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A Numerical Simulation of Local Winds and Photochemical Air Pollution (I): Two-Dimensional Land and Sea Breeze

1983; The Meteorological Society of Japan; Volume: 61; Issue: 6 Linguagem: Inglês

10.2151/jmsj1965.61.6_862

2186-9057

Fujio Kimura,

Atmospheric Ozone and Climate

Numerical simulations of photochemical air pollution under a theoretical two-dimen-sional local wind system are carried out in order to clarify the fundamental characteristics of the effects of local wind upon photochemical air pollution. The numerical model used here is divided into two steps. The first step is a local wind model which is constructed from the Boussinesq approximation and the hydrostatic equation, and the second step is a photochemical air pollution model in which concentrations of pollutants are calculated using the results of step one as the meteorological data. In the second step, the photo-chemical reaction system, which is actually very complex, is extremely simplified by a parameterization technique. Although this parameterized reaction model is simple, its results, especially the fundamental behaviors of the ozone concentration, are very close to the actual reaction system.The following results were found: 1) In the source area, the diurnal variation of the O3 concentration has a large peak at about noon, but the concentration of NOx has a bi-modal variation with two peaks, one in the morning and another in the evening; 2) The time of the maximum ozone concentration becomes later with an increase in distance from the source area which is located near the coast; 3) At night, a large amount of ozone still remains in the upper layer near the source area, but the concentration is very low near the surface; 4) The large-scale wind affects the distributions of pollutants, even if it is mild. Particularly, it strongly affects the remaining concentrations of pollutants which were formed on the previous day; 5) A mountain inland acts as a suction pump which transports the pollutants from the plain to the upper layer over the mountain.