EGU2020-22464, updated on 12 Jun 2020
https://doi.org/10.5194/egusphere-egu2020-22464
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The role of tides in ocean--ice-shelf interactions in the southwestern Weddell Sea

Ute Hausmann1, Jean-Baptiste Sallée1, Nicolas Jourdain2, Pierre Mathiot3, Clement Rousset1, Gurvan Madec1, Julie Deshayes1, and Tore Hattermann4
Ute Hausmann et al.
  • 1Sorbonne-Universite, LOCEAN-IPSL, Paris, France (uhausc@gmail.com)
  • 2Univ. Grenoble Alpes/CNRS/IRD/G-INP, IGE, Grenoble, France
  • 3Met Office, Exeter, United Kingdom
  • 4AWI, Bremerhaven, Germany

A novel regional ocean-sea-ice model configuration is designed to investigate the mechanisms of ocean–ice-shelf-melt interactions in the Weddell Sea. It features explicit resolution of the cavities of eastern Weddell, Larsen and Filchner-Ronne ice-shelves (FRIS, at 1.5-2.5 km horizontal resolution), as well as of the adjacent continental shelves (~2.5 km) and deep open-ocean gyre (at 2.5-4 km), in presence of interannually-varying atmospheric and ocean boundary forcing as well as explicit ocean tides. Simulated circulation, water mass and ice-shelf melt properties compare overall well with available open-ocean and cavity observations, and simulated Weddell ice-shelf melting reveals large variability on tidal, seasonal and year-to-year timescales. The presence of ocean tides, investigated explicitly, is revealed to result in a systematic time-average enhancement of both the production of ice-shelf meltwater as well as its refreezing on ascending branches of especially the FRIS cavity circulation. This tide-driven enhancement of the melt-induced FRIS cavity circulation acts to increase net ice-shelf melting (by 50%, ~50 Gt/yr) and the meltwater export by the FRIS outflow, and modulates their seasonal and lower frequency variability. The tidal impact on ice-shelf melting is consistent with being primarily driven mechanically through enhanced kinetic energy of the time-varying flow in contact with the ice drafts. The dynamically-driven tide-induced melting is thereby to almost 90% compensated by cooling through meltwater produced, but not quickly exported from regions of melting in the Weddell cold-cavity regime. Ocean boundary layer thermal adjustment underneath ice drafts, minimizing departures from the in-situ freezing point, thus substantially dampens the impact of tides on Weddell ocean–ice-shelf interactions. Simulations furthermore suggest attendant changes on the open-ocean continental shelves, characterized by overall freshening and modest year-round sea-ice thickening, as well as a marked freshening of newly-formed bottom waters in the southwestern Weddell Sea.

How to cite: Hausmann, U., Sallée, J.-B., Jourdain, N., Mathiot, P., Rousset, C., Madec, G., Deshayes, J., and Hattermann, T.: The role of tides in ocean--ice-shelf interactions in the southwestern Weddell Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22464, https://doi.org/10.5194/egusphere-egu2020-22464, 2020

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