ETA Model Simulations and AMSR Images to Study an Event of Polynya at Terra Nova Bay, Antarctica
In the Terra Nova Bay (TNB) region, the near-surface winds are persistently strong (in particular during the winter season) and blow offshore with a high degree of directional constancy. This region is also known as a preferential zone of coastal polynyas. Polynyas are recurring areas of open waters...
| Main Authors: | , |
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| Other Authors: | , |
| Format: | Book Part |
| Language: | English |
| Published: |
A. Berger, F. Mesinger, D. Sijacki, Springer-Verlag
2012
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| Subjects: | |
| Online Access: | http://hdl.handle.net/11380/646848 https://doi.org/10.1007/978-3-7091-0973-1_16 |
| Summary: | In the Terra Nova Bay (TNB) region, the near-surface winds are persistently strong (in particular during the winter season) and blow offshore with a high degree of directional constancy. This region is also known as a preferential zone of coastal polynyas. Polynyas are recurring areas of open waters/thin ice surrounded by an ice covered sea. Coastal polynyas form along ice bound coasts; they are believed to be due to strong and persistent offshore winds and/or ocean currents which drive the sea ice away. As the ice is removed from the region of origin, open water is exposed, refrozen and the new ice is pushed away, so that coastal polynyas provide a source of new ice production. The horizontal surface temperature differences among the land ice, water and sea ice are strong, because the open water is close to the freezing point (-1.8 °C for typical salt water). The energy exchange between the ocean and the atmosphere in the Antarctic marginal sea ice zone is influenced by the extent of sea-ice cover. While the sea ice acts as insulation, a direct contact is established in areas with open water and intense energy exchanges occur, due to the large difference of temperature between the water and the air above it. This implies that the polynyas are areas where the ocean exchanges energy with the atmosphere and as a result they have an effect on the polar meteorology/climate. In Antarctica, the atmospheric numerical models which provide good results at the mid latitude, are put to the test, because the observations are scarce, the initial and boundary conditions are sometimes inadequate, complex terrain, sea ice and polynyas are present. Here, the numerical simulation of a real event of coastal polynya at TNB is shown, using a recent version of the Eta Model. The horizontal resolution is approximately 20 km and 50 level are considered in the vertical up to 25 hPa. Initial and boundary conditions are obtained from ECMWF analyses. The event, occurred from 12 to 18 July 2006, was selected by the analysis of the sequence ... |
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