Monitoring Greenland ice sheet’s climate and exploring Moulins (Invited)

The Greenland Climate Network (GC-Net) was established in spring 1995 with the intention of monitoring climatological and glaciological parameters at various locations on the ice sheet over several decades. The GC-Net currently consists of 18 automatic weather stations distributed over the entire Greenland ice sheet: (a) along the crest of the ice sheet (2500 to 3200 m elevation range) in a north-south direction; (b) close to the 2000 m contour line (1830 m to 2500 m); (c) in the ablation region (50 m to 800 m); and (d) at the equilibrium line altitude at the west coast and in the north. Each automatic weather station is equipped with meteorological and glaciological instruments to monitor important climate parameters which are transmitted on an hourly basis via satellite links. A climatological summary (1995-2009) for a number of stations will be presented indicating the temperature increase of up to 2 deg. C per decade along the west coast of Greenland, reduction of surface albedo values along the equilibrium line altitude, increase in ablation region and ice loss close to the margin of the ice sheet, interannual variability of solid precipitation and radiation field. For example, the radiation has been monitored continuously at Swiss Camp since 1993. The time series of mean monthly net radiation values shows the highest values in the mid 90’s, variability with time, whereas the surface albedo shows a marked increase from 2000 to present. Increase in ice velocity in the ablation region and the concurrent increase in melt water suggests that water penetrates to great depth through moulins and cracks, lubricating the bottom of the ice sheet. New insight was gained of subsurface hydrologic channels and cavities using new instrumentation and a video system during the melt peak in August 2007. Volume and geometry of a 100 m deep moulin were mapped with a rotating laser, and photographs with digital cameras. Sub-glacial hydrologic channels were investigated and filmed using a tethered, autonomous system, several hundred meters into the ice. These new results will be discussed in view of the rapid increase in melt area and mass loss of the Greenland ice sheet due to increasing air temperatures. New insight was gained of subsurface hydrologic channels and cavities using new instrumentation and a video system during the melt peak in August 2006-2009. Volume and geometry of a 100 m deep moulin were mapped with a rotating laser, and photographs with digital cameras. Sub-glacial hydrologic channels were investigated and filmed using a tethered, autonomous system, several hundred meters into the ice. These new results will be discussed in view of the rapid increase in melt area and mass loss of the Greenland ice sheet due to increasing air temperatures.