Observations of the Earth using the SAR (Synthetic Aperture
Radar) of the ERS
On the oceans:
Most of the man-made illegal or accidental spills are well visible on radar images. Ships can be detected and tracked from their wakes. Also natural seepage from oil deposits can be observed. They provide hints to the oil industries. Scientists are studying the radar backscatter from the ocean surface related to wind and current fronts, to eddies, and to internal waves. In shallow waters SAR imagery allows to infer the bottom topography. The topography of the ocean floor can be mapped using the very precise - ERS Altimeter, because the sea bottom relief is reflected on the surface by small variations of the sea surface height.
The ocean waves and their direction of displacement can be derived from the ERS SAR sensor operated in "Wave Mode". This provides input for wave forecasting and for marine climatology.
At high latitudes, SAR data is very useful for regional ice monitoring. Information such as ice type and ice concentration can be derived and open leads detected. This is essential for navigation in ice-infested waters.
On the land:
The ability of SAR to penetrate cloud cover makes it particularly valuable in frequently cloudy areas such as the tropics. Image data serve to map and monitor the use of the land, and are of gaining importance for forestry and agriculture.
Geological or geomorphological features are enhanced in radar images thanks to the oblique viewing of the sensor and to its ability to penetrate - to a certain extent - the vegetation cover.
SAR data can be used to georefer other satellite imagery to high precision, and to update thematic maps more frequently and cost-effective, due to its availability independent from weather conditions.
In the aftermath of a flood, the ability of SAR to penetrate clouds is extremely useful. Here SAR data can help to optimize response initiatives and to assess damages.