These are perennial areas where the cold, strong winds blowing down the glacier from the interior ice sheet constantly remove surface snow exposing bare ice. The winds also cause the bare glacier ice to evaporate (technically to sublimate as no melting is involved).
Over time this loss of ice at the surface exposes deeper ice layers that have had an origin much further inland and at much higher elevations. As the chemical isotopes of oxygen contained within the frozen molecules of water are determined mostly by temperature and hence altitude, they can be used to locate the approximate origin of the ice, initially as snow, on the steadily rising inland ice sheet.
The isotope measurements made on samples collected by the expedition from the "blue" ice areas will be compared with various models of the flow of the glacier and these will assist with understanding its behaviour and how quickly and in what ways it may be responding to any climate changes.
This is the fourth of six articles by Professor Drewry. Click here for the next installment.
Posted by Tim Fright on June 20, 2007 6:03 PM