LAKE WATER TEMPERATURE SIMULATION-MODEL

Functional relationships to describe surface wind mixing, vertical tur bulent diffusion, convective heat transfer, and radiation penetration based on data from lakes in Minnesota have been developed. These relat ionships have been introduced by regressing model parameters found eit her by analysis of field data or by calibration (minimizing the differ ence between measured and predicted temperatures) in simulations on in dividual lakes, against gross lake properties such as surface area or Secchi depth. Results of the deterministic lake water temperature stra tification model using the functional relationships are not much diffe rent than results using the individual calibrations on a great variety of lake surface areas, depths, and transparencies. The model also req uires no on-lake weather but uses input from existing off-lake weather stations. First order uncertainty analysis showed moderate sensitivit y of simulated lake water temperatures to model coefficients. The nume rical model which can be used without calibration has an average 1.1-d egrees-C root mean square error, and 93% of measured lake water temper atures variability is explained by the numerical simulations, over wid e ranges of lake morphometries, trophic levels, and meteorological con ditions.