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| Pivaev, P. D.; Kudryavtsev, V. N.; Balashova, E. A.; Chapron, Bertrand. |
| Purpose. The aim of the article is to study manifestations of the underwater topography features in the northern part of the White Sea in the images made by the spaceborn synthetic aperture radars (SAR) Sentinel-1A, Sentinel-1B. Methods and Results. In the SAR images, the bottom features are revealed as bright and dark brightness anomalies. The anomalies were observed at the wind speed ranging from 2.6 to 10.8 m/s, and became reverse (bright anomalies turned dark and vice versa), when a tidal current changed its direction. It is shown that the observed SAR imagery contrasts correlate to divergence of a current formed by interaction of a tidal flow with the bottom topography inhomogeneities. The simulated SAR contrasts agree with the observations, and... |
| Tipo: Text |
Palavras-chave: Bottom topography; Sentinel-1; SAR; Wave breaking; Current divergence. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00648/75989/76890.pdf |
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| Yurovsky, Yu. Yu.; Kudryavtsev, V. N.; Chapron, Bertrand. |
| Results of joint radar and video observations from the Black Sea Research platform are presented. Ka-band dual-copolarized (VV and HH) radar was used for measurements of backscattering cross-section and Doppler shifts. The radar footprint was observed by video camera, which was strictly synchronized with the radar. The total coverage of the radar footprint by bright features are computed using measured radar angular antenna pattern. Large foaming breaking waves resolved by the radar footprint are analyzed individually. Active phase of breaking wave process is accompanied by short intensive spike in radar backscattering. During the spike, the polarization ratio (HH/VV) approaches 1, indicating specular mechanism in backscattering from disturbed water mass... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00437/54828/56290.pdf |
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| Yurovsky, Yu. Yu.; Kudryavtsev, V. N.; Grodsky, S. A.; Chapron, Bertrand. |
| Field data taken from the Black Sea Research platform during 2009-2015 are used to develop a dual-co-polarized (VV and HH) empirical model for the sea surface normalized radar cross-section (NRCS) and Doppler Velocity (DV) in the Ka-band. A fitting function for the NRCS is the standard truncated Fourier series in azimuth with polynomial coefficients dependent on incidence angle and wind speed. The data are corrected for the angular antenna pattern, which is measured in special calibration procedures. The resulting NRCS model is consistent with other rare Ka-band measurements and agrees well with Ku-band geophysical model functions, in contrast with previously proposed Ka-band models. Surface is subtracted from measured DV using either propeller current... |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00437/54829/56288.pdf |
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