ERS-1 SAR scene represents about 100 by 100 km was acquired by Fucino/Italy
on orbit 1094, 1 October 1991 at 10:25 hours UTC and processed by ESA/ESRIN.
The image centre is located at 25-48 north and
This area in the south of Algeria is one of the most remote and desolate areas
of the Sahara, very dry and even the few springs are brackish due to the high
The SAR image shows a beautiful outcrop pattern of concentric loops and ellipses.
It is the result of erosion by wind of a slightly deformed Paleozoic sedimentary
rock, not unlike as the grain of wood appears after sandpapering. Since virtually
no rain is provided to this area the rock is weathering in situ. It is the surface
roughness that SAR imagery can reveal. The rougher or stonier a surface the
brighter it appears in the image. Hence darker bands belong to softer rock with
small stones or with a sandy surface.
Topography is of minor importance in the region, but still even very low cliffs
and faults are brightly imaged. Together with visible/infrared multispectral
satellite data a detailed geological analysis can be performed.
(ERS Data Utilization Section, ESA/ESRIN)
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,