Evaporation from the surface of the Arctic Tundra on Axel Heiberg Island

Abstract

Hourly and daily evaporation rates were measured at the base camp (79°25′N, 90°45′W, 200 m above mean sea level) as part of the energy balance program during the Axel Heibergy Island Expedition in spring and summer of 1969, 1970, and 1972. The study period covered about 50 days of the dry snow period, 15 days of the melt period, and 2 months of the postmelt period in each year. The measuring and analysis methods are described, in that the aerodynamic profile method is examined, objective criteria are developed to accept or reject the profile data for the Bowen ratio energy balance method, and the problems of the snow lysimeter and the ordinary weighing lysimeter are described. Systematic differences among these methods are presented, and the causes for the differences are examined. Seasonal and diurnal variations of the evaporation rate are discussed. A unique effect of the föhn on evaporation is found and the cause investigated. Each season, characterized by different surface conditions, is found to possess a rather distinctive evaporation rate and ratio of latent heat flux to net radiation. The annual total evaporation is estimated at 140 mm, which is equivalent to 80% of the annual total precipitation, the remaining 20% being annual total runoff. The runoff occurs mostly during and immediately after the melt of the snow cover.