Measurements of Overwater Diffusion: The Separation of Relative Diffusion and Meander

Abstract

Data compiled from surface releases of SF6 gas in a purely overwater environment are used in an attempt to parameterize both relative and single-particle diffusion in the lateral direction. Relative diffusion is found to roughly segregate into two surface-layer stability classes for ranges to 10 km. Single-particle diffusion, often referred to as meander, is not found to be strongly related to surface-layer stability under neutral to stable conditions, but does correlate well with measured lateral wind direction variance. Taylor's ?near field? solution closely predicts the single-particle lateral diffusion for these data, suggesting that meander may be dominated by very large-scale coherent structures which maintain their identity over travel distances of many kilometers.