Lake Water Temperature Simulation Model

Abstract

Functional relationships to describe surface wind mixing, vertical turbulent diffusion, convective heat transfer, and radiation penetration based on data from lakes in Minnesota have been developed. These relationships have been introduced by regressing model parameters found either by analysis of field data or by calibration (minimizing the difference between measured and predicted temperatures) in simulations on individual lakes, against gross lake properties such as surface area or Secchi depth. Results of the deterministic lake water temperature stratification model using the functional relationships are not much different than results using the individual calibrations on a great variety of lake surface areas, depths, and transparencies. The model also requires no on‐lake weather but uses input from existing off‐lake weather stations. First order uncertainty analysis showed moderate sensitivity of simulated lake water temperatures to model coefficients. The numerical model which can be used without calibration has an average 1.1°C root mean square error, and 93% of measured lake water temperatures variability is explained by the numerical simulations, over wide ranges of lake morphometries, trophic levels, and meteorological conditions.