Interannual and decadal variability of sea ice drift, concentration and thickness in the Weddell Sea

• Main Author: Schwegmann, Sandra
• Other Authors: Lemke, Peter, Gerdes, Rüdiger
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2012
• Subjects: Sea ice; Weddell Sea; drift; concentration; thickness; volume; NCEP; FESOM; sea ice-atmosphere interaction; 550; 550 Earth sciences and geology; ddc:550; Antarctic; Antarctic Peninsula; The Antarctic; Weddell; Antarc*
• Online Access: https://media.suub.uni-bremen.de/handle/elib/340; https://nbn-resolving.org/urn:nbn:de:gbv:46-00102689-14

Sea ice concentrations in the Weddell Sea are subject to regional climate variability. The magnitude and origin of local trends in the sea ice coverage were studied using the bootstrap algorithm sea ice concentration data from the NSIDC for 1979-2006. The impact of atmospheric forcing such as air temperature, wind speed, sea level pressure and cloud coverage, gained from NCEP/NCAR reanalysis, was assessed by analyzing correlation coefficients between the respective atmospheric component and the sea ice concentrations. In addition, the variability of sea ice drift was analyzed using the Polar Pathfinder sea ice motion vectors, and the correlation with sea ice concentration was tested after an assessment of the product s uncertainties. The connection to the variability of sea ice thicknesses was derived by model simulations from the Finite Element Sea ice-Ocean Model (FESOM). It was found that sea ice concentrations increased in the eastern and decreased in the western Weddell Sea, predominantly in the marginal sea ice zone. There, and in coastal regions, temperatures are strongly negatively correlated to sea ice concentrations, whereas in the central Weddell Sea, mostly a positive correlation was assessed, especially during winter. From analyses of the wind field it was found that the prevailing westerlies at the Antarctic Peninsula frequently show a shift towards the south. The enhanced southward winds are expected to bring warmer air into the western and central Weddell Sea and are further expected to redistribute the sea ice from the west into the central and eastern regions. This would increase the sea ice concentrations in the central Weddell Sea due to enhanced compactness, although temperatures are increasing. The correlation between sea ice concentrations and sea ice drift is only robust for the central Weddell Sea, where both parameters are mainly anti-correlated. Hence, strong sea ice drift is connected to lower sea ice concentrations and vice versa. This finding is consistent with the connection to the ...