Spaceborne radiometric measurements of the L bandbrightness temperature over the oceans make it possible to estimate sea surfacesalinity. However, Faraday rotation in the ionosphere disturbs the signalsand must be corrected. Two different ways of assessing the disturbance directlyfrom the radiometric measurements, and hence enabling a correction for theeffect, are being discussed. Also, a method, which aims at circumventing theproblem by using the first Stokes parameter in the salinity retrieval, isbeing discussed.