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| Yurovskaya, Maria; Kudryavtsev, Vladimir; Chapron, Bertrand; Collard, Fabrice. |
| The Sentinel-2 MultiSpectral Instrument (MSI) collects multiple spectral band images, corresponding to specific sensing wavelengths and spatial resolutions, i.e. 10 m, 20 m and 60 m, respectively. Images are collected one at the time with a given time-lag between observations. Under favorable conditions, spatio-temporal characteristics of propagating ocean surface waves can thus uniquely be retrieved. A method for surface current vector field reconstruction is then developed. Demonstrated over different deep ocean regions, the retrieved surface current fields well compare with medium-resolution ocean circulation model or derived-velocities from altimeter measurements. At finer scales, the surface wave-conservation law is recovered, with the associated... |
| Tipo: Text |
Palavras-chave: Ocean currents; Sea surface optical images; Wave dispersion relation; Time lag; Wave breaking; Sentinel-2; Satellite methods. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00587/69865/67918.pdf |
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| Misra, Ankita; Chapron, Bertrand; Nouguier, Frederic; Ramakrishnan, Balaji; Yurovskaya, Maria. |
| Local changes in specular reflections of visible sunlight on the ocean surfaces can be captured effectively by satellite sensors operating in the visible range of the electromagnetic spectrum. This causes the sun-glint imagery to closely resemble the oceanic images obtained using Synthetic Aperture Radar (SAR) further allowing the identification of the various fine scale structures and patterns of the ocean. Moreover, at relevant spatial resolutions, cloud-free conditions as well as optimum relative positions of the sensor, sun and the wave front it is possible to image ocean waves, wave transformations and refraction patterns using Satellite Sun-glint imagery (SSGI). In the present study, Landsat OLI imagery captured along the coast of Brest, France is... |
| Tipo: Text |
Palavras-chave: Sun-glint Imagery; Wave transformation; Landsat 8 OLI; Fast Fourier Transform(FFT); Cross-spectral analysis. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00476/58787/61791.pdf |
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| Kudryavtsev, Vladimir; Yurovskaya, Maria; Chapron, Bertrand; Collard, Fabrice; Donlon, Craig. |
| Under favorable imaging conditions, the Sentinel-2 Multi-Spectral Instrument (MSI) can provide spectacular and novel quantitative ocean surface wave directional measurements in satellite Sun Glitter Imagery (SSGI). Owing to a relatively large-swath with high-spatial resolution (10 m), ocean surface roughness mapping capabilities, changes in ocean wave energy, and propagation direction can be precisely quantified at very high resolution, across spatial distances of 10 km and more. This provides unique opportunities to study ocean wave refraction induced by spatial varying surface currents. As expected and demonstrated over the Grand Agulhas current area, the mesoscale variability of near-surface currents, documented and reconstructed from satellite... |
| Tipo: Text |
Palavras-chave: Satellite Sun Glitter Imagery; Ocean surface waves; Waves transformation on the currents. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00381/49281/49677.pdf |
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| Ardhuin, Fabrice; Alday Gonzalez, Matias Felipe; Yurovskaya, Maria. |
| The Total Surface Current Velocity (TSCV) - the horizontal vector quantity that advects seawater - is an Essential Climate Variable, with few observations available today. The TSCV can be derived from the phase speed of surface gravity waves, and the estimates of the phase speeds of different wavelengths could give a measure of the vertical shear. Here we combine 10-m resolution Level-1C of the Sentinel 2 Multispectral Instrument, acquired with time lags up to 1s, and numerical simulation of these images. Retrieving the near surface shear requires a specific attention to waves in opposing direction when estimating a single phase speed from the phase difference in an image pair. Opposing waves lead to errors in phase speeds that are most frequent for... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00691/80283/83371.pdf |
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| Yurovskaya, Maria; Rascle, Nicolas; Kudryavtsev, Vladimir; Chapron, Bertrand; Marie, Louis; Molemaker, Jeroen. |
| Reconstruction and evolution of two-dimensional spectra of surface waves in the Gulf of Mexico are derived from airborne sun-glitter imagery. As the proposed method is based on a linear transfer function deduced from the shape of the sunglitter brightness, the absolute wavenumber elevation spectrum does not require any additional assumption or information about sky brightness, wind or wave energy. The detailed description of the airborne image processing method is given. As demonstrated, retrieved spectra agree well with nearby NDBC buoy data, both for spectrum shape, level and energy angular distribution. The 180-degree wave direction ambiguity, inherent to image-derived spectra, is eliminated by using cross-correlation analysis between two consecutive... |
| Tipo: Text |
Palavras-chave: Sunglitter; Sea surface waves; Directional wave spectrum; Aerial photography; Field measurements; Remote sensing observations; High resolution; Drone. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00465/57712/60174.pdf |
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