Remote sensing of supraglacial lakes on the Greenland Ice Sheet.

The dynamic mass loss from the Greenland Ice Sheet has prompted considerable research into the role of supraglacial lakes in causing dynamic thinning. These lakes can drain through 1000 m of ice to the bed and are thought to play an important role in connecting the surface and basal hydrologies of the ice sheet, allowing water to reach the bed and cause the ice to accelerate. Despite this apparent importance little research has been carried out on lakes outside of SVV Greenland, and no research has examined the occurrence of lake drainage over the whole of Greenland. The aim of this thesis is to discover where lakes occur for the entire Greenland ice Sheet, and how these lakes drain. New remote sensing techniques for monitoring lakes through the melt season were developed and tested. The evolution of 2600 lakes (those lakes larger than > 0.125 km2) was studied over five years (2005-2009) using 3704 MODIS images. Lakes were discovered to either drain fast to the bed, more slowly over the surface, or to freeze at the end of the melt season. There were 263 fast lake drainages per year of which 61% were in the SW region and a further 17% in the NE, both regions where mass loss is mainly due to surface mass balance. In the dynamically thinning SE region there were only three fast lake drainages per year along a 1300 km coastline. In the NW, fast lake drainage did not occur on five of the ten glaciers with the most rapid dynamic thinning. The results of this thesis show that the drainage of supraglacial lakes cannot have been responsible for dynamic mass loss from the Greenland Ice Sheet