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.