Abstract
Firn temperatures and meltwater refreezing are studied in the lower accumulation area of the Greenland ice sheet as part of an international project on sea level changes. In the study area, 1440–1620 m a.s.l., meltwater penetrates several metres into the firn and refreezes, warming the firn by 5–7°C compared with annual air temperatures. This firn warming is closely related to surface melt which can be estimated by several methods. A relatively high degree-day factor is needed to account for the melt rates found.
Highlights
The field area is above Påkitsoq, east of Ilulissat (Fig. 1), where GGU has measured mass-balance in the ablation area since 1982 (Thomsen et al, 1989)
The above discussion applies to the maximum depth of meltwater penetration as some meltwater may be retained in pore spaces and only refrozen in the folIowing winter
Further meltwater fills up the pore spaces and percolates deeper into the fim when the residual water content is exceeded (Colbeck, 1976), or runs off if it meets an impermeable surface at the melting point
Summary
The field area is above Påkitsoq, east of Ilulissat (Fig. 1), where GGU has measured mass-balance in the ablation area since 1982 (Thomsen et al, 1989). A reconnaissance for the EPOCH project was made in August 1990 and field work was carried out in May and August of 1991 and 1992 respectively. The data only cover three years but temperature data from Ilulissat (formerly Jakobshavn) show that summer 1990 was relatively warm, summer 1991 was average and summer 1992 was very cold (Table 1). Annual mean temperatures were low in all three years. The field data must be interpreted against this background of longer term temperature variations. Accumulation stakes for the EPOCH project extend from the 'Swiss Camp' at 1160 m a.s.l. to 1620 m a.s.l. well within the accumulation area. The surface features observed in August 1990 (Fig. 2) have hardly been seen
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