General SMOSIce project description

The aim of the SMOSIce study is to develop, improve and validate algorithms for sea ice thickness retrieval from the 1.4 GHz (L-band) data of the European Space Agency's (ESA) Soil Moisture and Ocean Salinity (SMOS) mission. SMOS payload is the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) measuring the brightness temperature at a range of incidence angles and at different polarizations.

Electromagnetic radiation with wavelengths of 20 cm can emerge from deep inside the sea ice layer. The attenuation mainly depends on the relative brine volume which is a function of ice bulk salinity and temperature. The penetration depth is up to 1.5m for cold low-salinity ice and reduces to a few centimeters for saline sea ice at high temperatures. The potential to derive the ice thickness from L-band radiometry thus depends on sea ice temperature and salinity.

A sea ice emissivity model is an integral part for the retrieval of ice thickness from SMOS measurements. The most simple setup consists of a three layer (ocean-ice-atmosphere) dielectric slab with plane-parallel specular surfaces (Kaleschke et al.,2010). The dielectric properties are parameterized as a function of the bulk ice salinity and temperature. The sea ice bulk salinity and ice surface temperature will be taken either from auxiliary measurements or will be parameterized. One main objective of the SMOSIce study is to determine the best solution to define the Algorithm Theoretical Basis Documents (ATBD) for SMOS sea ice retrieval.

Finally, a SMOS sea ice product will be generated and assessed using independent ice thickness measurements. These will include in-situ observations, electromagnetic induction (EM) measurements, and estimates based on infrared and SAR satellite data.

SMOSIce project partners

First results

SMOS provides daily coverage of the polar regions with a resolution of about 35 km and can be used to measure sea ice thickness up to half a meter. The ice thickness derived from SMOS agrees with the ice thickness from thermal infrared MODIS images with 10cm standard deviation. SMOS thickness retrieval is well feasible and practical under ideal cold conditions. Changes in ice concentration and ice temperature, as well as the snow thickness are the largest uncertainties which are neglected for the first prototype of a retrieval algorithm.

Sea ice thickness during the Arctic freeze-up as seen by SMOS

SMOSIce User Workshop

A workshop to present the SMOS ice thickness product, the scientific and technical outcome of the study will take place at the KlimaCampus of the University of Hamburg, on 17 Feb 2012. Potential participants are sea ice remote sensing, modelers, and assimilation experts, as well as representatives from operational ice services and international projects (e.g. CliC, CCI) and potential data users. Contributions, conclusions and recommendations from the participants will be compiled in a workshop report.

Workshop details

• Date: 17 Feb 2012
• Time: 9:00-17:00

• Place: Institute of Oceanography, University of Hamburg

• Registration: until Jan 1, 2012 by email to Xiangshan Tian-Kunze
• Workshop fee: none

Technical programme

• General introduction by Yann Kerr
• Algorithm
• Validation

References

• Kaleschke, L., Maaß, N., Haas, C., Hendricks, S., Heygster, G., and Tonboe, R. T.: A sea-ice thickness retrieval model for 1.4 GHz radiometry and application to airborne measurements over low salinity sea-ice, The Cryosphere, 4, 583-592, doi:10.5194/tc-4-583-2010, 2010.