Modelling hourly rates of lake evaporation

Abstract

Abstract. The paper presents the initial results of a field study of open water evaporation carried out on three small- to medium-sized lakes in Western and Northern Canada. Lake evaporation was measured directly using eddy covariance equipment; profiles of wind speed, air temperature and humidity were also obtained over the water surfaces. Observations were made as well over the upwind land surface. Relationships were developed between the hourly rates of lake evaporation and those significant parameters (wind speed, land-water temperature and humidity contrasts, and the downwind distance from shore). The result is a relatively simple versatile model for estimating the hourly lake evaporation rates. The model was tested using two independent datasets. Results show that the modelled evaporation follows the observed values very well; the model follows the diurnal trends and responds correctly to sudden changes in environmental conditions.