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| Titel |
Influence of sea ice lead-width distribution on turbulent heat transfer between the ocean and the atmosphere |
| VerfasserIn |
S. Marcq, J. Weiss |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 6, no. 1 ; Nr. 6, no. 1 (2012-02-02), S.143-156 |
| Datensatznummer |
250003381
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| Publikation (Nr.) |
 copernicus.org/tc-6-143-2012.pdf |
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| Zusammenfassung |
| Leads are linear-like structures of open water within the sea ice cover that
develop as the result of fracturing due to divergence or shear. Through
leads, air and water come into contact and directly exchange latent and
sensible heat through convective processes driven by the large temperature
and moisture differences between them. In the central Arctic, leads only
cover 1 to 2% of the ocean during winter, but account for more than 70% of
the upward heat fluxes. Furthermore, narrow leads (several meters) are more
than twice as efficient at transmitting turbulent heat than larger ones
(several hundreds of meters). We show that lead widths are power law
distributed, P(X)~X−a with a>1, down to very small spatial scales
(20 m or below). This implies that the open water fraction is by
far dominated by very small leads. Using two classical formulations, which
provide first order turbulence closure for the fetch-dependence of heat
fluxes, we find that the mean heat fluxes (sensible and latent) over open
water are up to 55% larger when considering the lead-width distribution
obtained from a SPOT satellite image of the ice cover, compared to the
situation where the open water fraction constitutes one unique large lead and
the rest of the area is covered by ice, as it is usually considered in
climate models at the grid scale. This difference may be even larger if we
assume that the power law scaling of lead widths extends down to smaller
(~1 m) scales. Such estimations may be a first step towards a
subgrid scale parameterization of the spatial distribution of open water for
heat fluxes calculations in ocean/sea ice coupled models. |
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