Wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study
Fragmentation of the sea ice cover by ocean waves is an important mechanism impacting ice evolution. Fractured ice is more sensitive to melt, leading to a local reduction in ice concentration, facilitating wave propagation. A positive feedback loop, accelerating sea ice retreat, is then introduced....
Published in: | The Cryosphere |
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Online Access: | https://doi.org/10.5194/tc-16-4447-2022 https://tc.copernicus.org/articles/16/4447/2022/ |
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ftcopernicus:oai:publications.copernicus.org:tc100306 2023-05-15T18:17:00+02:00 Wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study Mokus, Nicolas Guillaume Alexandre Montiel, Fabien 2022-10-20 application/pdf https://doi.org/10.5194/tc-16-4447-2022 https://tc.copernicus.org/articles/16/4447/2022/ eng eng doi:10.5194/tc-16-4447-2022 https://tc.copernicus.org/articles/16/4447/2022/ eISSN: 1994-0424 Text 2022 ftcopernicus https://doi.org/10.5194/tc-16-4447-2022 2022-10-24T16:22:41Z Fragmentation of the sea ice cover by ocean waves is an important mechanism impacting ice evolution. Fractured ice is more sensitive to melt, leading to a local reduction in ice concentration, facilitating wave propagation. A positive feedback loop, accelerating sea ice retreat, is then introduced. Despite recent efforts to incorporate this process and the resulting floe size distribution (FSD) into the sea ice components of global climate models (GCMs), the physics governing ice breakup under wave action remains poorly understood and its parametrisation highly simplified. We propose a two-dimensional numerical model of wave-induced sea ice breakup to estimate the FSD resulting from repeated fracture events. This model, based on linear water wave theory and visco-elastic sea ice rheology, solves for the scattering of an incoming time-harmonic wave by the ice cover and derives the corresponding strain field. Fracture occurs when the strain exceeds an empirical threshold. The geometry is then updated for the next iteration of the breakup procedure. The resulting FSD is analysed for both monochromatic and polychromatic forcings. For the latter results, FSDs obtained for discrete frequencies are combined following a prescribed wave spectrum. We find that under realistic wave forcing, lognormal FSDs emerge consistently in a large variety of model configurations. Care is taken to evaluate the statistical significance of this finding. This result contrasts with the power law FSD behaviour often assumed by modellers. We discuss the properties of these modelled distributions with respect to the ice rheological properties and the forcing waves. The projected output can be used to improve empirical parametrisations used to couple sea ice and ocean wave GCM components. Text Sea ice Copernicus Publications: E-Journals The Cryosphere 16 10 4447 4472 |
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Copernicus Publications: E-Journals |
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English |
description |
Fragmentation of the sea ice cover by ocean waves is an important mechanism impacting ice evolution. Fractured ice is more sensitive to melt, leading to a local reduction in ice concentration, facilitating wave propagation. A positive feedback loop, accelerating sea ice retreat, is then introduced. Despite recent efforts to incorporate this process and the resulting floe size distribution (FSD) into the sea ice components of global climate models (GCMs), the physics governing ice breakup under wave action remains poorly understood and its parametrisation highly simplified. We propose a two-dimensional numerical model of wave-induced sea ice breakup to estimate the FSD resulting from repeated fracture events. This model, based on linear water wave theory and visco-elastic sea ice rheology, solves for the scattering of an incoming time-harmonic wave by the ice cover and derives the corresponding strain field. Fracture occurs when the strain exceeds an empirical threshold. The geometry is then updated for the next iteration of the breakup procedure. The resulting FSD is analysed for both monochromatic and polychromatic forcings. For the latter results, FSDs obtained for discrete frequencies are combined following a prescribed wave spectrum. We find that under realistic wave forcing, lognormal FSDs emerge consistently in a large variety of model configurations. Care is taken to evaluate the statistical significance of this finding. This result contrasts with the power law FSD behaviour often assumed by modellers. We discuss the properties of these modelled distributions with respect to the ice rheological properties and the forcing waves. The projected output can be used to improve empirical parametrisations used to couple sea ice and ocean wave GCM components. |
format |
Text |
author |
Mokus, Nicolas Guillaume Alexandre Montiel, Fabien |
spellingShingle |
Mokus, Nicolas Guillaume Alexandre Montiel, Fabien Wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study |
author_facet |
Mokus, Nicolas Guillaume Alexandre Montiel, Fabien |
author_sort |
Mokus, Nicolas Guillaume Alexandre |
title |
Wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study |
title_short |
Wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study |
title_full |
Wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study |
title_fullStr |
Wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study |
title_full_unstemmed |
Wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study |
title_sort |
wave-triggered breakup in the marginal ice zone generates lognormal floe size distributions: a simulation study |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-16-4447-2022 https://tc.copernicus.org/articles/16/4447/2022/ |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-16-4447-2022 https://tc.copernicus.org/articles/16/4447/2022/ |
op_doi |
https://doi.org/10.5194/tc-16-4447-2022 |
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The Cryosphere |
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16 |
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10 |
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4447 |
op_container_end_page |
4472 |
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1766191014156959744 |