Dispersion of Floatables in Lake Currents

Abstract

A group of ten sub-surface drogues were released in a cluster in the epilimnion 15 km offshore near Oshawa, Lake Ontario, and the subsequent drift and horizontal spread were followed for 72 h using the radar/decca navigation system of the Canadian Survey Ship Limnos. Experimental data suggest periodic shrinking and expansion of the drogue group at approximately 16–18 h corresponding to the local inertial period. This is attributed to the generation of convergence and divergence flow fields as the inertial currents are modified by the sloping shore line or a sloping thermocline. Thus, mesoscale motions such as convergence and divergence of the flow field as well as turbulent dispersion due to random eddies are important considerations in the kinematics of floatables.