Initial field observations on Qaanaaq ice cap, northwestern Greenland

Abstract

To study the glaciological processes controlling the mass budget of Greenland's peripheral glaciers and ice caps, field measurements were carried out on Qaanaaq ice cap, a 20 km long ice cap in northwestern Greenland. In the summer of 2012, we measured surface melt rate, ice flow velocity and ice thickness along a survey route spanning the ice margin (200 m a.s.l.) to the ice-cap summit (1110 m a.s.l.). Melt rates in the ablation area were clearly influenced by dark materials covering the ice surface, where degree-day factors varied from 5.44 mm w.e. K -1 d -1 on a clean surface to 8.26 mm w.e. K -1 d -1 in the dark regions. Ice velocity showed diurnal variations, indicating the presence of surface-meltwater induced basal sliding. Mean ice thickness along the survey route was 120 m, with a maximum thickness of 165 m. Ice velocity and temperature fields were computed using a thermomechanically coupled numerical glacier model. Modelled ice temperature, obtained by imposing estimated annual mean air temperature as the surface boundary condition, was substantially lower than implied by the observed ice velocity. This result suggests that the ice dynamics and thermodynamics of the ice cap are significantly influenced by heat transfer from meltwater and changing ice geometry.

Surface elevation changes during 2007–13 on Bowdoin and Tugto Glaciers, northwestern Greenland

“…The mean annual temperature in the region is −8°C at sea level (Sugiyama and others, 2014). Bowdoin Fjord is typically covered with sea ice until early July.…”

Light-absorbing snow impurity concentrations measured on Northwest Greenland ice sheet in 2011 and 2012

“…Aokiet al,(2013)foundthatforcryoconite,theimaginarypartof the refractive index, which represents the light absorption by the material, is higher than the usual mineral dust from the spectral albedo measurements on the Qaanaaq Ice Cap. On the same Qaanaaq Ice Cap, themeltratesintheablationareawereinfluencedclearly by dark organic materials covering the ice surface (Sugiyama et al, 2014). Thus, dust is important in modulatingthealbedoinablationareasthroughmicrobial activities.…”

Observations and modelling of algal growth on a snowpack in northwest Greenland

“…The Qaanaaq Ice Cap, which lies on a small peninsula of north west Greenland, covers an area of 286 km2 and has an elevation of 5 approximately 1,110 m a.s.l. (Takeuchi et al, 2014;Sugiyama et al, 2014). We selected two study sites at different elevations (Sites-A and B) on the Qaanaaq Glacier, which is an outlet glacier of the ice cap and is easily accessible on foot from Qaanaaq village.…”

“…The temperature sensor and pyranometer of the AWS were placed at heights of 3.0 m and 2.5 m above the snow surface, respectively. Air temperature at Site-A was calculated from the air temperature 15 collected at Site-B with a temperature lapse rate, which was assumed as -7.80 × 10 -3 K m -1 (Sugiyama et al, 2014). Solar radiation at Site-A was measured hourly from day 172 (21 June 2014) to 214 (2 August 2014) with a pyranometer (EKO ML-020) installed at 1.5 m above the snow surface.…”