Differential cooling in lakes

We present the results of a project on differential cooling in lakes. This project aimed at quantifying the cross-shore convective circulation induced by differential cooling, also known as the thermal siphon (TS). Our case study was a small peri-alpine wind-sheltered lake (Rotsee, CH), where we studied the seasonal evolution of  TS over a year using a combination of field observations and high-resolution RANS and LES models. We found that TS  is a frequent cross-shore transport process which can be predicted using laboratory-based scaling formulae. We also observed that penetrative convection modifies the dynamics of the cross-shore flow, which has implications for the littoral-pelagic connectivity. In addition, we quantified the TS-induced lateral transport of dissolved gases, including oxygen and methane. We extended our findings to other lakes in order to improve the prediction of TS occurrence and intensity and we developed a procedure for predicting TS-induced transport based on factors such as lake bathymetry, meteorological forcing (including wind and cooling), and the vertical thermal structure of the lake.