Properties of Circulation in Stratified Lakes

An approximate method is presented to display some features of wind-driven circulation in a stratified lake. Rotation of the earth is included, but the effects of bottom topography and shoreline configuration are ignored. The results indicate that the free surface slopes upward in the downwind direction and upward to the right of the wind (in the northern hemisphere) whereas the thermocline has the opposite slope. The free surface slope is of the order Δρ/ρ times the thermocline slope. The crosswind slope is of the order of one-fifth the downwind slope for lakes at about the latitude of the Great Lakes. These slopes decrease with increasing epilimnion thickness. The assumption of higher eddy viscosities also increases slopes, but decreases the velocities in the epilimnion. Decreased epilimnion velocities result from a smaller epilimnion thickness.