MARSAIS Products
MARSAIS (Marine SAR Analysis and Interpretation System) gives you the following environmental products based on Earth Observation data:
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| © 1993 ESA |
Wind: Presence of rolls in the atmospheric boundary layer can cause streaks, i.e. patterns of parallel lines, to appear in SAR images, as shown here in an image over Lofoten in northern Norway. The wind direction is perpendicular to the streaks. Hence, wind streaks can be used to estimate the wind direction with an ambiguity of 180°. Using additional information the wind direction can be determined unambigously, and algorithms used to calculate the wind speed in the area. > read more
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| © 2003 ESA |
Waves: This Envisat ASAR image illustrates how satellite radar depicts wave patterns on the ocean surface. The refraction of waves around the Pointe du Grouin in the middle of the image is clearly visible. The dark areas in the image image correspond to regions of very weak winds. For ASAR data, a new algorithm can be used to estimate waves parameters such as height, direction and period. > read more
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| © 1996 ESA |
Currents: Surface current gradients become visible in SAR images via hydrodynamic modulation of the surface roughness (wave-current interaction). A model can retrieve quantitative information on current variations, e.g. the strength and width of oceanic fronts, from the strength and shape of their SAR signatures. > read more
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| © 1993 ESA |
Internal Waves: Surface current variations associated with oceanic internal waves become visible in SAR images via hydrodynamic modulation of the surface roughness (wave-current interaction) as dark and bright bands. An algorithm can retrieve quantitative information on the surface current variation and the interface properties (internal wave amplitude, depth, density change) from the strength and the inter-band distance of their SAR signatures using auxiliary input data. > read more
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| © 1994 DLR |
Oil Spills: Pollution of oil or oil-based material from ships or platforms can be seen as dark features (slicks) in SAR images. However, there are also a number of natural phenomena that can give rise to slick signatures, e.g. natural film and low wind areas. Therefore, additional information is often needed to determine the cause of a slick. For instance, the shape of the slick, the signatures of the surrounding area and meteorological conditions at and before image acquisition. The left side image shows a slick with a complex shape, which has been classified as an oil spill by an interactive algorithm. > read more
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| © 2000 NOAA | © 2000 ESA |
Synergy: Synergy between SAR images and data from other remote sensors can significantly improve the interpretation of SAR signatures. For instance, this example illustrates how the origin of SAR signatures of natural surface films (on the right) is explained by a coincident sea surface temperature image (on the left): a thermal front is located in the area showing surface films in the SAR image, so it is likely that the films are accumulated by a converging surface current at the front. > read more