Water renewals and renewal times of the Saguenay Fjord are investigated and classified according to their intrusion depth. Renewal dynamics are controlled by a shallow sill (∼20 m) at the fjord mouth, by large tides that are a distinguishing feature of the Saguenay Fjord and by large vertical mixing inside the inner basin ( K∼10−4 normalm2 normals−1). A mooring was deployed in the inner basin of the fjord to provide a clearer quantitative understanding of the complexity and seasonality of water renewals in this seasonally ice‐covered fjord. The mooring provided information on currents over nearly the entire water column, along with temperature‐salinity at a few discrete depths. Hydrographic temperature and salinity transects spanning multiple seasons and years as well as turbulence profiles were also collected. The observations show that the fjord dynamics are more complex than previously hypothesized, with large changes in renewal event depths leading to three different renewal regimes. Part of this renewal depth variability may be explained by the seasonality of the St. Lawrence estuarine circulation. Because of the large turbulence within the inner basin bottom layer, the density decreases over time such that new deep renewals can occur every year. The mechanisms behind the large vertical mixing cannot yet be clearly identified but a statistically significant correlation ( K∝N−1.3) suggests that internal wave breaking may be a significant contributor to deep turbulence mixing in the inner basin. The renewal time of the inner basin waters is estimated to be between 1 and 6 months.

La circulation de renouvellement des eaux du fjord du Saguenay est examinée à la lumière de nouvelles données océanographiques. Nous avons observé une nouvelle signature de renouvellement en température et salinité occasionnée par la crue printanière, ainsi que le remplacement d’une grande partie des eaux du fjord en moins de 2 mois, confirmant le faible temps de résidence de ces eaux. Un instrument déployé pour mesurer la température et la salinité des eaux à l’entrée du fjord nous a permis de les identifier comme étant principalement des eaux de l’estuaire du Saint-Laurent. Les eaux mesurées dans le premier bassin du fjord à marée basse étaient un mélange des eaux du seuil de salinité parmi les plus faibles observées pendant un cycle de marées, avec des eaux de surface du Saguenay. Ce mélange occasionne ensuite le renouvellement des eaux supérieures et intermédiaires du bassin interne du fjord. La plage de salinité des eaux au seuil correspond assez bien aux eaux qu’on trouve 100 km plus loin dans l’estuaire du Saint-Laurent entre 20 et 70 m. Les variations synchrones de salinité à 100 km et au seuil suggèrent un mouvement vertical simultané des eaux dans tout l’estuaire qui serait déterminant pour le type et la vitesse de renouvellement du fjord du Saguenay.

Ocean gliders are versatile tools for making ocean observations. This paper summarizes the experience, of nearly two decades, of glider observing activity in Atlantic Canada. It reviews key considerations for operating gliders based on the experience and the lessons learned. This paper has three main goals: 1. To provide new and emerging glider users with guidance and considerations for developing a glider program. 2. Review the literature on sensor development for gliders and the use of gliders. 3. To highlight different mission scenarios that include enough practical considerations to support operating gliders. The use of gliders is rapidly expanding, but the documentation and consolidation of best practices for their operational use in Atlantic Canada remains underdeveloped. This summary provides a guide that should be helpful both to new and experienced glider operators and potential users, to observe the oceanography of this region and addresses regional challenges. We believe documenting our experience will be also helpful to the global glider community. We summarize the most critical considerations of utilizing gliders. We review the issues specific to the platform use and concerns about how to optimize the use of key sensors to contribute to an oceanographic observing program.

L'inventaire des terres du Canada, section Québec, travaille depuis plusieurs années à la réalisation d'études de classement des sols selon leurs possibilités d'utilisation agricole, forestière, récréative et faunique.