HR: 1300h
AN: OS52D-03    [PDF]
TI: Mechanisms of Interannual Variability in the Equatorial Atlantic From High-Resolution Ocean Modelling
AU: * Huettl, S
EM: shuettl@ifm.uni-kiel.de
AF: Institute of Marine Sciences, Duesternbrooker Weg 20, Kiel, 24105 Germany
AU: Boening, C
EM: cboening@ifm.uni-kiel.de
AF: Institute of Marine Sciences, Duesternbrooker Weg 20, Kiel, 24105 Germany
AB: A host of high-resolution (1/3- to 1/12-degree) ocean models is used to investigate the interannual to decadal variability in circulation features related to the (southern hemisphere) subtropical-tropical cell in the Atlantic Ocean. Using wind stress and heat flux variations based on 40-year time series of NCEP/NCAR data, the variability of the zonally-integrated STC transport is of O(1 Sv). The bulk of the equatorward transport anomalies is confined to the western boundary, and manifested in variations of the NBC. However, off-equatorial fluctuations in STC/NBC-transports do not show a significant coherence beyond 4S: the variability in the equatorial regime, including the EUC and the equatorial upwelling, appears primarily controlled by the local winds. Of particular interest is the extent to which subtropical temperature anomalies, advected into the equatorial upwelling regime via the NBC and EUC, contribute to the interannual SST-variability. The model clearly reveals a sequence of anomalies, propagating along isopycnal surfaces into the NBC. In most instances the signal ceases near 4S due to the superposition of stronger, locally-forced anomalies associated with the variability of the tropical cell (TC). Only in a few cases, corresponding to phases when TC anomalies are weak, the subtropical signal may be followed into the EUC.
DE: 4215 Climate and interannual variability (3309)
DE: 4231 Equatorial oceanography
DE: 4255 Numerical modeling
DE: 4532 General circulation
DE: 4576 Western boundary currents
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting