The seasonal cycle of an ice-shelf influenced fast-ice cover, derived from thermistor-chain temperature profiles

• Main Authors: Hoppmann, Mario, Nicolaus, Marcel
• Format: Conference Object
• Language: unknown
• Published: 2014
• Subjects: Antarc*; Antarctica; Ice Shelf; Sea ice; Weddell Sea
• Online Access: https://epic.awi.de/id/eprint/39100/; https://epic.awi.de/id/eprint/39100/2/FRISP_2014_small.pdf; https://hdl.handle.net/10013/epic.46335; https://hdl.handle.net/10013/epic.46335.d002

The formation of ice platelets in supercooled water is a manifestation of basal melt processes in the cavity. These crystals accumulate in large amounts below the fast ice to form a porous layer. Despite its importance for sea ice and ecosystems in coastal Antarctica, information about its formation and spatio-temporal variability is 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 medium. Despite the rising interest in this kind of instrument, its full potential has not been assessed yet. Calculating the basal energy budget, we find a negative oceanic heat flux which accounts for 18 % of seaice 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. Ice platelets dominated the overall 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 (Jackson 2013), highlighting its advantages and pointing out its caveats.