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