31 אוקטובר, 2022
Air-water interactions regulate lake-water temperature by balancing the rate of change of water temperature (stored heat) with the incoming and outgoing heat fluxes, which are functions of water temperature and external forcing. Yet, there is a large knowledge gap in quantifying the thermoregulation of a lake, and especially managed lakes. The thermoregulation of a restored and managed Mediterranean lake (Agamon Hula, Israel) was first, explored by direct measurements of all major heat fluxes. Then, a rigorous analysis revealed how water temperature of a lake shifts toward a steady state, scaled by the lake's response time. The analysis improves current theoretical knowledge. The analysis indicates that the steady-state temperature is controlled by external environmental forcing and not by lake depth. Whereas the thermal response time to re-attain a steady state, following an abrupt change in various environmental conditions, is controlled by water depth. Lake-temperature response to an oscillating environmental forcing revealed that both the amplitude of water temperature fluctuations and the time delay from the steady-state are controlled by the ratio between the environmental forcing’s time period (diurnal, seasonal or other cycles) and the thermal response time of the lake.