Abstract
It is well known that soluble substances are influenced by the presence of fog through dissolution into fog droplets and subsequent aqueous phase reactions. However changes in the thermal structure due to the presence of fog may also affect the physical behavior of atmospheric pollutants through changes in the turbulent diffusion capability.
In this study, we investigated the influence of fog on the deposition of atmospheric pollutants to the ground surface by means of numerical simulations, which were composed of a meteorological model, a deposition model, and an aqueous phase chemical model. Target period was night time when fog formed frequently. The main results obtained are as follows.
(1) It was recognized that the atmospheric condition of layering was destabilized in the fog layer and stabilized just above the fog layer when it formed.
(2) The amount of deposition of even insoluble and inactive substances to the ground increased when fog was present owing to changes in the thermal structure.
(3) The amount of total sulfur deposition also increased when fog was present. Especially that of total sulfate deposition increased significantly by effects such as dissolution and aqueous phase chemical reactions and changes in the thermal structure.
The results suggest that we should take into account the deposition of fog droplets and the effect of changes in thermal structure of the atmosphere in the presence of fog when we calculate the amount of deposition of atmospheric polllutants.
