EFFECTS OF WIND DIRECTIONAL FLUCTUATIONS ON GAS-DIFFUSION OVER A MODEL TERRAIN

Wind tunnel experiments were carried out to study the effects of wind directional fluctuations on gas diffusion, under a neutral stability c ondition, over terrain models using the overlapping method. Ground-lev el concentrations were measured under 3 conditions with standard devia tions of wind directional fluctuation, sigma(A), of 5 degrees, 10 degr ees and 20 degrees. From these experimental results, an attempt was ma de to reduce the general rule of the relation between sigma(A) and the maximum ground-level concentration, C-max, over a terrain. The verifi cation and limitation in the application of this rule are discussed. F urthermore, it is reported that large sigma(A) has a strong influence on the ground-level concentration patterns and so unexpected concentra tion patterns appear under some conditions. Copyright (C) 1996 Elsevie r Science Ltd