Intercomparison of simulated South Equatorial Current Bifurcation
Abstract
The gradual weakening of the Atlantic Meridional Overturning Circulation (AMOC) during the twenty-first century, as predicted by climate models contributing to the 4th IPCC report, motivated numerous studies of the AMOC using observations and model simulations in the North Atlantic, but only few studies have focused on the South Atlantic. This study investigates and intercompares the AMOC in the South Atlantic in SODA ocean reanalysis and various model simulations. Close to Brazilian shelf, the North Brazilian Undercurrent (NBUC) is one of the main conduits for AMOC upper branch. Another one is the Intermediate Western Boundary Current (IWBC). Both of these western boundary currents are affected by the South Equatorial Current bifurcation. Since the bifurcation is under distinct regimes in the surface and intermediate depths with dissimilar temporal variability, at least at seasonal timescales, NBUC and IWBC systems are expected to contribute differently to AMOC variability. We test this hypothesis using the outputs of 3 ocean-only models of varying resolution (1, 1/2 and 1/12 deg) forced by atmospheric reanalyses, and the ocean reanalysis SODA. Preliminary investigations concern the time variability of the bifurcation position, on seasonal to interannual timescales, and its relationship with atmospheric forcings (e.g. wind stress curl) and global climate indices (such as AMOC, ENSO, NAO, AMO…).
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSMOS33A..01S
- Keywords:
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- 4576 OCEANOGRAPHY: PHYSICAL / Western boundary currents;
- 4255 OCEANOGRAPHY: GENERAL / Numerical modeling;
- 4513 OCEANOGRAPHY: PHYSICAL / Decadal ocean variability