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Provedor de dados:  ArchiMer
País:  France
Título:  Sea Surface Ka-Band Doppler Measurements: Analysis and Model Development
Autores:  Yurovsky, Yury
Kudryavtsev, Vladimir
Grodsky, Semyon
Chapron, Bertrand
Data:  2019-04
Ano:  2019
Palavras-chave:  Radar
Doppler shift
Doppler centroid
Sea surface current
Wind drift
Transfer function
Empirical model
Resumo:  Multi-year field measurements of sea surface Ka-band dual-co-polarized (vertical transmit–receive polarization (VV) and horizontal transmit–receive polarization (HH)) radar Doppler characteristics from an oceanographic platform in the Black Sea are presented. The Doppler centroid (DC) estimated using the first moment of 5 min averaged spectrum, corrected for measured sea surface current, ranges between 0 and ≈1 m/s for incidence angles increasing from 0 to 70∘ . Besides the known wind-to-radar azimuth dependence, the DC can also depend on wind-to-dominant wave direction. For co-aligned wind and waves, a negative crosswind DC residual is found, ≈−0.1 m/s, at ≈20 ∘ incidence angle, becoming negligible at ≈ 60 ∘ , and raising to, ≈+0.5 m/s, at 70∘ . For our observations, with a rather constant dominant wave length, the DC is almost wind independent. Yet, results confirm that, besides surface currents, the DC encodes an expected wave-induced contribution. To help the interpretation, a two-scale model (KaDOP) is proposed to fit the observed DC, based on the radar modulation transfer function (MTF) previously developed for the same data set. Assuming universal spectral shape of energy containing sea surface waves, the wave-induced DC contribution is then expressed as a function of MTF, significant wave height, and wave peak frequency. The resulting KaDOP agrees well with independent DC data, except for swell-dominated cases. The swell impact is estimated using the KaDOP with a modified empirical MTF
Tipo:  Text
Idioma:  Inglês

Editor:  MDPI AG
Formato:  application/pdf
Fonte:  Remote Sensing (2072-4292) (MDPI AG), 2019-04 , Vol. 11 , N. 7 , P. 839 (24p.)
Direitos:  info:eu-repo/semantics/openAccess

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