HR: 0800h
AN: C41A-0170    [Abstracts]
TI: Changes in the 21st Century Arctic Freshwater Budget Simulated in a Multi-Member Ensemble with the Bergen Climate Model
AU: * Furevik, T
EM: tore@gfi.uib.no
AF: Geophysical Institute, University of Bergen, Allegt 70, Bergen, 5007 Norway
AU: * Furevik, T
EM: tore@gfi.uib.no
AF: Bjerknes Centre for Climate Research, Allegt 55, Bergen, 5007 Norway
AU: Bethke, I
EM: ingo@gfi.uib.no
AF: Geophysical Institute, University of Bergen, Allegt 70, Bergen, 5007 Norway
AU: Bethke, I
EM: ingo@gfi.uib.no
AF: Nansen Environmental and Remote Sensing Center, Thormollensgt 47, Bergen, 5007 Norway
AU: Drange, H
EM: helge@nersc.no
AF: Nansen Environmental and Remote Sensing Center, Thormollensgt 47, Bergen, 5007 Norway
AU: Drange, H
EM: helge@nersc.no
AF: Bjerknes Centre for Climate Research, Allegt 55, Bergen, 5007 Norway
AB: Complete mass, heat, and freshwater budgets have been calculated for all regions in the Arctic using output from a 300-year control integration with the Bergen Climate Model (BCM). Comparison with observation shows that the model reasonably well reproduces the observed sea-ice cover and oceanic circulation in the Arctic, although the sea-ice is in general too thin, and the mixed-layer too deep. Furthermore, the runoff, although based on a very simple scheme, is close to observations, both for the Russian rivers and for the Mackenzie River. Also the response to atmospheric forcing such as the Arctic Oscillation is realistic. An ensemble of 5 CMIP2 integrations, where the atmospheric concentration of CO2 is increased by 1% per year, has been performed and the results are compared to the control integration. Of particular interests for the freshwater budget are an almost total disappearance of the summer ice cover, an increased runoff in all major rivers, and an increased export of freshwater to the Nordic Seas and North Atlantic Ocean. Although there is a 10-12% reduction in the Atlantic meridional overturning circulation, there is actually a small increase in the Atlantic inflow to the Nordic Seas and via the Barents Sea to the Arctic Ocean. This may at least partly be attributed to increased westerlies (deeper Icelandic low) in the model simulations.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4207 Arctic and Antarctic oceanography
DE: 1655 Water cycles (1836)
DE: 1836 Hydrologic budget (1655)
DE: 1860 Runoff and streamflow
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting