HR: 15:00h
AN: U33B-05    [Abstracts]
TI: Arctic Fresh Water Export and its Impact on Climate in the 20th and 21st Century
AU: * Koenigk, T
EM: kahl@dkrz.de
AF: Max-Planck-Institute for Meteorology, Bundesstrasse 53, Hamburg, 20146 Germany
AU: Mikolajewicz, U
EM: mikolajewicz@dkrz.de
AF: Max-Planck-Institute for Meteorology, Bundesstrasse 53, Hamburg, 20146 Germany
AU: Haak, H
EM: haak@dkrz.de
AF: Max-Planck-Institute for Meteorology, Bundesstrasse 53, Hamburg, 20146 Germany
AU: Jungclaus, J
EM: jungclaus@dkrz.de
AF: Max-Planck-Institute for Meteorology, Bundesstrasse 53, Hamburg, 20146 Germany
AB: Coupled IPCC experiments with the Max-Planck-Institute climate model ECHAM5/MPI-OM are used to analyse the changes in the fresh water export out of the Arctic. Furthermore, the impacts of these changes on climate are investigated. In the 20th century, 57 % of the simulated Arctic fresh water export (reference salinity is 34.8) into the North Atlantic Ocean takes place through Fram Strait, 32 % through the Canadian Archipelago and 11 % over the Barents Shelf. The variability is mainly governed by the ice export through Fram Strait and is highly affected by the atmospheric circulation. Large ice exports provoke a dramatic reduction in Labrador Sea surface salinity in the following years. Oceanic convection is decreased and ice cover is increased. As a consequence, the heat flux from ocean to atmosphere is below normal, which leads to significant negative temperature anomalies in the Labrador Sea. In the 21st century, our model results show a reduction of sea ice volume and an increase of precipitation and Arctic rivers runoff. Most of this additional fresh water is stored in the Arctic Ocean. The total Arctic fresh water export is only slightly changing until year 2100. However, a redistribution of the export occurs: The solid part becomes much smaller with time and plays no significant role anymore at the end of the 21st century. At the same time the fluid part increases. The export through the Canadian Archipelago rises by 0.025 Sverdrup, while the export over the Barents Shelf is reduced by 0.02 Sverdrup. The amount of fresh water exported through Fram Strait stays constant but the interannual variability is decreased by 25 %. The impact of the export through Fram Strait on Labrador Sea climate is thus strongly reduced. In contrast, the export through the Canadian Archipelago gains importance. The convection is reduced by about 40 % in the Greenland Sea and 60 % in the Labrador Sea. The reduction in the Labrador Sea can be explained by increased fresh water export through the Canadian Archipelago. In the Greenland Sea higher air and sea temperatures are the main reason for the decrease. In both regions the difference of precipitation and evaporation becomes larger and contributes to the decrease in convection. The meridional overturning circulation (MOC) at 30 degrees N declines from about 22 Sverdrup in the 20th century to 16 Sverdrup at the end of the 21st century. The reduction in the MOC leads to a much weaker warming in the northern North Atlantic in comparison to the surrounding areas.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1621 Cryospheric change (0776)
DE: 1626 Global climate models (3337, 4928)
DE: 1655 Water cycles (1836)
SC: Union [U]
MN: Fall Meeting 2005