HR: 0800h
AN: OS41A-0461    [Abstracts]
TI: Climate Shifts in an Arctic Fjord: Intense Seasonality through Cross-Shelf Exchange
AU: * Cottier, F
EM: fcott@sams.ac.uk
AF: Scottish Association for Marine Science, Dunstaffnage Marine Laboratory Oban, Argyll, PA37 1QA United Kingdom
AU: Tverberg, V
EM: vigdis@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromso, N-9296 Norway
AU: Svendsen, H
EM: svendsen@gfi.uib.no
AF: Geophysical Institute, University of Bergen Allegaten 70, Bergen, 5007 Norway
AU: Inall, M
EM: mei@sams.ac.uk
AF: Scottish Association for Marine Science, Dunstaffnage Marine Laboratory Oban, Argyll, PA37 1QA United Kingdom
AB: Debate over Arctic climate has focussed on the relative balance between Atlantic, Arctic and fresh water in a system. It is anticipated, and in many cases observed, that the magnitude of each of these sources will vary in time and location. Depending on where the balance lies, a region may become more `Atlantic' (warm and salty) or more `Arctic' (cold and fresh). The impact of this shift in oceanic conditions will have undoubted impact on regional climate, ecosystem structure and biogeochemical cycling. Further, instances of this shift may be recorded in Arctic sediment records providing a palaeo-record of local ocean conditions. In this paper we look at the mechanisms, magnitude and the regional significance of Atlantic Water intrusions into Kongsfjord on the west coast of Spitsbergen. Data from a long-duration, multi-parameter mooring and a database of CTDs are supplemented with model output from the Bergen Ocean Model. On the West Spitsbergen shelf, cold water of Arctic origin lies between the mouth of the fjord and the northward flowing Atlantic water in the West Spitsbergen Current. Common to high-latitude fjords, Kongsfjorden has high freshwater input from glacial melt and experiences seasonality in the sea-ice cover, wind forcing and precipitation. Consequently, the region is an oceanic system that balances Atlantic, Arctic and fresh water. We show that the intrusion of Atlantic origin water into Kongsfjorden occurs rapidly in early summer causing massive changes in the local hydrography of the fjord. In essence, the fjord flips from being an Arctic fjord to an Atlantic fjord. Exchange across the shelf is shown to be through geostrophic control rather than the more usual hydraulic control. This exchange may also be an important sink for heat transported north in the West Spitsbergen Current. Historic data indicate that the hydrographic switch can be to one that is either strongly or weakly Atlantic - i.e. a `cold' state or a `warm' state. Consequently, Kongsfjorden is an ideal site for studying and monitoring change in the Arctic Marine Environment.
UR: http://www.sams.ac.uk
DE: 4207 Arctic and Antarctic oceanography
DE: 4215 Climate and interannual variability (3309)
DE: 4219 Continental shelf processes
DE: 4283 Water masses
DE: 4536 Hydrography
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting