multitemporal ERS-1 SAR scene represents about 100 by 100km and is composed
Red: 25 May 1992
Green: 16 Nov 1992
Blue: 20 April 1992
The scene shows the Black Sea to the north, the Bosporus separating Europe and
Asia and the Marmara Sea to the south. Well imaged in white are the heavily
populated area of Istanbul and Üksüdar at the southern end of the
Bosporus. Also visible are the two bridges connecting both parts of Turkey.
Just south of Istanbul many coloured points in the sea can be recognised. These
are ships awaiting the passage or harbour entrance. The red points are the ships
at anchor on the 25 May 1992, the green the one on 16 November 1992, etc. The
colours of the sea merely reflect the wind situation on the day of acquisition.
The prevailing magenta colour would mean that the 25 May but especially 20 April
were rather windy days.
SAR allows to discriminate well the type of land use: The grey area consists
of woods, mainly pine tree while the cyan colour can be attributed to any type
of agricultural and pasture land. However there is the light-bluish coastal
part of the Black Sea, mainly west of the Bosporus. It is an area of open-cast
mining of brown coal.
The reason of the good discrimination of wooded and non-wooded areas is explained
by soil moisture. The April and November acquisitions were done after rainfalls,
augmenting backscatter of the soil and decideous plants, but much less effecting
backscatter of coniferous.
(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,