ESA - Observing the Earth - The power of two: Envisat demonstrates combined imagery from dual sensors

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The power of two: Envisat demonstrates combined imagery from dual sensors

31 October 2002

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ASAR and MERIS images of Corsica, Sardinia and the Italian coast, 26 June 2002

Credits: ESA

ASAR/MERIS data correlates for enhanced analyses

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Matching images of the islands of Corsica and Sardinia, with the Italian coast in the upper right-hand corner, acquired 26 June 2002 using Enivsat's Advanced Synthetic Aperture Radar (ASAR) to capture the image on the left, and the MEdium Resolution Imaging Spectrometer (MERIS) for the one on the right.

Credits: ESA

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The simultaneous observation of Corsica and Sardinia by ASAR and MERIS demonstrates the potential of combining the data from the two very different instruments for understanding complex Earth processes.
The images were acquired over a small low-pressure front between Corsica and the Italian peninsula. The centre of the depression shows up as a dark area in the ASAR image due to the low wind speeds at the system’s centre and the corresponding reduction in sea surface roughness. This is confirmed by the MERIS image that shows the depression’s cloud pattern.
There is a remarkable correlation between the cloud patterns observed by MERIS and that observed in the ASAR image. Between southern Corsica and the depression centre, a distinct change in surface wind speed can be determined on the ASAR image due to the sudden variation in tone. This is the surface impact of an atmospheric front, which can be easily seen in the MERIS image.
The area covers several major shipping lanes including the main route to Genoa as well as access to a major oil refinery near Cagliari in the south of Sardinia (where several ships can be seen as bright white points in the bay). The long, thin dark structures seen are slicks from illegally dumped oil. The presence of oil or natural films damps out the surface waves and reduces the observed backscatter levels.

Technical Information:
Instruments: MEdium Resolution Imaging Spectrometer (MERIS)
Advanced Synthetic Aperture Radar (ASAR)
Date of Acquisition: 26 June 2002
Orbit number: 01679
MERIS Instrument features: Reduced Resolution image (1200-meter resolution)
Radar Mode: WS
Orbit Direction: Descending
Radar Polarisation: VV

Credits: ESA

The first top-down/bottom-up space view of a hurricane

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ASAR and MERIS images of Hurricane Isidore off the Gulf of Mexico, acquired by Envisat 21 September 2002.

Credits: ESA

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This image shows the recent hurricane Isidore passing over the Gulf of Mexico. And demonstrates how features related to all of the principal dynamics can be observed.
The MERIS image shows a classic hurricane circulation pattern, with the cloud structure around the hurricane centre as warm moist air is entrained into the system. The eye can be clearly identified together with the thick cloud structures associated with the convection within the eye wall. The higher altitude outflow can be seen extending over Cuba as systems of thunderstorms.

Technical Information: Instruments: MEdium Resolution Imaging Spectrometer (MERIS)
Advanced Synthetic Aperture Radar (ASAR)
Date of Acquisition: 21 September 2002
Orbit number: 02928
MERIS Instrument features: Reduced Resolution image (1200-meter resolution)

Credits: ESA

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