| Summary: | Ice shelves strongly impact coastal Antarctic sea ice through the formation of a sub-ice platelet layer. This matrix of intertwined individual ice crystals influences sea-ice properties, mass- and energy balance, and represents an important habitat for a unique ecosystem. A comprehensive understanding of this system and associated processes is still not well established due to logistical and methodological difficulties. The main aim of this thesis was to overcome these limitations by the detailed investigation of a sea-ice regime heavily influenced by a nearby ice shelf. An ongoing monitoring program was developed and realized on the landfast sea ice of Atka Bay, a small embayment in front of the Ekström Ice Shelf in the eastern Weddell Sea, Antarctica. By combining measurements of sea ice, ocean and atmosphere over a period of five years, this work revealed important information about the seasonal cycle of the sea ice, its properties, and how it is influenced by the presence of thick snow on the surface and a several meter thick platelet layer underneath. This study showed that the contribution of ocean/ice-shelf interaction dominated the total sea-ice production at Atka Bay, effectively accounting for up to 70 % of annual sea-ice growth. The total annual ice-platelet volume underlying Atka Bay fast ice was equivalent to more than one fifth of the annual basal melt volume under the Ekström Ice Shelf. This work also contributed to the advance of several innovative methodological approaches, which are expected to facilitate sea-ice research in the future: 1) thermistor chains with active heating to investigate sea-ice evolution and to identify the governing factors; 2) multi-frequency electromagnetic induction sounding for the retrieval of platelet-layer properties on a larger scale and 3) high-resolution X-band synthetic aperture radar imagery to investigate snow physical properties.
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