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Mixture of ASAR and MERIS images of Namibia (Namibia_asar325_meris_PC123)

The image processing software LEOWorks was used to combine the two data sets. This is not a trivial job, but with some training you may be able to do it. Technical details and data are found at the end of this section.
 
 

	ASAR image of Namibian, 12 November 2003

A little bit of African geology

The result of this data merge is a strangely coloured but meaningful image. You can observe that the top right corner is all in blue. If you compare this image with image 'Namibia_meris_031215', you will find that the top right corner is all white, meaning that it is covered in clouds.
 
 

MERIS image of Namibia, 15 December 2003

On the contrary, the ASAR radar images the Earth's surface even in overcast weather. Consequently, for such areas we only have information from this sensor. This information is given in blue. We can recognise the coastline, a river delta of gravel and sand in white, and rocky mountains in blue. Elsewhere in the image the contribution of the colours of the MERIS image are added. They reveal different types of rock, or more precisely, the different minerals in the rock.

However, the contribution of blue tells us that the observed rock has a more or less weathered or cut surface (and is not as smooth as a sand plain). In fact, sand and all geologically young sediments appear in green.

In the coastal plain to the west (left), we can observe a beautiful field of giant dunes. All other geological formations are part of the Precambrian continental shield. The reddish colour indicates very old magmatic rocks such as granite; they are heavily fractured by faults (central and left part of the image). The red-bluish part in the centre of the image are rocks of volcanic origin. The yellowish brown areas central right are mainly very old sedimentary rocks. The yellow area at the bottom of the image also consists of sediments, and shows an impressive large fold.
 
 
Desert and scarce vegetation

There is very little vegetation in this area at the fringe of the Kalahari Desert. The climate allows only the growth of thorn trees and seasonal grass. Along the coast, the vegetation type is similar to the Sahara: it is a shrub desert. Towards the east, we encounter the little more humid escarpment with open evergreen savanna.

Around Windhoek, and elsewhere on the plateau, the typical vegetation is the open deciduous thorn-tree woodland. Windhoek is also the only large city in the image. It is represented by a small, bluish zone at the southern end of the long and well-marked mountain ridge near the central right edge of the image. If the image is displayed you can find Windhoek by means of its image coordinates: 742,414.

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