Sea ice thickness

Daily sea ice thickness (CryoSat-2)

Data of sea ice thickness is derived from the CryoSat-2, satellite of the European Space Agency (ESA). Launched in 2010, the polar-orbiting CryoSat was developed to measure thickness variations of polar ice masses, including glaciers and the great inland ice sheets of Greenland and Antarctica. Currently, changes are especially apparent in the Arctic sea ice. Thus, a major aim of the CryoSat mission is the determination of Arctic sea ice thickness. It is being planned to offer comparable data for the Antarctic.

With the CryoSat-2 radiometer the small portion of the ice/snow cover above the sea surface (surface elevation or freeboard) is measured and then transformed into ice thickness based on a several assumptions. The Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research works together with ESA in a collaborative project on the accuracy of the sea ice thickness data. The first freeboard and sea ice thickness maps resulting from this project are now available on this website: Deutsches CryoSat Projektbüro.

Data sets available for download here are only an outlook on the quality expected in the finalized data (Disclaimer). The data is also available via FTP. All relevant information about the AWI CryoSat-2 “Sea Ice Thickness Data Product” (PDF) is summarized in the following document.

FTP Data CryoSat-2
Wiki CryoSat-2
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Daily Thickness of Thin Sea Ice Maps (SMOS) - Uni Bremen

The thickness of thin sea ice is daily retrieved from observations of the L-band microwave sensor SMOS (Soil Moisture and Ocean Salinity) in the incidence angle range of 40° to 50°, horizontal and vertical polarization.

Thin sea ice occurs during the freezing season. In the melting season, the thickness of sea ice is highly variable. In addition, the emissivity properties change due to the wetness of the surface and occurrence of melt ponds in the Arctic. Therefore, thickness data are calculated only during the freezing season, that is from October to April in the Arctic and from March to September in the Antarctic. During the melting season, the procedure does not yield meaningful results.

As the resolution of SMOS at the used incidence angle range is about 40 km, only larger regions of thin ice will be retrieved correctly. The rim of thin ice shown in many cases not necessarily indicates thin ice, but can also be caused by the smearing effect (convolution) of the low resolution.

This service has been developed in the framework of the EU project SIDARUS. After completion of the SIDARUS project end 2013, the service is continued on a best effort base in the context of the Polar View and of the Arctic Regional Ocean Observing System (Arctic ROOS). For more information visit the website of University of Bremen.

The procedure and validation efforts are described in Huntemann et al. (2014) However, no warranty is given for the data presented on these pages.

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Daily Thickness of Thin Sea Ice Maps (SMOS) - Uni Bremen

The European Space Agency’s (ESA) Earth Explorer Mission SMOS has been launched in November 2009 with its primary objectives to globally observe soil moisture and ocean salinity from the brightness temperatures at 1.4 GHz (L-band). The retrieval of sea ice thickness became an important spin-off application and different methods for the retrieval have been developed. A validation with ground measurements showed the advantage of the AWI SMOS sea ice thickness product (previously called UH product) in comparison to the alternative product of the University of Bremen.

FTP Data SMOS
Wiki SMOS
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Weekly Sea Ice Thickness Maps based on CryoSat-2/SMOS Data Fusion

The combination of CryoSat-2 and SMOS data sets can be used to achieve improve sea ice thickness information and the update rate of Arctic wide maps. This is based on the fact that CryoSat-2 is designed for ice thickness retrieval for thicknesses above 1 meter while SMOS delivers accurate thin ice thickness information.

The combination of both datasets is based on a statistical approach (optimal interpolation), which merges weekly information from CryoSat-2 and SMOS from the Alfred Wegener Institute based on the respective uncertainties for different thickness classes. The joint product was developed within the ESA project SMOS+ Sea Ice.

A detailed algorithm description can be found here. An overview can be found in the publication of Kaleschke et al. (2015). The use of this product is based on similar terms and conditions than the CryoSat-2 data product (Disclaimer)

FTP Data CryoSat-2/SMOSa>
Wiki CryoSat-2/SMOS
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