Paper
19 September 2016 Surface wind speed estimation over open ocean using bidirectional observation by Sentinel-2/MSI and Landsat-8/OLI
Bertrand Fougnie, Olivier Hagolle, Sophie Lachérade
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Abstract
Large stripes, observed on first Sentinel-2/MSI images over ocean, are not due to instrumental artifacts but to the target itself. The same kind of signature can be observed on Landsat-8/OLI. Both MSI and OLI instruments are known for their excellent radiometric quality for land observation. The MSI’s focal plane is composed by 12 elements to cover the 300km-swath, respectively 14 elements for a 185km-swath for OLI. For technical reason, elements were slightly shifted forward/backward alternatively in the focal plane. As a consequence, each element has a different viewing angle than the next/previous one, leading for a considered target on the ground to a significant difference in zenith/azimuthal viewing angles. These angular variations, fully acceptable for the land mission, become sensitive for specific targets such as sunglint, a highly directional signal. It was already demonstrated the possibility to retrieve surface wind speed from bidirectional space measurements with POLDER/PARASOL instruments. Indeed, using multiple viewing angles is a good way to better constrain the inversion because it doesn’t fully rely on the absolute estimation of a unique measurement. Somehow, MSI or OLI can be seen as bidirectional sensors for targets located between 2 elements of the focal plane. Knowing the exact acquisition geometry, the observed radiometric gap can be directly related to the surface wind speed. Because it is a relative estimation, this inversion becomes more robust to aerosol contamination. Finally, an improved retrieval can be foreseen thanks to the multiple spectral bands provided by MSI and OLI.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bertrand Fougnie, Olivier Hagolle, and Sophie Lachérade "Surface wind speed estimation over open ocean using bidirectional observation by Sentinel-2/MSI and Landsat-8/OLI", Proc. SPIE 9972, Earth Observing Systems XXI, 997211 (19 September 2016); https://doi.org/10.1117/12.2237597
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KEYWORDS
Multispectral imaging

Reflectivity

Earth observing sensors

Landsat

Sensors

Aerosols

Satellites

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