Summer thermal structure and anticyclonic circulation of Lake Erie

In most thermally stratified lakes, the summer thermocline has the shape of a “dome”, with a shallower depth offshore than nearshore. This configuration is accompanied by a lake‐wide cyclonic circulation. Lake‐wide observations of subsurface temperature in central Lake Erie revealed an atypical “depressed” or “bowl‐shaped” thermocline in late summer, with a deeper thermocline in the middle of the lake and a shallower thermocline nearshore. Currents measured in the central basin when the bowl‐shaped thermocline was observed were anticyclonic, forming a single basin‐wide gyre. It is suggested that the unusual bowl‐shaped thermocline is the result of Ekman pumping driven by anticyclonic vorticity in surface winds. The bowl‐shaped thermocline can lead to greater hypoxia in bottom waters and negative effects on biota by reducing the hypolimnetic volume. Key Points Currents measured in the central basin were anticyclonic Bowl‐shaped thermocline is linked to Ekman pumping