L-Band Sea Surface Emissivity: Preliminary Results Of The WISE-2000 Campaign And Its Application To Salinity Retrieval In the SMOS Mission

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Defense date2003-06-30
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Abstract
Soil moisture and ocean salinity at surface level can be measured by passive
microwave remote sensing at L-band. To provide global coverage data of soil moisture
and ocean salinity with three-day revisit time, the Earth Explorer Opportunity Mission
SMOS (Soil Moisture and Ocean Salinity) was selected by ESA (European Space Agency)
in May 1999. SMOS' single payload is a Y-shaped 2-D aperture synthesis interferometric
radiometer called MIRAS (Microwave Imaging Radiometer by Aperture Synthesis).
SMOS presents some particular imaging peculiarities: variation of incidence and azimuth
angles, different radiometric sensitivity and accuracy at each direction (pixels), and
geometric polarization mixing. Therefore, the accuracy of the geophysical parameter
retrieval depends on the knowledge of the angular dependence of the emissivity over a
wide range of incidence and azimuth angles. The accuracy of the sea surface salinity
retrievals depends on our capability to correct the wind-induced variation of the brightness
temperatures. To better understand wind effects, ESA sponsored the WInd and Salinity
Experiment 2000 (WISE-2000) from November 15, 2000, to January 16, 2001, in the
Casablanca oil rig, at 40 km off the coast of Tarragona (Spain). This paper is divided into
two parts. First, it presents the derived sensitivities of the brightness temperatures at vertical and horizontal polarizations with wind speed, and compares to Hollinger's
measurements and numerical simulations. Second, these results are applied to the SMOS
sea surface salinity (SSS) retrieval problem for different tracks within the swath. It is
shown that, except for low SSS and sea surface temperature (SST), the retrieved SSS has a RMS error of approximately 1 psu in one satellite pass.
CitationA. Camps, I. Corbella, M. Vall-llossera, N. Duffo, F. Torres, R. Villarino, L. Enrique, F. Julbé, J. Font, A. Julià, C. Gabarró, J. Etcheto, J. Boutin, A. Weill, V. Caselles, E. Rubio, P. Wursteisen, . (2003). L-Band Sea Surface Emissivity: Preliminary Results Of The WISE-2000 Campaign And Its Application To Salinity Retrieval In the SMOS Mission. Radio science, 38 (3): 36-1-36-8. ISSN:0048-6604
ISSN0048-6604
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