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Sea ice thickness information is essential for safe and environmentally friendly marine operations in polar waters. It is required for the design of icebreakers, offshore structures, and port facilities, as well as supporting information for ship routing through ice and ice forecasting.
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Sea ice thickness is also required for observations and modelling of climate change in the polar regions. Together with ice extent, sea ice thickness is considered an indicator for climate change, and is used to improve and validate numerical models to predict the future development of the global sea ice cover.
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Despite its importance, there are only few ice thickness measurements available, and most can only be gathered with huge logistic efforts, e.g. by nuclear submarines or icebreaking research vessels for the deployment of ice profiling sonars or autonomous underwater vehicles (AUVs). The Alfred Wegener Institute for Polar and Marine Research (AWI) is therefore developing alternative methods operable by helicopters, airplanes and satellites
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The most established ice profiling technique is electromagnetic (EM) ice thickness sounding. This can be operated from helicopters, allowing easy, flexible, and near-real-time ice thickness surveys. By use of land stations in North America and ice camps, we have established systematic ice thickness surveys for climate studies and the oil industry in North America. The technique has been and can be used also from board icebreakers and offshore structures to be used for monitoring of ice parameters relevant for ice load estimates in engineering projects. We use Envisat and Radarsat SAR imagery to extrapolate our measurements regionally, and to develop new algorithms for the retrieval of ice parameters from SAR data.
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Most recent developments include adaptation of the EM method to AWI’s polar research aircrafts, as well as operation of ASIRAS, an airborne synthetic-aperture radar altimeter also implemented on ESA’s forthcoming CryoSat mission. ASIRAS is therefore extensively used for the pre- and post-launch validation of CryoSat, in close cooperation and with support of ESA.
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The ultimate goal of ice thickness measurements are systematic observations of regional and seasonal, interannual, and decadal thickness variations. These can only be obtained from satellites like CryoSat. Therefore, AWI is closely involved with the mission and will use its data in a wide range of ocean-ice-atmosphere studies as well as for modelling and predictions of future climate developments in the polar regions.
