Surface heat fluxes from Lake Ontario: Further verification of lake thermal model

Abstract

The components of heat flux at the surface of Lake Ontario during the stratified season of 1972 are estimated using a lake thermal model, which has previously been verified with respect to temperature simulation. The model inputs are lake geometry and optical properties and surface weather observations. The heat flux components are compared with independent observationally based estimates. The net flux is simulated accurately by the model; the radiative input to the lake is significantly overestimated. The error in the radiative flux is traced to the expression accounting for the effect of cloud cover on insolation. This error leads to compensating errors in sensible and latent heat fluxes, resulting in accurate simulation of the net heat flux. Evaporation rates estimated by the model are approximately 50% higher than other estimates. The use of observed insolation, or a more accurate formula for the effect of clouds, would probably lead to accurate simulation of evaporation rates.