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Seminar

Title : First glider observations north of Svalbard in Summer 2017
Name of the speaker : Zoé Koenig
Affiliation : University of Bergen and Norwegian Polar Institute, Bergen
Laboratory organizer : LOCEAN
Date and time : 12-06-2019 11h00
Location : Campus de Jussieu, salle de réunion LOCEAN, tour 45/55, 4eme étage
Summary :

The West Spitsbergen Current (WSC) cools and freshens as it flows northward along the western Svalbard shelf. The cooling takes place at the ocean surface through interaction with the atmosphere and also in subsurface. We present observations with high horizontal resolution (around 2 km) from a SeaExplorer glider deployed in July 2017 for 14 days in the WSC offshore Kongsfjorden around 79°N. They document small lenses (less than 10‐km diameter) of cold (less than 3.8 °C) and fresh (less than 35.2 g/kg) waters in the core of the WSC, coming from the shelf and contributing to its cooling and freshening. Data show that water from the shelf cascades to the bottom of the slope and then detaches on the offshore side of the WSC core where it is baroclinically unstable. The presence of these lenses from the shelf can be related to the wind regime. Strong southerly winds cause upwelling of the warm Atlantic Water onto the shelf in winter. Weak and/or northerly winds allow modified Atlantic Water formed by mixing with cold waters on the shelf to cascade down the slope, leading to lenses of colder and fresher water protruding into the WSC. If lenses are common in the WSC, they could be contributing significantly to its cooling and freshening especially in summer when the influence of the atmosphere on the cooling of the WSC is less important.
This data set is completed by another one collected north of Svalbard in September 2017 that gives a synoptic view of the circulation North of Svalbard in summer 2017.

Contact :

cp@locean-ipsl.upmc.fr