Microwave Sea Surface Salinity (SSS) measurements can be performed by isolating the emissivity response to salinity changes from numerous geophysical effects, including surface temperature and wind waves. At L‐band frequencies (1 to 2 GHz), the sensitivity to SSS is sufficient but it falls off quickly as frequency is increased. Nevertheless, methods using higher microwave frequencies with much lower SSS sensitivity than at L band, can already be tested. In particular, combining 6 and 10 GHz data in vertical polarization efficiently minimizes sea surface roughness and thermal impacts. Using AMSR‐E data, the retrieved bi‐monthly maps of SSS at 0.5° resolution over the region of the Amazon plume show relative accuracy in‐line with the future L‐band dedicated mission objectives.
