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| Titel |
Influence of coastal polynyas on heat flux and sea ice production in the southwestern Weddell Sea |
| VerfasserIn |
Verena Haid, Ralph Timmermann, Lars Ebner, Guenther Heinemann |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250081333
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| Zusammenfassung |
| A coastal polynya occurs where off-shore winds cause the sea ice to drift away from the
coastline. The reduced or removed ice cover allows an almost unobstructed ocean-atmosphere
heat exchange and in the winter months very high ice production rates are induced.
Therefore, coastal polynyas are often referred to as ‘ice factories’.
With the Finite Element Sea ice-Ocean Model (FESOM) we investigate the coastal
polynyas in the southwestern Weddell Sea. The combination of a primitive-equation,
hydrostatic ocean model and a dynamic-thermodynamic sea ice model was set up with a
global, unstructured grid that features a horizontal resolution of up to 3 km along the
southwestern Weddell Sea coastline. The 37 depth levels have increased resolution
toward the surface. The model was initialized on 01/01/1980 with data from the Polar
Hydrographic Climatology and the boundary conditions were supplied by the NCEP/NCAR
Reanalysis.
Our analysis of the period 1990-2009 indicates that in an average winter season coastal
polynyas cover an area of 9000 km2 and facilitate an ocean-to-atmosphere heat transport of
370 W/m2, which splits into about 61% of sensible heat, 24% latent heat, 16% longwave
radiation and -1.5% shortwave radiation. The ocean provides 50 W/m2 by cooling the water
column, the rest is supplied from latent heat released in the process of 9 cm/d ice
production (accumulating to 1-
1011 m3/season). Interannual variability, however, is high.
An evaluation of additional simulations with three higher-resolution atmospheric
forcing dataset, including two regional configurations of the COSMO atmosphere
model, yields local differences but robustness and consistency on a larger scale. |
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