Impact of the Sea Ice Floe Size Distribution on the Seasonal Evolution and Inter-annual Variability of Arctic Sea Ice.
Abstract
The sea ice cover of the Arctic ocean is composed of discrete areas of sea ice called floes. Climate models currently assume that these floes all have a uniform diameter of 300 m. Observations generally show that a truncated power law produces a good fit to floe size distribution data. A number of processes are functions of floe size: lateral melt rate; momentum transfer between the sea ice, ocean and atmosphere; and sea ice rheology. Floe size can change through thermodynamic processes such as lateral melting or through mechanical processes such as breaking from the strain resulting from external wave fields. Floe size is expected to be a particularly important parameter in the marginal ice zone, a region at the edge of the sea ice cover with between 15 and 80 % sea ice cover, since it can moderate air/ice/ocean exchanges of heat and momentum. Floe size is also expected both to moderate and be influenced by the impact of high wind speed and storm events on sea ice.
In this study we investigate two alternative floe size distribution models within a sea ice—ocean (CICE-NEMO) coupled framework: the first assumes floe size adopts a truncated power law distribution with a variable maximum floe size; the second is a prognostic floe size distribution where floe sizes are sorted into discrete categories. We present results to show that the use of a variable floe size distribution has non-uniform impacts on the sea ice cover, in particular enhancing melt within the MIZ relative to the melt in the pack ice. We also compare the impacts of these two modelling approaches on behaviours of interest including the seasonal sea ice retreat and inter-annual variability. Finally, we will explore the impact of floe size on sea ice-ocean mixed layer feedback processes.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C32B..04F
- Keywords:
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- 0738 Ice;
- CRYOSPHERE;
- 0750 Sea ice;
- CRYOSPHERE;
- 0766 Thermodynamics;
- CRYOSPHERE;
- 0774 Dynamics;
- CRYOSPHERE