Radiometric calibration of the SnowSAR images of sub-artic open tundra watershed in Canada

The quantity of water stored in snow is an important subject of study for many Earth science fields, concerned with the assessment of the natural distribution of water in time and space. The ESA project COld REgions Hydrology High- resolution Observatory (CoReH₂O) [1] aims at measuring the characteristics of the cryosphere, especially the snow cover, at unprecedented levels of spatial resolution, coverage and absolute accuracy. Many in situ measurements (manual snow pit measurements, snow surveys), as well as data acquired with a scatterometer and a comprehensive set of ground and meteorological parameters are collected for the project. The necessity of a wide and continuous time series measurements pushes to the collection of airborne SAR images with high spatial resolution , acquired over snow-covered areas during extended time periods. The SnowSAR instrument, a dual frequency airborne SAR, has been developed to fulfill this goal. A highly accurate radiometric calibration is required for SnowSAR images, to allow for comparisons with data acquired by other sensors and over long periods of time. This paper shows a detailed analysis of the calibration phase, which represents the last step of the SnowSAR processing chain. In particular, the analysis is conducted on SnowSAR data acquired over a sub-artic open tundra watershed in the Northwest Territories, Canada, during two missions in March and April 2013.