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Summary of Proposal OCE1972

TitleInvestigation of sea-ice and snow properties in the Weddell Sea, Antarctica, during winter
Investigator Willmes, Sascha - University of Trier, Environmental meteorology
Team Member
Mr. Paul, Stephan - University of Trier, Environmental meteorology
Mr. Hoppmann, Mario - Alfred-Wegener Institute Bremerhaven, Sea-ice physics
Dr. Nicolaus, Marcel - Alfred-Wegener Institute Bremerhaven, Sea-ice physics
Dr. Kindermann, Lars - Alfred-Wegener Institute Bremerhaven, Observational Oceanography
Dr. Dierking, Wolfgang - Alfred-Wegener Institute Bremerhaven, Climate Sciences
SummaryThe physical properties of the sea ice and its snow cover in the Weddell Sea will be investigated at different ice stations. For a multi-day sea-ice station, these measurements will include sea-ice coring for in-situ measurements of temperature, salinity, density and texture; ground-based EM-measurements, which produce high resolution sea-ice thickness data; manual thickness measurements through drilling to obtain ratios of sea-ice freeboard, draft, and thickness; a variety of methods (depth soundings with probes, laser scanning, infrared photography) to obtain floe-scale snow depth and surface-roughness distributions. Measurements will be partially repeated if snowfall/blowing snow occur during ice stations. snow stratigraphy and physical snow properties from snow pits; sea-ice concentration using a 360 thermal imager. In addition, sea-ice mass balance buoys (IMB), snow depth buoys, and GPS buoys will be deployed on the sea ice, some combined with automatic weather stations (AWS). These buoys will measure and transmit various snow and sea-ice data also beyond the cruise. Finally, sea-ice thickness distributions will be measured along the cruise track by means of helicopter surveys carrying an EM-Bird. Additionally, information on the surface roughness will be obtained by airborne laser altimetry, and a nadir-looking aerial camera will document the general surface conditions. These measurements will be performed as often as possible in order to obtain a dense grid of measurements and will last about 2 hours per flight. Continuous visual observations of the sea ice cover and meteorological conditions will be made on an hourly basis from the ships bridge by trained observers. To support these observations, a camera system will be installed and maintained during the cruise. Shipboard measurements of snowfall will additionally provide information on precipitation frequency and intensity. For the project it is planned to use TSX images in combination with thermal infrared imagery and passive microwave data. TSX data (a combination of ScanSAR and StripMap) are used to resolve the differences between first- and second-year ice floes in the Weddell Sea and to detect the evolution of snow metamorphism from the marginal ice zone to the closed pack ice (Nicolaus et al., 2009). The potential and the problems of using TSX data for this application are examined by comparison with the extensive field data outlined above. Apart from the post-cruise analyses, TSX images will be a valuable tool to identify regions with strong brightness contrast that might subsequently be visited by helicopter to acquire field data which help to understand causes for such contrasts. FundingSituation The presented work is partly funded by the DFG within the priorityprogramme "Antarctic Research" under contracts HE 2740/12-1 and NI1096/2-1. Sascha Willmes is a Postdoc funded by the Universityof Trier (permanent, 50%) and by DFG (until Dec 2013, 50%). Marcel Nicolaus and Wolfgang Dierking are on permanentpositions at AWI. Mario Hoppmann and Stephan Paul hold a PhD position atAWI and Uni Trier, respectively, funded by the DFG (SIMBIS, He 2740/12, NI1092/2). Lars Kindermann is staff scientist at AWI.

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