Publication

2005-05

English

http://archimer.ifremer.fr/doc/00000/10940/9268.pdf (Publisher's official version, 2.02 Mo)

2005 IEEE

Camps A¹, Vall-Ilossera M¹, Villarino R¹, Reul Nicolas², Chapron Bertrand², Corbella I¹, Duffo N¹, Torres F¹, Miranda Jj¹, Sabia R¹, Monerris A¹, Rodriguez R¹

1 : Univ Politecn Catalunya, Dept Signal Theory & Commun, E-08034 Barcelona, Spain.
2 : IFREMER, Dept Oceanog Phys & Spatiale, Lab Oceanog Spatiale, F-29280 Plouzane, France.

Ieee Transactions On Geoscience And Remote Sensing (0196-2892) (Ieee-inst Electrical Electronics Engineers Inc), 2005-05 , Vol. 43 , N. 5 , P. 925-937

28

Physical Oceanography

brightness temperature, emission, foam, microwave radiometry, salinity, sea

Sea surface salinity can be measured by microwave radiometry at L-band (1400-1427 MHz). This frequency is a compromise between sensitivity to the salinity, small atmospheric perturbation, and reasonable pixel resolution. The description of the ocean emission depends on two main factors: 1) the sea water permittivity, which is a function of salinity, temperature, and frequency, and 2) the sea surface state, which depends on the wind-induced wave spectrum, swell, and rain-induced roughness spectrum, and by the foam coverage and its emissivity. This study presents a simplified two-layer emission model for foam-covered water and the results of a controlled experiment to measure the foam emissivity as a function of salinity, foam thickness, incidence angle, and polarization. Experimental results are presented, and then compared to the two-layer foam emission model with the measured foam parameters used as input model parameters. At 37 psu salt water the foam-induced emissivity increase is -0.007 per millimeter of foam thickness (extrapolated to nadir), increasing with increasing incidence angles at vertical polarization, and decreasing with increasing incidence angles at horizontal polarization.