Seasonal and interannual variability of landfast sea ice in Atka Bay, Weddell Sea, Antarctica
| Autor: | Marcel Nicolaus, Holger Schmithüsen, Mario Hoppmann, Stefanie Arndt, Alexander D. Fraser |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
lcsh:GE1-350
geography geography.geographical_feature_category 010504 meteorology & atmospheric sciences Freeboard lcsh:QE1-996.5 010502 geochemistry & geophysics Snow 01 natural sciences Monitoring program Ice shelf Atmosphere lcsh:Geology Oceanography Fast ice 13. Climate action Sea ice 14. Life underwater Bay Geology lcsh:Environmental sciences 0105 earth and related environmental sciences Earth-Surface Processes Water Science and Technology |
| Zdroj: | EPIC3The Cryosphere, Copernicus, 14, pp. 2775-2793 The Cryosphere, Vol 14, Pp 2775-2793 (2020) |
| ISSN: | 1994-0424 |
| Popis: | Landfast sea ice (fast ice) attached to Antarctic (near-)coastal elements is a critical component of the local physical and ecological systems. Through its direct coupling with the atmosphere and ocean, fast-ice properties are also a potential indicator of processes related to a changing climate. However, in situ fast-ice observations in Antarctica are extremely sparse because of logistical challenges and harsh environmental conditions. Since 2010, a monitoring program observing the seasonal evolution of fast ice in Atka Bay has been conducted as part of the Antarctic Fast Ice Network (AFIN). The bay is located on the northeastern edge of Ekström Ice Shelf in the eastern Weddell Sea, close to the German wintering station Neumayer III. A number of sampling sites have been regularly revisited each year between annual ice formation and breakup to obtain a continuous record of sea-ice and sub-ice platelet-layer thickness, as well as snow depth and freeboard across the bay. Here, we present the time series of these measurements over the last 9 years. Combining them with observations from the nearby Neumayer III meteorological observatory as well as auxiliary satellite images enables us to relate the seasonal and interannual fast-ice cycle to the factors that influence their evolution. On average, the annual consolidated fast-ice thickness at the end of the growth season is about 2 m, with a loose platelet layer of 4 m thickness beneath and 0.70 m thick snow on top. Results highlight the predominately seasonal character of the fast-ice regime in Atka Bay without a significant interannual trend in any of the observed variables over the 9-year observation period. Also, no changes are evident when comparing with sporadic measurements in the 1980s and 1990s. It is shown that strong easterly winds in the area govern the year-round snow distribution and also trigger the breakup of fast ice in the bay during summer months. Due to the substantial snow accumulation on the fast ice, a characteristic feature is frequent negative freeboard, associated flooding of the snow–ice interface, and a likely subsequent snow ice formation. The buoyant platelet layer beneath negates the snow weight to some extent, but snow thermodynamics is identified as the main driver of the energy and mass budgets for the fast-ice cover in Atka Bay. The new knowledge of the seasonal and interannual variability of fast-ice properties from the present study helps to improve our understanding of interactions between atmosphere, fast ice, ocean, and ice shelves in one of the key regions of Antarctica and calls for intensified multidisciplinary studies in this region. |
| Databáze: | OpenAIRE |
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