HR: 1340h
AN: PP23B-1423    [Abstracts]
TI: Holocene Changes in Atmospherical Circulation in the North Atlantic Region - Evidences for Millennial-Scale co-Variability Between Ocean and Atmosphere Circulation
AU: * Lie, O
EM: oyvind.lie@bjerknes.uib.no
AF: Bjerknes Centre for Climate Research, Allegaten 55, Bergen, Hor 5007 Norway
AU: Nesje, A
EM: atle.nesje@geol.uib.no
AF: Department of Earth Science, Allegaten 41, Bergen, 5007 Norway
AU: Dahl, S O
EM: Svein.dahl@geog.uib.no
AF: Department of Geography, Breviksveien 40, Bergen, 5045 Norway
AU: Jansen, E
EM: eystein.jansen@bjerknes.uib.no
AF: Bjerknes Centre for Climate Research, Allegaten 55, Bergen, Hor 5007 Norway
AU: Nordli, O
EM: oyvind.nordli@met.no
AF: Meteorological Institute, Box 43 Blindern , Oslo, N-0313 Norway
AB: Whereas a number of records from the marine realm have demonstrated Holocene changes regarded to be related to overturning circulation in the North Atlantic region, independent information of atmospherical variability from the terrestrial realm have proven more elusive to capture in palaeo-records. This is a major concern, as several studies have suggested that atmospherical forcing may be an important factor to understand the reconstructed variations in ocean circulation trough the Holocene. A number of studies considering the instrumental period have shown (A) that the atmospheric variability associated with the North Atlantic Oscillation (NAO) and sea-level pressure (SLP) in the North Atlantic is amplified in alpine areas on the western side of the Scandinavian mountain range, and is manifested as variations in the total winter accumulation in these areas. Moreover, it is (B) demonstrated that the spatial distribution of winter precipitation can be seen as a direct response to NAO and SLP variations. Three established Holocene glacier reconstructions are transferred into winter-accumulation signal, and viewed as palaeo-gauges of effective precipitation representing three regions in southern Norway, thereby allowing the spatio-temporal variations in winter-precipitation to be reconstructed. The vectors of westerly and southerly air-flow over southern Scandinavia is inversely modeled, and likely pressure-field patterns are identified for the last 6000 years with a 100 yr resolution. By comparing our results with information on North Atlantic Ocean circulation, we can for the first time demonstrate a consistent behavior between the ocean and independently reconstructed atmospherical circulation from the terrestrial realm, thereby presenting post priori support to the a priori hypothesis that wind-fields are inter-connected with variations in the ocean's circulation during the mid to late Holocene.
DE: 3322 Land/atmosphere interactions
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3344 Paleoclimatology
DE: 1824 Geomorphology (1625)
DE: 1863 Snow and ice (1827)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting