The transport of water, heat and salt through the strait of Belle Isle

Abstract

We present an analysis of current-meter, sea-level and hydrographic data collected in the Strait of Belle Isle and the northeastern Gulf of St Lawrence. From an array of moorings in the Strait from July to October 1980, we calculate a net transport into the Gulf of 0.13 × 10 6 m 3 s -1 and show that the mean and eddy fluxes of heat through the Strait represented a net loss of heat to the northeastern Gulf. The estimated rate of loss of heat is less than the long-term mean computed by Bugden (1981) but becomes comparable if adjusted for interannual changes of transport and water temperature. Moreover, the 1980 data permit the permanent tide-gauge stations in the Strait at West Ste Modeste and Savage Cove to be levelled relative to one another, thus allowing surface currents to be calculated from sea-level alone. Hence the long-term wintertime transport into the Gulf can be calculated after fractional effects on the vertical structure of the flow are considered. During an average winter it appears that advection through the Strait can account for about 35% of the Gulf Intermediate Layer. A multiple regression involving average Intermediate Layer temperatures over 9 years suggests that winter air temperature in the Gulf, representative of atmospheric cooling, and sea-level difference across the Strait, representative of advection, are equally important variables and together account for 50% of the Layer's temperature variability. Analysis of current-meter, sea-level and hydrographic data collected in 1975 supports earlier hypotheses that the strongest inflow of water with Τ < 0° C and salinity between 32 and 3 3 should occur in winter. It appears that during the 1975 field program the inflow was about 0.6 × 10 6 m 3 s -1 , which is about twice the long-term average for January to May. RÉSUMÉ Nous présentons une analyse des données de courantomètres, et de mesures du niveau de la mer et hydrographiques recueillies dans le détroit de Belle-Isle et la partie nord-est du golfe du Saint-Laurent. A partir du réseau de bouées amarrées dans le détroit de juillet à octobre 1980, nous calculons un transport net dans le golfe de 0,13 × 10 6 m 3 s -1 et ATMOSPHERE-OCEAN 26 (2) 1988, 234-251 0705-5900/88/OO0O-0234$01.25/0 © Canadian Meteorological and Océanographie Society Downloaded by [UQ Library] at 15:27 26 July 2015 Transport of Water, Heat and Salt Through the Strait of Belle Isle / 235 montrons que le flux moyen de chaleur et les mouvements thermiques de tourbillon dans le détroit ont présenté une perte nette de chaleur vers la zone nord-est du golfe en 1980. Le débit estimé de chaleur perdue est inférieur à la moyenne à long terme calculée par Bugden (1981), mais s'en approche lorsque corrigé pour les variations interannuelles de transport et de température de l'eau. De plus, les données de 1980 permettent de comparer les niveaux des stations marégraphiques permanentes de Ste-Modeste-Ouest et de Savage Cove dans le détroit, et de calculer les courants de surface à partir du seul niveau de la mer. Ainsi, on peut calculer ...

Modeling the formation and circulation processes of water masses and sea ice in the Gulf of St. Lawrence, Canada

“…In the present simulation, the mean transport is minimum during winter and maximum during the fall. The modeled inward transport through the Strait of Belle Isle is 0.33 Sv on the average in 1997, highly variable on synoptic timescales, with a larger mean inflow during the fall and winter months (mean 0.42 Sv) and minimum inflow during spring (0.15 Sv), in rough agreement with Petrie et al [1988] (who derived 0.3 Sv for winter and 0.13 Sv for summer using measurements acquired in earlier years).…”

“…This important contribution carries large uncertainties due to the lack of data near the boundary, but is in rough agreement with previous estimates of about 26 to 50% by Banks [1966] and Petrie et al [1988].…”

“…The inflow of waters through the Strait of Belle Isle is clearly very important in the heat, salt, and momentum budget of the GSL [e.g., see also Bugden, 1981;Petrie et al, 1988]. The lack of data on water properties and sea level in the Strait of Belle Isle is thus very limiting until we can properly monitor the conditions there.…”

Description du régime alimentaire et comparaison de la niche alimentaire des larves de trois espèces de poisson fourragères dans le nord du golfe du Saint-Laurent :

“…L'origine estuarienne et la présence de remontées d'eau profonde par forçage à plusieurs endroits rendent cette couche riche en nutriments, mais peu productive en hiver dû à un ensoleillement réduit, au couvert de glace et à l'épaisseur de la couche de mélange (De Lafontaine et al, 1989;Galbraith, 2006 (Pétrie et al, 1988;Koutitonski, 1989;Smith et al, 2006). (Martell & McClelland, 1994;Bundy et al, 2009;Morissette et al, 2009 Sans des connaissances plus approfondies, on peut difficilement expliquer les liens trophiques de ces populations en milieu naturel.…”

Evaluation of an operational ice–ocean analysis and forecasting system for the Gulf of St Lawrence

“…The northeast GSL is a region strongly influenced by an inflow of about 0.3 Sv of relatively cold waters from the Labrador Shelf (Petrie et al, 1988;Smith et al, 2006). These waters enter the gulf and flow mostly along the north coast, submerging below the lighter surface waters (Galbraith, 2006).…”