Jakobshavn Glacier, West Greenland: 30 years of spaceborne observations

Abstract. Early 1960's reconnaissance satellite images are compared to more recent image and map data in an inter-annual and seasonal study of West Central Greenland margin fluctuations. From 1962 to 1992, ice sheet margins to the north and south of Jakobshavn Glacier retreated despite a decline in average summer temperatures. The retreat may be reversing along the southern flank of the ice stream where regional mass balance estimates are positive. From 1950 to starting point. A portion of the 1962 image (37.5 km x 37.5 km) taken on May 17, 1962 (Figure l(a)) shows the calving margin of Jakobshavn Glacier, one of the world's fastest moving glaciers reaching speeds up to 7 kin/year near the calving front [lken et al., 1993]. Figure 1 also includes subsequent, similar images acquired by aerial photography on July 10, 1985 (Figure l(b)), by the SPOT (System Pour IObservation de la Terre) visible imaging satellite on May 30, 1988 (Figure l(c)) and by the 1996, the terminus of Jakobshavn Glacier seasonally European Space Agency's SAR (Synthetic Aperture Radar) fluctuated-2.5 km around its annual mean position. The total calving flux during the summer is more than six times that during winter. We identified that summer melting and the break-up of sea ice and icebergs in the fjord are important in controlling the rate of iceberg production. If correct, calving rates may be expected to increase should climate become warmer in the near future