HR: 08:45h
AN: C21C-04 INVITED    [Abstracts]
TI: Continued thinning of sea ice at the North Pole and in the Transpolar Drift?
AU: * Haas, C
EM: Christian.Haas@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Bussestrasse 24, Bremerhaven, 27570, Germany
AU: * Haas, C
EM: Christian.Haas@awi.de
AF: University of Alberta Department of Earth and Atmospheric Sciences, 1-26 Earth Sciences Building University of Alberta, Edmonton, AB T6G2E3, Canada
AU: Etienne, J
AF: Septieme Continent, 11, rue Caulaincourt, Paris, 75018, France
AB: The extent of Arctic sea ice is strongly decreasing, with a new record summer minimum observed in 2007. However, the interpretation of this rapid decline in the context of climate change is hampered by the lack of ice thickness data, as it is unclear how much of the retreat is due to variations in thermodynamic or dynamic boundary conditions. A 350 km long ice thickness profile was obtained in April 2007 between the North Pole and 87N, 58W by means of helicopter-borne electromagnetic profiling. The measurements revealed the presence of predominantly second-year ice with a mean total (snow plus ice) thickness of 3.31 +/- 1.51 m and a modal total thickness of 2.35 m. There was no strong ice thickness trend towards the coast of Ellesmere Island. Ground-based measurements showed a bi-modal snow thickness distribution, with 0.05 m of snow on first-year ice and 0.2 to 0.4 m on second-year ice. If compared with earlier sporadic measurements in the same region between 1991 and 2001, the results indicate a continued ice thinning of 0.3 to 0.7 m between 2001 and 2007. However, the comparison is complicated by the unknown amplitude of the seasonal thickness cycle, as previous measurements were only performed during August. Therefore, the paper discusses the use of additional data like e.g. from ice mass balance buoys which can give insights into the thermodynamic components of sea ice mass balance, and outlines the urgent need for more systematic snow and ice thickness observations. This need has unfortunately only barely been met so far during the ongoing International Polar Year. The paper will also present plans for future, more systematic airborne campaigns, which could cover the whole region of the Arctic Ocean. These include an Arctic airship crossing of the Total Pole Airship project, and an Arctic circumnavigation with a new, German BT67 airplane.
UR: http://www.jeanlouisetienne.fr/poleairship
DE: 0750 Sea ice (4540)
DE: 0762 Mass balance (1218, 1223)
DE: 0766 Thermodynamics (1011, 3611, 8411)
SC: Cryosphere [C]
MN: 2007 Fall Meeting