A mechanism for Atlantic multidecadal variability in the Kiel Climate Model.

Ba, Jin, Keenlyside, Noel S., Park, Wonsun , Latif, Mojib , Hawkins, Ed and Ding, Hui (2013) A mechanism for Atlantic multidecadal variability in the Kiel Climate Model. Climate Dynamics, 41 (7-8). pp. 2133-2144. DOI 10.1007/s00382-012-1633-4.

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Atlantic Multidecadal Variability (AMV) is investigated in a millennial control simulation with the Kiel Climate Model (KCM), a coupled atmosphere–ocean–sea ice model. An oscillatory mode with approximately 60 years period and characteristics similar to observations is identified with the aid of three-dimensional temperature and salinity joint empirical orthogonal function analysis. The mode explains 30 % of variability on centennial and shorter timescales in the upper 2,000 m of the North Atlantic. It is associated with changes in the Atlantic Meridional Overturning Circulation (AMOC) of ±1–2 Sv and Atlantic Sea Surface Temperature (SST) of ±0.2 °C. AMV in KCM results from an out-of-phase interaction between horizontal and vertical ocean circulation, coupled through Irminger Sea convection. Wintertime convection in this region is mainly controlled by salinity anomalies transported by the Subpolar Gyre (SPG). Increased (decreased) dense water formation in this region leads to a stronger (weaker) AMOC after 15 years, and this in turn leads to a weaker (stronger) SPG after another 15 years. The key role of salinity variations in the subpolar North Atlantic for AMV is confirmed in a 1,000 year long simulation with salinity restored to model climatology: No low frequency variations in convection are simulated, and the 60 year mode of variability is absent.

Document Type: Article
Additional Information: WOS:000324812200025
Keywords: Atlantic meridional overturning circulation; AMOC; Atlantic multidecadal variability; AMV; AMO; Salinity
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Refereed: Yes
Open Access Journal?: No
Publisher: Springer
Projects: THOR, SUMO, STEPS, Future Ocean, KCM
Date Deposited: 10 Jan 2013 07:11
Last Modified: 23 Sep 2019 21:47
URI: https://oceanrep.geomar.de/id/eprint/19943

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