Preprints
https://doi.org/10.5194/tc-2021-136
https://doi.org/10.5194/tc-2021-136

  12 May 2021

12 May 2021

Review status: this preprint is currently under review for the journal TC.

Recent observations of superimposed ice and snow ice on sea ice in the northwestern Weddell Sea

Stefanie Arndt1, Christian Haas1, Hanno Meyer2, Ilka Peeken1, and Thomas Krumpen1 Stefanie Arndt et al.
  • 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany
  • 2Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 14473 Potsdam, Germany

Abstract. Recent low summer sea ice extent in the Weddell Sea raises questions about the contributions of dynamic and thermodynamic atmospheric and oceanic energy fluxes. The roles of snow, superimposed ice, and snow ice are particularly intriguing, as they are sensitive indicators for changes in atmospheric forcing, and as they could trigger snow-albedo feedbacks that could accelerate ice melt. Here we present snow depth data and ice core observations of superimposed ice and snow ice collected in the northwestern Weddell Sea in late austral summer of 2019, supplemented by airborne ice thickness measurements. Texture, salinity, and oxygen isotope analyses showed mean thicknesses of superimposed and snow ice of 0.11 ± 0.11 m and 0.22 ± 0.22 m, respectively, or 3 to 54 % of total ice thickness. Mean snow depths ranged between 0.46 ± 0.29 m in the south to 0.05 ± 0.06 m in the north, with mean and modal, total ice thicknesses between 4.12 ± 1.87 m to 1.62 ± 1.05 m, and 3.9 m to 0.9 m, respectively. These snow and ice properties are similar to results from previous studies, suggesting that the ice’s summer surface energy balance and related seasonal transition of snow properties have changed little in past decades. This is supported by our additional analyses of the summer energy balance using atmospheric reanalysis data, and melt onset observations from satellite scatterometry showing little recent changes.

Stefanie Arndt et al.

Status: open (until 17 Jul 2021)

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  • RC1: 'Comment on tc-2021-136', Anonymous Referee #1, 11 Jun 2021 reply

Stefanie Arndt et al.

Stefanie Arndt et al.

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Short summary
We present here snow and ice core data from the northwestern Weddell Sea in late austral summer 2019, which allow insights into possible reasons for the recent low summer sea ice extent in the Weddell Sea. We suggest that the fraction of superimposed ice and snow ice can be used here as a sensitive indicator. However, snow and ice properties were not exceptional, suggesting that the summer surface energy balance and related seasonal transition of snow properties have changed little in the past.