Faraday rotation and the SMAP radiometer

Faraday rotation is an issue to be taken into account in remote sensing from space at L-band. This is especially so for a conical scanner such as SMAP with a focus on soil moisture because the rotation angle varies with position around the scan and because the angle retrieved over land is noisy. Examples are reported. This is part of research to determine the accuracy of the retrieval of the rotation angle and the optimum way to deal with Faraday rotation over land.