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).
All relevant information about the AWI CryoSat-2 “Sea Ice Thickness Data Product” is summarized in the following document.
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Daily Thickness of Thin Sea Ice Maps (SMOS)
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. Further SMOS
data are also available here at Hamburg University.
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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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 from the Alfred Wegener Institute and SMOS from the University of Hamburg based on the
respective uncertainties for different thickness classes. The joint product was developed by the University of
Hamburg and the Alfred Wegener Institute with 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)
How to cite? ↗
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