On the Net Cyclonic Circulation in Large Stratified Lakes*

Schwab et al. have investigated a possible cause of long-term cyclonic circulation often observed in stratified lakes. They conclude that the adiabatic boundary condition applied to the bottom boundary leads to cyclonic circulation. In this note the authors emphasize that it is the combination of vertical mixing of density, the associated bottom and surface boundary conditions, and variable bottom topography that is important. The authors demonstrate the mechanism using a numerical model. Results also demonstrate the important role of the cross-shore flow (driven by vertical mixing of momentum) in setting the maximum azimuthal flow speed and the cross-shore structure of the azimuthal flow.