Horizontal dispersion in the surface layer of a long narrow lake

Dye tracer experiments were conducted in the surface layer of Kootenay Lake, British Columbia. Estimates of the coefficient of horizontal diffusivity range from 0.01 to 13 m2 s–1. In some instances the diffusion rate increased more rapidly as a function of scale than expected based on empirical generalizations from the oceans and smaller lakes. The experiments illustrate the role of shear dispersion and internal waves. Key words: lake dispersion, stratification, dye tracing, turbulent diffusion, mixing, wind stress.