Surface flow velocity on Qaanaaq ice cap, Greenland in July 2013

The surface motion of the glacier was measured by surveying 5 stakes (1.5-2.0 m long aluminium poles) installed in the ice at Qaanaaq ice cap. We used dual-frequency GPS receivers and antennas (GNSS GEM-1) to measure the three-dimensional positions of the stakes. One antenna was fixed on the roof of Qaanaaq Club House as a reference station. At Q1203, the antennae were mounted on the stakes and operated every seconds. The stakes at Q1201-Q1205 except for Q1203 were surveyed with the same devices for 30 minutes. These data were processed in static mode by the GPS software (RTKLIB) to compute the position of the stakes every 30 minutes. Measurement errors were estimated below 10 mm.