2004 LOM Workshop

Wednesday 4:20 - 4:40 p.m.

Study of the Slopewater current from MICOM high resolution simulation outputs.

Angelique Haza, Arthur Mariano, Mike Chin, Donald Olson
RSMAS/ University of Miami
ahaza@rsmas.miami.edu

ABSTRACT

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The Gulf Stream-Slopewater system is analyzed from four year-outputs of MICOM high-resolution simulations of the North Atlantic, forced by the ECMWF 6 hourly winds. The code was able to reproduce an eastward surface current in the Slope water region, with characteristics similar to the Slopewater Jet measured from hydrographic surveys. The mean path of the Slope current coincides with the sharp temperature and salinity surface fronts separating the Shelf waters from the Slope waters. Its mean transport doubles from 7-9 Sv downstream of the NESC, to 19 Sv south of the Grand Banks. A Taylor column effect of the NESC appears to be the main mechanism captured by the numerical model to account for the strong upper ocean-topographic coupling, resulting in a Gulf Stream bifurcation downstream of the chain and transport increase of the Slopewater current. The coherence and path of this current are maintained by the combination of the western intensification, and the vertical velocity shear of the DWBC, which acts as a barrier. Statistical analysis of the variability shows that the Slope Jet's path and transport are influenced by lateral shift and feeding of the Gulf Stream shortly downstream of the NESC, with 9 month and 1 year periodicities, while near the Grand Banks, the currents are regrouped and accelerated in this zone of convergence, and the SJ only varies in intensity. Mean flow and EOF analyses show good agreement with the latest observations on the Slopewater current, including a coupling in intensity of the Slope Jet with the DWBC and Labrador current.

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LOM Users' Workshop, February 9-11, 2004