Journal ArticleDOI
Issues concerning the sea emissivity modeling at L band for retrieving surface salinity
TLDR
In this article, a two-scale sea surface emissivity model was used to simulate brightness temperature at L band (1.4 GHz) and the influence of wind speed on Tb with various parameterizations of the sea wave spectrum was explored.Abstract:
[1] In order to prepare the sea surface salinity (SSS) retrieval in the frame of the Soil Moisture and Ocean Salinity (SMOS) mission we conduct sensitivity studies to quantify uncertainties on simulated brightness temperatures (Tb) related to uncertainties on sea surface and scattering modeling. Using a two-scale sea surface emissivity model to simulate Tb at L band (1.4 GHz), we explore the influence on estimated SSS of the parameterization of the seawater permittivity, of the sea wave spectrum, of the choice of the two-scale cutoff wavelength, and of adding swell to the wind sea. Differences between Tb estimated with various existing permittivity models are up to 1.5 K. Therefore a better knowledge of the seawater permittivity at L band is required. The influence of wind speed on Tb simulated with various parameterizations of the sea wave spectrum differs by up to a factor of two; for a wind speed of 7 m s−1 the differences on estimated SSS is several psu depending on the sea wave spectral model taken, so that sea spectrum is a major source of uncertainty in models. We find no noticeable effect on simulated Tb when changing the two-scale cutoff wavelength and when adding swell to the wind sea for low to moderate incidence angles. The dependence of the wind-induced Tb on SST and SSS being weak, we assess the error in SSS estimated assuming that the wind speed influence is independent of SST and SSS. We find errors on estimated SSS up to 0.5 psu for 20°C variation in SST. Therefore this assumption would induce regional biases when applied to global measurements.read more
Citations
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Journal ArticleDOI
SMOS: The Challenging Sea Surface Salinity Measurement From Space
Jordi Font,Adriano Camps,Andrés Borges,Manuel Martin-Neira,Jacqueline Boutin,Nicolas Reul,Yann Kerr,Achim Hahne,Susanne Mecklenburg +8 more
TL;DR: In this article, an L-band microwave interferometric radiometer with aperture synthesis (MIRAS) is used to generate brightness temperature images, from which both geophysical variables are computed.
Journal ArticleDOI
The determination of surface salinity with the European SMOS space mission
TL;DR: Recent results obtained from several studies and field experiments that were part of the SMOS mission are presented, and issues still to be solved are highlighted.
Journal ArticleDOI
Overview of the SMOS Sea Surface Salinity Prototype Processor
S. Zine,Jacqueline Boutin,J. Font,Nicolas Reul,Philippe Waldteufel,Carolina Gabarró,Joseph Tenerelli,F. Petitcolin,Jean-Luc Vergely,Marco Talone,Steven Delwart +10 more
TL;DR: Results of tests of the L2SPP involving horizontally uniform scenes with no disturbing factors other than wind-induced surface roughness are presented, and the use of wind components, which typically exhibit Gaussian error distributions, may be preferred in the retrieval.
Journal ArticleDOI
First Assessment of SMOS Data Over Open Ocean: Part II—Sea Surface Salinity
TL;DR: Soil Moisture and Ocean Salinity (SMOS) sea surface salinity (SSS) retrieved during August 2010 from the European Space Agency SMOS processing is validated and deducing SSS maps at 200 km × 200 km, 10 days resolution with an accuracy of 0.2 pss at a global scale is not out of reach.
Journal ArticleDOI
An Improved Fast Microwave Water Emissivity Model
TL;DR: A new permittivity model is generated by using the measurements for fresh and salt water at frequencies between 1.4 and 410 GHz and it is called as FASTEM-4 in the Radiative Transfer for TIROS Operational Vertical Sounder model.
References
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Book
World ocean atlas
Sergeĭ Georgievich Gorshkov,Soviet Union. Voenno-Morskoĭ Flot,Glavnoe upravlenie navigat︠s︡ii i okeanografii Ministerstva oborony Sssr +2 more
Journal ArticleDOI
A unified directional spectrum for long and short wind-driven waves
TL;DR: In this article, a two-dimensional wave spectral model is proposed for the high and low-wavenumber regimes, which is based on the Joint North Sea Wave Project (JONSWAP) in the long-wave regime and on the work of Phillips [1985] and Kitaigorodskii [1973] at the high-wavenumbers.
Journal ArticleDOI
An improved model for the dielectric constant of sea water at microwave frequencies
TL;DR: In this article, the dielectric constant of sea water has been measured at S-band and L-band with a quoted uncertainty of tenths of a percent, and expressions are developed which will yield computations of brightness temperature having an error of no more than 0.3 K for an undisturbed sea at frequencies lower than X-band.
Journal ArticleDOI
An improved model for the dielectric constant of sea water at microwave frequencies
TL;DR: In this paper, the dielectric constant of sea water has been measured at S-band and L-band with a quoted uncertainty of tenths of a percent, and expressions are developed which will yield computations of brightness temperature having an error of no more than 0.3 K for an undisturbed sea at frequencies lower than X-band.
Journal ArticleDOI
Equations for Calculating the Dielectric Constant of Saline Water (Correspondence)
TL;DR: In this article, the dielectric constant of saline water was represented by an equation of the Debye form and the parameters for the parameters were given as functions of the water temperature and salinity.