Variation in Lake Water Temperature in the Nanticoke Region of Long Point Bay, Lake Erie, during the Open-Water Season

Abstract

Lake water temperature on the north shore of Long Point Bay near Nanticoke (Lake Erie) over the years 1971–83 varied considerably during the lake warming cycle. Upwellings, resulting in temperature drops of 5–10°C over a 2–3 d period, were common from mid-May to mid-August. Warmer surface waters returned within 6 d (usually 3 d) following summer upwellings. In spring, the recovery times were variable but typically lasted longer, up to 25 d. Temperature fluctuations that exceeded 5°C but lasted less than 48 h were also frequent during the lake warming cycle. The progressive deepening of the epilimnion to the 12-m depth of Long Point Bay and the associated increase in the heat content of the Bay resulted in a stable temperature regime by mid-August. Diurnal heating and cooling of surface waters, by as much as 4°C, was apparent under calm conditions. Mean April–November temperatures varied by more than 2°C, reflecting annual variation in atmospheric warming.