The evolution of the englacial temperature distribution in the superimposed ice zone of a polar ice cap during a summer season

Abstract

The aim of the present investigation was to provide more insight into the processes affecting the evolution of the englacial temperature distribution at a non-temperate location on a glacier. Measurements were made in the top 10 m of the ice at the summit of Laika Ice Cap (Canadian Arctic) during the summer 1975 (by Blatter et al.). This location is in the superimposed ice zone. The model simulation includes calculation of the surface energy fluxes, of radiation penetration, of the englacial temperature and density distribution, and of the formation, penetration and refreezing of melt water. In the first kind of experiments the energy fluxes from the atmosphere were tuned in such a way as to obtain the right amount of ablation. With these energy fluxes as a boundary condition the consequences of melt water penetration and refreezing for the englacial temperature distribution were proofed to be considerable. In the second kind of experiments the measured temperature at the interannual surface was used as boundary condition, and to start with the temperature below the interannual surface could only be affected by conduction. The measured and the calculated temperatures match until melt water penetrates to the interannual surface. Thereafter, calculations give too low temperatures. Most of this energy deficiency will probably be due to radiation penetration, whereas a minor part of it may be caused by melt water penetration into open veins or an error in the assumed interface temperature.