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Fois F.,Technical University of Delft | Hoogeboom P.,Technical University of Delft | Le Chevalier F.,Technical University of Delft | Stoffelen A.,KNMI Koninklijk Nederlands Meteorologisch Instituut
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2014

In this paper, we present a survey of some of the most common analytical approximate models that are used to describe the microwave sea surface scattering. The main strengths and weaknesses of the various methods are identified and critically discussed. Such models combine an adequate sea surface description with advanced electromagnetic theories to simulate both monostatic and bistatic scattering for a wide range of wind speeds, radar frequencies, incidence angles, different polarizations and arbitrary radar look direction with respect to the wind direction. Theoretical calculations for co-polar signals in C-band and Ku-band are in good overall agreement with the experimental data represented by the empirical models, CMOD5 and NSCAT, with the exception of HH-polarization at high incidence angles (above 40°). A parametric analysis on the sea surface spectrum, will demonstrate that the discrepancy between the measured and the simulated HH normalized radar cross-sections, is only in part due to the inefficiency of the spectrum and mostly due to additional scattering contribution from breaking waves, not taken into account by the most common analytical scattering theories. © 2014 IEEE.


Fois F.,Technical University of Delft | Hoogeboom P.,Technical University of Delft | Le Chevalier F.,Technical University of Delft | Stoffelen A.,KNMI Koninklijk Nederlands Meteorologisch Instituut
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2014

The growing interest in achieving a better understanding of the physics that governs the cross-polar scattering of microwave radiation from ocean is triggered by recent measurement campaigns over hurricanes performed by NOAA Hurricane-Hunter winds and RADARSAT-2 [1]. From this data set the cross-polarized signals showed no evident loss of sensitivity as the wind-speed increased from 20 m/s up to 45 m/s. On the contrary C-band co-polar backscatter suffered from problems of incidence and azimuth angle-dependent signal saturations and dampening which makes it weakly sensitive above 25 m/s. On the basis of these considerations there are good reasons to think that the cross-polarized data can be a valuable tool for the retrieval of strong-to-severe wind speeds for future scatterometers. In this paper we present a physical scattering model based on the Small Slope Approximation theory [2] in conjunction with the Vector Radiative Transfer Theory [3] to describe the behavior of cross-polar scattering from ocean as function of the wind-speed and direction. Numerical results will be compared with real data from RADARSAT-2 and the brand new empirical Geophysical Model Function GMF-VH [1]. © 2014 IEEE.


Fois F.,Technical University of Delft | Hoogeboom P.,Technical University of Delft | Le Chevalier F.,Technical University of Delft | Stoffelen A.,KNMI Koninklijk Nederlands Meteorologisch Instituut
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2015

The present paper proposes an innovative mission concept for a C-band fan-beam wind scatterometer with both ocean wind vector and ocean current vector measurement capability on a global scale. © 2015 IEEE.


De Vries J.,Dutch Space B V | Hoogeveen R.,SRON Netherlands Institute for Space Research | Voors R.,Dutch Space B V | Kleipool Q.,KNMI Koninklijk Nederlands Meteorologisch Instituut | And 6 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012

TROPOMI is the sun backscatter trace gas instrument on ESA's Sentinel-5 precursor satellite. TROPOMI builds upon a rich heritage from similar instruments, the main ones being SCIAMACHY on ESA's ENVISAT and OMI on NASA's AURA satellite. This paper explains how the technology from the heritage instruments evolved, considering high level design aspects such as geometry for Earth and sun viewing, polarization treatment, spectral calibration and whisk- or push-broom concept and leading to the TROPOMI concept. © 2012 IEEE.

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