Oil slick off Sweden

This 100-km swath ERS-2 SAR image was taken on the evening of Monday 2 June, and shows the oil slick poised ominously close to Sweden's south coast, on the bottom right of the image.

Unlike a conventional visual picture, SAR images record the relative roughness of different surfaces. This makes them especially useful for charting oil spills – a capability well demonstrated during the much larger Galicia oil spill off Spain last autumn – because oil has a smoother surface than water, and so shows up blacker. On land it can also be seen how the SAR distinguishes between different vegetation types across Swedish farmland.  
 

Swedish soldiers prepare for an expected oil spill

Local authorities responded quickly to the threat, and six oil containment ships from Denmark, Sweden and Germany succeeded in skimming much of the oil up before it reached the coast. Hundreds of people helped clear up what oil did make it ashore.

The sunken freighter poses no threat to shipping – upwards of 160 000 craft use the Danish straits annually – but as well as its cargo of 66 000 tons of fertiliser, the ship retains another 1600 tons of oil aboard which might still leak out.

ESA plans to carry out follow up imaging of the area starting next Wednesday 11 June, using Envisat's ASAR instrument as well as ERS-2. These images will be placed at the disposal of civil protection authorities if needed.

For more information on the current and upcoming activities of ESA's Earth Observation satellites, go to http://earth.esa.int/ew/planning