Thickness of thin sea ice


The thickness of thin sea ice (SIT) is daily retrieved from observations of the L-band microwave sensor SMOS (Soil Moisture and Ocean Salinity). Horizontal and vertical polarized brightness temperatures in the incidence angle range of 40° to 50° are averaged. The ice thickness is then inferred from the polarization difference and the intensity using an empirical method (Huntemann et al., 2014).

Thin sea ice occurs during the freezing season. In the melting season, the thickness of sea ice is highly variable and the emission properties in the microwave 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.

Each day of ice thickness data product are calculated twice to ensure that all swath files were available in the archived product. First processing is done directly on the next day with only about 7 hours delay. At this time it can happen that not all swath files are available and another processing of the same day is initiated 23 hours later. In more than 50% of the time the first processing does not include all swath but usually provides sufficient coverage for Arctic and Antarctic regions.

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).


Data Archive

All data can be found in the Data Archive. To quickly browse the dataset, please have a look at the Data Browser.

How to cite

Please help maintaining this service by properly citing and acknowledging if you use the data for publications:

Huntemann, M., Heygster, G., Kaleschke, L., Krumpen, T., Mäkynen, M., and Drusch, M.: Empirical sea ice thickness retrieval during the freeze-up period from SMOS high incident angle observations, The Cryosphere, 8, 439-451, doi:10.5194/tc-8-439-2014, 2014.


For questions regarding the data please contact Gunnar Spreen, Marcus Huntemann, or Georg Heygster.
For questions related to the website and data-browser please contact Malte Gerken.

Institute of Environmental Physics, University of Bremen, Germany.

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