InSAR observations of ice elevation and velocity fluctuations at the Flade Isblink ice cap, eastern North Greenland

Abstract

The 8500 km2 Flade Isblink ice cap (FIIC) (81°15′N, 15°0′W) is the largest ice cap in Greenland. We use repeat‐pass interferometric synthetic aperture radar (InSAR) techniques to investigate the form and flow of the FIIC. European Remote Sensing satellite (ERS‐1 and ERS‐2) data acquired in winter 1996 were used to form a 100 m resolution digital elevation model (DEM), which we constrained using Ice Cloud and Elevation satellite (ICESat) laser altimeter elevation measurements from 2007. This InSAR DEM was used to isolate the phase due to motion from seven ERS‐tandem (1 day) pairs of SAR scenes acquired between 15 August 1995 and 7 February 1996, to produce one wintertime and two summertime velocity maps. Five of the eight major outlet glaciers draining the FIIC are marine terminating, and two terminate at a lake margin. A maximum ice velocity of 581 m yr−1 was observed in mid‐August 1995. Six of the eight major outlet glaciers exhibit seasonal velocity variations between late summer and winter, and flow speeds vary by up to 20% over a 10 day period in August 1995. Our findings show that while marine terminating glaciers flow faster than land terminating glaciers, there is no simple relationship between glacier type and seasonality of ice motion.