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Meltwater lenses over the Chukchi and the Beaufort seas during summer 2019: from in-situ to synoptic view.
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  • Alexandre Supply,
  • Jacqueline Boutin,
  • Nicolas Kolodziejczyk,
  • Gilles Reverdin,
  • Camille Lique,
  • Jean-Luc Vergely,
  • Xavier Perrot
Alexandre Supply
Laboratoire d'Océanographie Physique et Spatiale, Laboratoire d'Océanographie Physique et Spatiale, Laboratoire d'Océanographie Physique et Spatiale

Corresponding Author:[email protected]

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Jacqueline Boutin
French National Centre for Scientific Research (CNRS), French National Centre for Scientific Research (CNRS), French National Centre for Scientific Research (CNRS)
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Nicolas Kolodziejczyk
LOPS, University of Brest, LOPS, University of Brest, LOPS, University of Brest
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Gilles Reverdin
Sorbonne Université, CNRS/IRD/MNHN, LOCEAN-IPSL, Sorbonne Université, CNRS/IRD/MNHN, LOCEAN-IPSL, Sorbonne Université, CNRS/IRD/MNHN, LOCEAN-IPSL
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Camille Lique
Laboratoire d'Océanographie Physique et Spatiale, Laboratoire d'Océanographie Physique et Spatiale, Laboratoire d'Océanographie Physique et Spatiale
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Jean-Luc Vergely
ACRI-st, ACRI-st, ACRI-st
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Xavier Perrot
Ecole Normale Supérieure, Ecole Normale Supérieure, Ecole Normale Supérieure
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Abstract

We investigate the Chukchi and the Beaufort seas, where salty and warm Pacific Water flows in from the Bering Strait and interacts with the sea ice, contributing to its summer melt. For the first time, thanks to in-situ measurements recorded by two saildrones deployed during summer 2019 and to refined sea ice filtering in satellite L-Band radiometric data, we demonstrate the ability of satellite Sea Surface Salinity (SSS) observed by SMOS and SMAP to capture SSS freshening induced by sea ice melt, referred to as meltwater lenses (MWL). The largest MWL observed by the saildrones during this period occupied a large part of the Chukchi shelf, with a SSS freshening reaching -5 pss. it persisted for up to one month, to this MWL, induced low SSS pattern which restricted the transfer of air-sea momentum to the upper, as illustrated by measured wind speed and vertical profiles of currents. Combined with satellite-based Sea Surface Temperature, satellite SSS provides a monitoring of the different water masses encountered in the region during summer 2019. Using sea ice concentration and estimated Ekman transport, we analyse the spatial variability of sea surface properties after the sea ice edge retreat over the Chukchi and the Beaufort seas. The two MWL captured by both, the saildrones and the satellite measurements, result from different dynamics. Over the Beaufort Sea, the MWL evolution follows the meridional sea ice retreat, whereas in the Chukchi Sea, a large persisting MWL is generated by advection of a sea ice filament.