INVESTIGATION OF TURBULENT MIXING IN SHALLOW LAKES USING TEMPERATURE MICROSTRUCTURE MEASUREMENTS

A microstructure profiler was designed especially for the investigatio n of the diurnal dynamics of turbulent mixing in shallow lakes. 7 hour s observation of these dynamics in a shallow, polymictic lake shows a multitude of different mixing processes acting together on very short time-scales. Estimated turbulent diffusivities for the surface mixed l ayer, using the Cox number method, are lognormally distributed with a mean of K-z approximate to 10(-5) m(2) s(-1). The results are discusse d within the context of their relevance for modelling the effect of tu rbulent mixing on phytoplankton primary production.