Elevation Change on the Greenland Ice Sheet at Qamanarssup Sermia, West Greenland

Repeat aircraft laser altimeter surveys carried out by NASA in 1993-1994 and 1998-1999 over the Greenland ice sheet revealed considerable thinning over large peripheral areas including the southwestern margin of the inland ice. This paper focuses on elevation changes on Qamanarssup sermia over the two decades prior to the NASA investigations. Qamanarssup sermia is an outlet glacier in the region around the Nuuk fiord, where interpolation of laser altimetry profiles indirectly revealed a thinning trend during the 1990s. The work presented here is a pilot study aimed at using historical data on elevation and ice extent for comparison with recent repeat laser altimetry. In particular, we use two aerophotogrammetrical surveys carried out in 1968 and 1985, respectively, from which detailed digital maps have been derived and utilized for determining elevation change. Terminus changes are also analyzed by comparing the two aerial photogrammetrical surveys with both a Landsat image and a terrestrial survey from 1980.