Author: Thomas E. CroleyPublisher:
ISBN:
Category : Evaporation (Meteorology)
Languages : en
Pages : 60
Book Description
Lake evaporation for the Laurentian Great Lakes is of the same order of magnitude as precipitation and runoff to the lakes and its estimation is important for simulations and forecasts of lake levels. Water or energy balance estimates of Great Lakes evaporation require storage-change data, not available in simulations or forecasts, and errors in the components of the balances are summed in the residual, giving large estimation errors for evaporation. Evaporation models, which use the aerodynamic equation with mass transfer coefficients developed originally in the Lake Hefner studies, were further developed for Lake Ontario during the International Field Year for the Great Lakes and adapted for other Great Lakes. Neither these models nor the balance models can be verified since independent estimates of evaporation are not available with sufficient accuracy. However, surface temperatures are available and can be used as verification data. The mass transfer coefficient research (where water surface temperatures must be known) is combined here with lumped model concepts of classical energy conservation and superposition heat storage to provide continuous simulation capability of both water surface temperatures and lake evaporation for use in outlooks and forecasts of lake levels. A new function is presented that uses a simple relation between surface temperature and heat stored in a lake based on current understandings of the thermal structure of large lakes. Calibration of the resulting model matches the water surface temperatures for those Great Lakes and small Lake St. Clair with satellite observations of water surface temperatures over the past 20 years. Evaporation and heat budgets over the annual cycle are presented for four of the Great Lakes and Lake St. Clair, and comparisons with long-term water balances are made.
