HR: 1340h
AN: G33B-1242    [Abstracts]
TI: Arctic Warming, Greenland Melt and Moulins
AU: * Steffen, K
EM: konrad.steffen@colorado.edu
AF: CIRES, University of Colorado at Boulder, Campus Box 216, Boulder, CO 80309-0216, United States
AU: Huff, R
EM: rhuff@cires.colorado.edu
AF: CIRES, University of Colorado at Boulder, Campus Box 216, Boulder, CO 80309-0216, United States
AU: Behar, A
EM: alberto.behar@jpl.nasa.gov
AF: Jet Propulsion Laboratory, Pasadena, Robotic Vehicles Group, Pasadena, CA 91109-8099, United States
AB: Air temperatures on the Greenland ice sheet have increased by 4 deg. C since 1991. The ice sheet melt area increased by 30% for the western part between 1979-2006, with record melt years in 1987, 1991, 1998, 2002, 2005, and possibly the most extreme melt year in 2007. The increasing trend in the total area of melting bare ice is unmistakable at 13% per year, significant at a probability of 0.99. Hence, the bare ice region, the wet snow region, and the equilibrium line altitude have moved further inland and resulting in increased melt water flux towards the coast. Warm and extended air temperatures are to blame for 1.5 m water equivalent surface reduction at the long-term equilibrium line altitude, 1100 m elevation at 70 deg. N during summer 2007. 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.
DE: 0700 CRYOSPHERE (4540)
DE: 0726 Ice sheets
DE: 0776 Glaciology (1621, 1827, 1863)
DE: 0933 Remote sensing
SC: Geodesy [G]
MN: 2007 Fall Meeting