Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pakitsoq, West Greenland

• Main Authors: Braithwaite, R. J., Laternser, M., Pfeffer, W. T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1994
• Subjects: Greenland; Ice Sheet; Journal of Glaciology
• Online Access: https://research.manchester.ac.uk/en/publications/23ca5227-ca91-430f-b43f-f5c57893e18a

Firn-density variations have been studied in the lower accumulation area of the Greenland ice sheet (1440-1620 m a.s.l.) near Pakitsoq, West Greenland. The main control on density in the near-surface firn layer (of 5-10 m thickness) is the formation of ice layers by the refreezing of meltwater that reaches depths of 2-4 m below the surface. The density variations are described by the ratio of annual surface melt M to the annual accumulation C. The ratio M/C is about 0.6 at the run-off limit (at about 1400 m a.s.l. in the study area) where refreezing of meltwater transforms snow into impermeable ice. The mean density of near-surface firn decreases with elevation, reflecting a decrease in melt with elevation. A 1978-85 thickening of the ice sheet has been observed by satellite-radar altimetry. Near-surface firn density is very sensitive to climate change and might be an attractive target for climate monitoring. -from Authors