Although SMOS was launched in November 2009, the sea surface salinity maps retrieved from SMOS brightness temperature images have not yet achieved the mission requirements. Strong spatio-temporal biases prevent consistent analysis of global datasets acquired at several week intervals. Characterization and mitigation of instrumental and model biases are of primary importance.
The systematic error correction strategy implemented in the SMOS operational processing chain mixes all kind of biases, namely related to the antenna patterns, the antenna losses, the foreign source imperfect corrections, or the errors in the forward model used for geophysical parameter inversion.
This practical strategy prevents consistent calibration error diagnostic or forward model improvement tasks. An alternative strategy which separates the different systematic error contributions and provides higher stability of the estimates is required and has recently been proposed. It allows diagnosis of the systematic (constant with time) TB errors in the antenna frame, with no impact of forward model errors.