Atmospheric transport and diffusion at coastal sites

On the average overland atmospheric diffusion rates are shown to be three times more rapid than those with overwater trajectories when the water is colder than the air temperatures over the land. The transport distance required to complete the transition from overwater to overland diffusion is shown to be a function of plume height, wind speed, and vertical temperature profile. Diffusion models are suggested to account for the diffusion rates within this transition zone. Coastline atmospheric trajectories are discussed in terms of local effects which result in the daily reversals between land and sea breezes and of large-scale pressure gradient effects which generally result in straight-line trajectories. (author)