Saucier Francois J.

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Saucier
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Francois J.
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  • Preprint
    The outflow from Hudson Strait and its contribution to the Labrador Current
    ( 2007-11) Straneo, Fiamma ; Saucier, Francois J.
    Hudson Strait delivers a large amount of fresh water to the subpolar North Atlantic due to a large riverine input into the upstream Hudson Bay System and to the rerouting of Arctic Ocean waters. The fresh waters flowing out of Hudson Strait feed the Labrador Current, a current that has a significant impact on the climate and ecosystem of the entire northeastern seaboard. The lack of measurements from the strait have, until recently, made it difficult to determine the relative contribution of Hudson Strait to the properties and variability of the Labrador Current compared to other sources. This study describes the first year round observations of the outflow as obtained from a moored array deployed midstrait from August 2004 to 2005, and from a highresolution hydrographic section conducted in September of 2005. The outflow from Hudson Strait has the structure of a buoyant boundary current spread across the sloping topography of its southern edge. The variability in the flow is dominated by the extreme semidiurnal tides and by vigorous, mostly barotropic, fluctuations over several days. The fresh water export is seasonally concentrated between June and March with a peak in NovemberDecember, consistent with the seasonal riverine input and seaice melt. It is highly variable on weekly timescales due to synchronous salinity and velocity variations. The estimated volume and liquid fresh water transports during 20042005 are respectively of 11.2 Sv and 7888 (2829) mSv relative to a salinity of 34.8 (33). This implies that the Hudson Strait outflow accounts for approximately 15% of the volume and 50% of the fresh water transports of the Labrador Current. This larger than previously estimated contribution is partially due to the recycling, within the Hudson Bay System, of relatively fresh waters that flow into Hudson Strait, along its northern edge. It is speculated that the source of this inflow is the outflow from Davis Strait.
  • Article
    Behaviour of the ocean DMS(P) pools in the Sargasso Sea viewed in a coupled physical-biogeochemical ocean model
    (National Research Council Canada, 2004-06-23) Le Clainche, Yvonnick ; Levasseur, Maurice ; Vezina, Alain ; Dacey, John W. H. ; Saucier, Francois J.
    The dimethylsulfide (DMS) production model NODEM (Northern Oceans DMS Emission Model) was coupled with the water column ocean model GOTM (General Ocean Turbulence Model) that includes a two-equation k&150;ε turbulence scheme. This coupled physical-biogeochemical ocean model represents a significant improvement over the previous uncoupled version of NODEM that was driven by a diagnostic vertical mixing scheme. Using the same set of biogeochemical parameters, the coupled model is used to simulate the annual cycles of 1992 and 1993 at Hydrostation S in the Sargasso Sea. The better reproduction of the turbulent mixing environment corrects some deficiencies in nitrogen cycling, especially in the seasonal evolution of the nutrient concentrations. Hence, the coupled model captures the late-winter chlorophyll- and DMS(P)-rich blooms. It is also more adept at reproducing the vertical distribution of chlorophyll and DMS(P) in summer. Moreover, the DMS pool becomes less dependent on parameters controlling the nitrogen cycle and relatively more sensitive to parameters related to the sulfur cycle. Finally, the coupled model reproduces some of the observed differences in DMS(P) pools between 1992 and 1993, the latter being an independent data set not used in calibrating the initial version of NODEM.