The Effect of Weather Variability on the Energy Balance of a Lake in the Hudson Bay Lowlands, Canada

Abstract

Evaporation is an important component of the water balance of lakes in the Hudson Bay Lowlands, but the amount of summer evaporation in this area is not well known. Hourly summertime estimates of evaporation, from a small tundra lake near Churchill, Manitoba, are compared to equilibrium evaporation estimates of the Penman model. For the entire measurement period .alpha. = 1.35. For individual days .alpha. ranges from 1.0 to 2.0 and for individual hours from 1.0 to 4.0. Local advection is primarily responsible for the large fluxes of latent heat. The latent heat flux exceeds available radiant energy over the summer, with temperature inversions occurring over the lake on the majority of days. The advective enhancement of lake evaporation responds to daily weather variations. The classification of these variations will improve operational estimates of lake evaporation.