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Labrador Sea winter heat and freshwater content observations from glider and Argo data
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  • Nicolai von Oppeln-Bronikowski,
  • Brad deYoung,
  • Eleanor Frajka-Williams,
  • Ilona Goszczko,
  • Louis Clement
Nicolai von Oppeln-Bronikowski
Memorial University

Corresponding Author:[email protected]

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Brad deYoung
Memorial University
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Eleanor Frajka-Williams
National Oceanography Centre
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Ilona Goszczko
Institute of Oceanology, Polish Academy of Sciences
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Louis Clement
National Oceanography Centre
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Abstract

The Labrador Sea undergoes deep mixing in the wintertime, with mixed layer depths frequently reaching down to 2000 m. The resulting water mass that is formed - Labrador Sea Water (LSW) - has long been thought to be important for the deep Western Boundary Current (dWBC) and the upper limb of the AMOC. Direct observations of the overturning have, however, been rather limited. Limited Argo profiles and moorings in key locations offered winter measurements in a region challenged by severe weather conditions. Here we discuss observations of a winter-spring glider deployment in the Labrador Sea, but more specifically where deep convection occurs, from December 2019- to June 2020. Using the glider data, we describe the evolution of the mixed layer, changes in heat and freshwater content for surface (0-500 m) and intermediate depth (500-1000 m) layers for the central Labrador Sea convection region inside a box 200 by 100 km wide and spatial scales of T and S. We compare the observations with reanalysis data (air-sea heat fluxes and winds) and Argo profiles to better understand the variability missed by existing datasets. These observations highlight the role played by eddies in the overall variability of heat and salt in this region, something that is missed by Argo observations. They also show changes in spatial scales of T-S over the months from January to May, pointing towards the modulating effect of eddies on LSW winter formation.