An atmospheric diffusion study on a local scale at a coastal site

This report describes a series of atmospheric dispersion experiments which were carried out during the summers of 1983 and 1984 at the coastal site of Montalto di Castro (Italy) in sea breeze conditions. Sulphur hexafluoride (SF6) was used as an atmospheric tracer, while the thermal and anemological characteristics of the lower layers of the atmosphere were measured by vertical sounding with tethersonde systems and pilot balloons. The results have been analyzed to obtain information on the atmospheric dispersion characteristics for a Gaussian diffusion model. Two effects were clearly evident from the data collected: 1. (a) reduced lateral dispersion during the warmest period of the day; 2. (b) vertical diffusion confined to within the developing Internal Boundary Layer (IBL).