January 20, 2006
This ASAR APG image shows an area centered over the city of Bordeaux (yellow tone in the center of the image) within the Garonne valley. Bordeaux, a commercial seaport and industrial city, is located approximately 20 kilometers south of the confluence of the Garonne and Dordogne rivers. To the east, the city of Libourne, within Dordogne valley, is also seen in yellow tones. The widened watercourse of the two merged rivers, flowing westward toward the coast of France, is known as the Gironde. It is the largest estuary in France and one of the largest in Europe. One part of the estuary can be seen at the top center of the image, divided by small islands and mud banks. The image is a color composite where the red channel contains the VH polarized image, the green channel contains the VV polarized image and the blue channel contains the ratio between the amplitude in VV and VH. In the left part of the image, from top to bottom, Lake Hourtin, Lake Lacanau, a part of the Bassin d'Arcachon and the lake Cazaux are shown in turquoise color (high VV scattering). The high VV scattering over lakes and rivers (note that Garonne, Dordogne and Gironde rivers are also seen in blue tones) is due to the strong winds affecting the local water surface roughness the day this image was acquired. This image demonstrates the advantages of using cross polarized data to discriminate between vegetated areas with strong volume scattering, appearing in brown and orange tones in the image due to the high VH scattering and low-vegetated areas shown in blue tones in the image as a result of the low VH scattering. Both the peninsula between the two rivers and Gironde's banks are famous wine-producing regions (vineyards are shown in blue tones corresponding to low VH scattering). Instead, circular sweet corn fields are seen in blue tones to the east of the Bassin d'Arcachon. The Eyre River, covered by dense vegetation, is seen in the bottom left corner of the image in orange tones (high VH scattering). The Bay of Arcachon is highly subjected to the rhythm of the tides that cover and uncover its great sandbanks and its oyster-beds, seen in the image in dark blue tones (low VV scattering) while the main channels of the bay, in turquoise color, are always full of water. Civil infrastructures are clearly visible in the image such as Bordeaux airport, seen to the west of the city in dark blue color (low VH and VV scattering), bridges over Garonne and Dordogne rivers or man-made channels (turquoise color) to the northeast and southeast of the Bassin d'Arcachon. Principal highways are also seen in dark blue tones, for example surrounding the city of Bordeaux or from south of the Bay of Arcachon to Bordeaux.
- Satellite: Envisat
- Instrument: ASAR
- Acquisition: 13-Apr-2003
- Orbit nr: 05852
- Center coordinates: lat. 44.79, lon. -0.62
Topics: Aquitaine, Gironde, Departments of France, Dordogne river, Garonne river, Arcachon, Garonne, DORDOGNE, Eyre, Turquoise, Geography of France, Bordeaux wine, Bordeaux, Scattering