs. It is found that, based on the stability classification of the Offshore and Coastal Dispersion Model, when the gust factor (G, which is the ratio of peak gust to the sustained wind speed) is between 1.15 and 1.45, the stability is near-neutral. When G is less than 1.15, it is stable, and for G greater than 1.45, unstable. Using routine buoy measurements as a composite characteristic, equations for the mixing height under various stability classes are also formulated.