Reanalysis of Skylab S-194 L-band Data in View of Validating Sea Surface Roughness Corrections for Salinity Measurements from Space
Abstract
Of the satellite radiometer sensors, there has been only one instrument that provides any heritage at L-band: the Skylab S-194 instrument that operated in the 1970s. From an analysis of S-194 brightness temperature (Tb) sensitivity to SSS, SST and wind speed, Lerner & Hollinger (1976) concluded that the wind speed dependence of L-band brightness temperature at nadir is about 0.16 K/knot. This is almost four times higher than what is predicted by recently developed sea surface emissivity models at L-band and twice the experimental value reported during the Bering Sea Experiments. To investigate the possible reasons for such discrepancies, two data sets acquired by the S-194 Skylab instrument from 1973-1974 missions are used in the present paper in conjunction with products from climate model reanalysis projects as ancillary data. The re-analyses shows that it is very likely that Lerner & Hollinger overpredicted the quasi-linear wind speed dependence of L-band sea surface emissivity at nadir by a factor of about 2, main discrepancies being due to different wind speed data used in the analysis. Still, we found that emissivity models for the foam free sea surface based on the small perturbation method underestimate the roughness impact at nadir by a factor of 2. Including the foam impact cannot explain all the differences.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 25, 2005
- Accession Number
- ADA451491
Entities
People
- Bertrand Chapron
- Doug Vandemark
- Joseph Tenerelli
- Nicolas Reul