Landfast sea-ice and platelet-layer thickness and conductivity of Atka Bay, Antarctica, December 2012, supplement to: Hunkeler, Priska A; Hoppmann, Mario; Hendricks, Stefan; Kalscheuer, Thomas; Gerdes, Rüdiger (2016): A glimpse beneath Antarctic landfast sea ice: platelet-layer volume from multi-frequency electromagnetic induction sounding. Geophysical Research Letters, 43(1), 222-231

• Main Authors: Hunkeler, Priska A, Hoppmann, Mario, Hendricks, Stefan, Kalscheuer, Thomas, Gerdes, Rüdiger
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2015
• Subjects: Sea Ice Physics @ AWI AWI_SeaIce; Antarctic; Weddell Sea; Weddell; Atka; Antarc*; Antarctica; Ice Shelf; Ice Shelves; Sea ice
• Online Access: https://dx.doi.org/10.1594/pangaea.845535; https://doi.pangaea.de/10.1594/PANGAEA.845535

Ice shelves strongly impact coastal Antarctic sea-ice and the associated ecosystem through the formation of a sub-sea-ice platelet layer. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In this study, we applied a laterally-constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the landfast sea ice of Atka Bay, eastern Weddell Sea, in 2012. In addition to consistent fast-ice thickness and -conductivities along > 100 km transects; we present the first comprehensive, high resolution platelet-layer thickness and -conductivity dataset recorded on Antarctic sea ice. The reliability of the algorithm was confirmed by using synthetic data, and the inverted platelet-layer thicknesses agreed within the data uncertainty to drill-hole measurements. Ice-volume fractions were calculated from platelet-layer conductivities, revealing that an older and thicker platelet layer is denser and more compacted than a loosely attached, young platelet layer. The overall platelet-layer volume below Atka Bay fast ice suggests that the contribution of ocean/ice-shelf interaction to sea-ice volume in this region is even higher than previously thought. This study also implies that multi-frequency EM induction sounding is an effective approach in determining platelet layer volume on a larger scale than previously feasible. When applied to airborne multi-frequency EM, this method could provide a step towards an Antarctic-wide quantification of ocean/ice-shelf interaction.