25 Jul 2023
 | 25 Jul 2023
Status: a revised version of this preprint is currently under review for the journal TC.

Observations of preferential summer melt of Arctic sea-ice ridge keels from repeated multibeam sonar surveys

Evgenii Salganik, Benjamin Allen Lange, Christian Katlein, Ilkka Matero, Philipp Anhaus, Morven Muilwijk, Knut Vilhelm Høyland, and Mats Anders Granskog

Abstract. Sea-ice ridges constitute a large fraction of the total Arctic sea-ice area (up to 40–50 %); nevertheless, they are the least studied part of the Arctic ice pack. Here we investigate sea-ice melt rates using rare repeated underwater multibeam sonar surveys that cover a period of one month during the advanced stage of sea-ice melt. We show that the degree of bottom melt increases with ice draft for first-year and second-year level ice, and a first-year ice ridge, with an average of 0.45 m, 0.55 m, and 0.95 m of total snow and ice melt in the observation period, respectively. We investigated the Arctic first-year ice ridge with a 4.6 m average keel draft, 42 m width, and 4 % macroporosity. While bottom melt rates of ridge keel were 4 times higher than first-year level ice, surface melt rates were almost identical and responsible for 40 % of ridge draft decrease. We show high spatial variability of ridge keel cross-sectional melt ranging from 0.2 m to 2.6 m with the maximum point ice loss of 6 m. We attribute 57 % of the ridge total melt variability to keel draft (36 %), slope (32 %), and width (27 %), with higher melt for ridges with larger draft, steeper slope, and smaller width. The melt rate of ridge keel flanks was proportional to the draft, while there was increased keel melt within 10 m of its bottom corners, and the melt rates of the keel bottom were comparable to level ice melt.

Evgenii Salganik et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2023-106', Stefan Kern, 24 Aug 2023
    • AC1: 'Reply on RC1', Evgenii Salganik, 02 Sep 2023
  • RC2: 'Comment on tc-2023-106', Anonymous Referee #2, 04 Sep 2023
    • AC2: 'Reply on RC2', Evgenii Salganik, 07 Sep 2023

Evgenii Salganik et al.

Evgenii Salganik et al.


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Short summary
The Arctic Ocean is covered by a layer of sea ice that can break up, forming ice ridges. Here we measure ice thickness using an underwater sonar and compare ice thickness reduction for different ice types. We also study how the shape of ridged ice influences how it melts, showing that deeper, steeper, and narrower ridged ice melts the fastest. We show that deformed ice melts 4 times faster than undeformed ice at the bottom ice-ocean boundary, while at the surface they melt at a similar rate.