Retrieval modeling and error sources for microwave remote sensing of ocean surface salinity

A set of geophysical error sources for the microwave remote sensing of ocean surface salinity have been examined. The error sources include the sea surface temperature, sea surface roughness, atmospheric gases, ionospheric Faraday rotation, and planetary and galatic emission sources. It is shown that the brightness temperature errors of a few Kelvin can be expected for most of these error sources. The key requirements for corrections are the knowledge accuracy of 0.5°C for the sea surface temperature (SST), 10°C for the surface air temperature, 0.2° accuracy for the Faraday rotation, and 0.3 m/s for the surface wind speed. The authors suggest the use of data products from AMSR-type instruments for the corrections of SST and liquid cloud water, the numerical weather analysis for the surface air temperature, and on-board radar and polarimetric radiometer channel for surface roughness and Faraday rotation. The most significant sky radiation is from the Sun. A careful design of the antenna is necessary to minimize the leakage of solar radiation or reflection into the antenna side lobe. The narrowband radiation from galatic hydrogen clouds is also significant, but can be corrected with an accurate radio sky survey or minimized with a notched (band-rejection) alter centered at 1.420 GHz in the receiver