CoReH2O – A dual-frequency SAR mission for improved snow and ice observations

The satellite mission COld REgions Hydrology High-resolution Observatory (CoReH2O) has been selected by the European Space Agency for scientific and technical feasibility studies within the Earth Explorer Programme. The mission aims at closing major gaps in present snow and ice observations that are needed to advance our understanding of the role of snow and ice in the climate system and to improve the knowledge and prediction of the water cycle in cold environment. CoReH2O will provide spatially detailed observations of extent, water equivalent and melting state of the seasonal snow cover, of snow accumulation and diagenetic facies on glaciers, of permafrost features, and of sea ice properties with emphasis on new ice formation and snow burden. The observations will be applied for initializing and validating high resolution models of surface/atmosphere interaction and hydrological processes in snow and ice covered regions. Two mission operation phases are proposed. During the first two years the satellite will revisit well equipped test sites and other key regions in a three days repeat cycle in order to validate satellite-derived snow and ice products and to advance cryosphere process models and surface/atmosphere interaction models. During the second mission phase full coverage of the cryosphere will be provided within 15-days to enable global studies.
The measurement concept is based on the high sensitivity of Ku- and X-band backscatter to physical properties of snow and ice. The proposed sensor is a dual frequency SAR, operating at 17 GHz and 9.6 GHz, VV and VH polarizations, with about 50 m spatial resolution. The dual frequency, dual polarization approach enables the decomposition of the scattering signal into surface and volume contributions to separate the snow pack signal from the background target. Ongoing preparatory activities for the mission include improvements and testing of radar backscatter models for snow and ice, the development of algorithms for retrieval of snow physical properties, and studies on assimilation of satellite snow products in cyrospheric process models. In addition, several experimental campaigns with in situ and airborne scatterometers were carried out in the winter 2006/07 and are planned for winter 2007/08 to support the development and validation of retrieval algorithms.