Seasonal evolution of an ice-shelf influenced fast-ice regime, derived from an autonomous thermistor chain

• Main Authors: Hoppmann, Mario, Nicolaus, Marcel, Paul, Stephan, Hunkeler, Priska, Heil, Petra, Behrens, Lisa Katharina, König-Langlo, Gert, Gerdes, Rüdiger
• Format: Conference Object
• Language: unknown
• Published: 2014
• Subjects: Antarc*; Antarctic; Antarctica; Ice Shelf; Sea ice; Weddell Sea
• Online Access: https://epic.awi.de/id/eprint/40738/; https://epic.awi.de/id/eprint/40738/1/DFG_Dresden_2014_small.pdf; https://hdl.handle.net/10013/epic.47771; https://hdl.handle.net/10013/epic.47771.d001

The overall goal of this study is to characterize the seasonal evolution of an Antarctic coa- stal, ice-shelf influenced fast-ice regime with an autonomous thermistor chain Background: The formation of ice crystals in supercooled water at depth is a manifestation of basal melt pro- cesses in the ice-shelf cavity. These ice platelets accumulate in large amounts below sea ice to form a porous layer. This phenomenon is of crucial importance for fast-ice properties and ecosystems in coastal Antarctica, but information about its formation and spatio-temporal variability is still sparse. This is at least partly attributed to the lack of suitable methodology. Method: We obtained a 15 month long time-series of sea-ice temperature profiles on the fast ice of Atka Bay, a coastal sea-ice regime in the eastern Weddell Sea. We used a thermistor chain with the additional capability of actively heating its thermistor elements, taking advantage of the different thermal characteristics of the surrounding meda. Despite the rising interest in this kind of instrument, its full potential has not been assessed yet. Results: Calculating the basal energy budget, we find a heat flux into the ocean which accounts for 18 % of solid sea-ice growth. This corresponds to a platelet layer ice-volume fraction of 18 %, which is also confirmed by model simulations and agrees well with a previous study at the same location. In addition, this study confirmed the seasonal evolution of the platelet layer found in the previous year (Hoppmann et al. 2014). Ocean/ice-shelf interaction dominated the overall (solid+loose) sea-ice thickness gain by effectively contributing 1.28 m, or 61 %, of the total sea-ice growth. Finally we use this unique dataset to assess the potential of this relatively new instrument design, highlighting its advantages and pointing out its caveats.