Abstract
A study was made of the characteristics of diffusion parameters which are closely related to the lateral diffusion of pollutants in the atmospheric surface layer. In general, lateral turbulence magnitude and its scale, which are both important parameters in diffusion process, can not adequately be explained by the similarity theory of Monin and Obukhov. In stable air, lateral turbulence magnitude δv depends on Richardson number Ri, while in unstable air the relation between δv/u* (u*: friction velocity) and Ri depends also on height above the ground surface. In addition, sampling duration is equally an important parameter related to turbulence magnitude. On the other hand, regarding turbulence scale, dimensionless spectral peak frequency (fm) v depends on Ri and height in stable air, while in unstable air peak wavelength (λm) v seems to be dependent on the depth of the convective layer zi. Using these relationships on turbulent magnitude and scale, we find that the ratio of lateral to vertical diffusivity Ky/Kz decreases with the increase of unstability in unstable air and in stable air this ratio increases with the increase of stability.
