Dynamics of large tidewater glaciers in East Greenland: recent results from satellite remote sensing and a field GPS campaign Abstract

abstract

  • Histories of ice velocity and calving front position of five outlet glaciers in East Greenland are reconstructed from field measurements, aerial photography, and satellite imagery, and show a north-south gradient in glacier response to external forcings. The northern three glaciers, located in Scoresby Sund (Daugaard-Jensen, Vestfjord, and Graah glaciers), have not undergone any substantial change in flow speed or terminus position over the last few decades. Kangerdlugssuaq and Helheim glaciers, located approximately 400-500 km south of Scoresby Sund, appear to have undergone a series of substantial changes in the last ~2 years, including a 40-300% acceleration in flow speeds, widespread glacier thinning, and rapid retreat of the calving fronts. We mapped ice flow patterns for 2001 for all five glaciers by applying a feature tracking technique to sequential high-resolution visible imagery (either ASTER or Landsat ETM+). Modern velocities were determined from repeat high-precision differential GPS surveys conducted in June/July 2005. Each glacier was surveyed several times at five to twelve locations along its trunk, over a two-five day time span. GPS surveys from July 2005 indicate that Kangerdlugssuaq Glacier accelerated to ~14 km/yr (from 5 km/yr in 2001) within 1 km of the terminus. Helheim Glacier is now flowing faster than 11 km/yr (up from 6 km/yr in 2001) near the terminus and approximately 10 km/yr at a site ~5 km upglacier. Measuring flow speeds on glaciers moving on the order of 2 m/hr (hour!) presents a unique series of logistical and technical challenges which we will discuss in our presentation.

publication date

  • 2006

presented at event