Passive surface drifter data in the bay of Sept-Îles in 2017-2018

Lagrangian drift data were gathered in the Bay of Sept-Îles during the Spring and Summer in 2017 and 2018, as part of the Canadian Healthy Oceans Network (CHONe II) program. The drifters were deployed from shore and from two local fishing vessels: the Monica and Yvan-Raymond. The drifters consisted of a Spot Trace GPS emitter fixed on a wooden circular base 30 cm in diameter with a 0.9 kg weight attached to the opposite side to ensure that the emitter stays above water. Positions were recorded every 10 minutes. Data remaining persistently at low depth (<2 m) and low speed (<5 cm s-1) were considered shoaled and removed. A purpose-built graphical user interface program was used to remove GPS points on land or on the boat, and separate the GPS traces of each device into continuous movements (uninterrupted by shoaling). Positions were linearly interpolated to a 10 minute grid after quality control

ADCP current measurements in the bay of Sept-Îles in 2018

Water velocity profiles were gathered in the Bay of Sept-Îles from the 16th to the 18th of May, 2018, as part of the Canadian Healthy Oceans Network (CHONe II) program. Current profiles were collected using a Teledyne RDI Sentinel V 500 kHz ADCP fixed on a Biosonics BioFin aluminum towing body and towed at a speed of approximately 2 m s−1. The ping frequency and vertical resolution were set to 0.5 Hz and 0.5 m yielding a 50 m depth range. The mean depth of the towing body was 0.9 m and the centre of the first bin was 2.6 m deep. Towed ADCP velocities were smoothed with a 63 ping horizontal moving average and gridded at a resolution approximately equivalent to the distance travelled by the boat in the corresponding time (252 m). Water velocity data were collected inside the bay during flood tide. Repeated passages were also conducted at the mouth of the bay, between the port of Sept-Îles and Pointe à la Marmite during one semidiurnal tide cycle (12 h)

Physical oceanographic data in the bay of Sept-Îles measured by SBE 19plus CTD probe in 2017

Temperature, salinity, dissolved oxygen, turbidity and fluorescence data were gathered in the Bay of Sept-Îles during the Spring and Summer in 2017, as part of the Canadian Healthy Oceans Network (CHONe II) program. These were profiles were collected during 5 separate campaigns (2 in May, 2 in June, and 1 in September) at 21 stations in the bay and archipelago. On two occasions (late June and September), repeated passages were also conducted at the mouth of the bay, between the port of Sept-Îles and Pointe à la Marmite during one semidiurnal tide cycle (12 h). Although other measurements were collected continuously, CTD data were gathered once every three passages at the beginning, middle, and end of the passage. The data were collected from the local fishing vessel Yvan-Raymond using a Seabird electronics SBE 19plus CTD probe

Physical oceanographic data in the bay of Sept-Îles measured by Sontek CastAway CTD probe in 2018

Temperature and salinity data were gathered in the Bay of Sept-Îles from the 16th to the 18th of May, 2018, as part of the Canadian Healthy Oceans Network (CHONe II) program. Repeated passages were then conducted at the mouth of the Bay, between the port of Sept-Îles and Pointe à la Marmite during one semidiurnal tide cycle (12 h). Although other measurements were collected continuously, CTD data were gathered once every three passages at the beginning, middle, and end of the passage. The data were collected from the hydrological survey vessel F. J. Saucier using a Sontek CastAway CTD probe

Physical oceanographic data in the bay of Sept-Îles

This data set contains temperature, salinity, oxygen, fluorescence, turbidity, currents, and lagrangian drift data collected in the bay of Sept-Îles, on the north shore of the Gulf of St. Lawrence, Canada. Five sampling campaigns were conducted from May to September of 2017, to assess seasonal variations in the oceanographic conditions. An additional campaign was conducted in May 2018, focusing on the measurement of currents. These surveys covered the inside of the bay and the nearby archipelago. The bay of Sept-Îles has recently been the subject of a multidisciplinary study by the Canadian Healthy Oceans Network (CHONe II) because it is a heavily industrialized and urban coastal area at Canadian midlatitudes. It is therefore a good site to study the impact of such human presence on adjacent marine ecosystems. The objective of this data set was to enable the development and calibration of hydrodynamic and biogeochemical models of the bay, which was hindered by scarce knowledge of the environmental conditions. Water properties were collected using a Seabird Electronics SBE19plus and a Sontek CastAway CTD probe. Currents were measured using a towed acoustic Doppler current profiler (ADCP) model Teledyne RDI Sentinel V, and passive surface drifters which used Spot GPS probes

Passive surface drifter data in the bay of Sept-Îles in 2003

Lagrangian drift data were gathered by Denis Lefaivre in the Bay of Sept-Îles in 2003 as part of work for the Department of Fisheries and Oceans, Canada (DFO). The drifters were deployed from the small DFO boat Barachois, and consisted of 2 m long by 10.16 cm wide PVC tubes. These were weighted on one end and affixed with a 22.86 cm ring 20 cm from the other, to increase stability. Positions were recorded every 2 minutes by a GPS emitter inside the top 20 cm of the tube, which remained above water. Sampling was done from September 9 to 11, 2003

Modélisation de la circulation dans l'estuaire et le golfe du Saint-Laurent en réponse aux variations du débit d'eau douce et des vents

Nous examinons des résultats récents issus d'observations et de simulations numériques de la circulation générale et du climat de l'estuaire moyen et du golfe du Saint-Laurent. Nous focalisons cette étude sur l'intensité de la circulation estuarienne. L'approche méthodologique est présentée avec une emphase sur l'intégration, à l'aide de simulations numériques, des processus clés tels que le mélange turbulent associé aux marées à la tête du chenal laurentien et les échanges atmosphère-océan dans l'ensemble de l'estuaire maritime et du golfe. Les simulations numériques permettent de suivre l'évolution de la circulation et du climat sur des périodes de quelques heures à plusieurs années. Nous examinons d'une part la variabilité tidale de la circulation à la tête du chenal Laurentien et dans l'estuaire moyen, illustrant l'importance des processus qui gouvernent largement la circulation estuarienne du Saint-Laurent. Ces principaux processus sont les instabilités dynamiques associées à l'étirement de marée et aux sauts hydrauliques internes aux abords des seuils. D'autre part, la contrainte du vent est dominante pour propulser les eaux douces vers l'océan Atlantique dans l'estuaire maritime et le golfe. À l'aide d'expériences de sensibilité, les effets sur la circulation de variations dans l'apport d'eau douce et dans l'intensité des vents sont isolés. Les résultats montrent que notre modèle du Saint-Laurent répond aux forçages externes à l'instar d'un estuaire classique à deux couches lors des périodes de forte stratification (printemps et été), c'est-à-dire lorsque l'apport en eau douce entraîne une intensification de la circulation de la couche intermédiaire froide du golfe vers le continent jusqu'à une profondeur d'environ 150m. D'autre part, lors des périodes de plus faible stratification (automne et hiver), la contrainte du vent gouverne la circulation des couches d'eau profondes (plus de 150m) vers le continent. Un excès dans l'apport d'eau douce inhibe partiellement leur ventilation, comme dans une mer marginale nordique. Ces résultats suggèrent qu'une diminution éventuelle de l'apport en eau douce du fleuve Saint-Laurent, associée au réchauffement climatique ou au développement, pourrait diminuer l'intensité de la circulation estuarienne au printemps et à l'été. Durant l'hiver, une diminution du débit pourrait favoriser l'apport en eaux profondes du chenal Laurentien