Africa seen from Envisat, September 21-25 2006.
Envisat, ESA’S environmental satellite, is floating in a
polar orbit around the earth. The instrument MERIS observes the
earth by means of scanning in 15 bands of the electromagnetic
spectrum. Here you see a combination of bands which include the
near infra-red light that is invisible to the human eye. As
green plants do not use the near infra-red light in the
photosynthesis, the reflection from this light is big from green
vegetation. If you assign the infrared band to the red, the red
band to and the green band to blue, you get a so-called
false-colour image of the surface of the earth where the
vegetation is shown in various red colours.
In the picture you can see the rain forest in central Africa
in bright red colours together with the transition from the
savanna to the Sahara, the so-called Sahel area. Furthermore the
intertropical convergence zone, ITC, with the many clouds can be
seen. Here at equinox it is a little north of the Equator on its
way south. ITC brings precipitation to the central part of
Mosaic produced in Google Earth from MERIS data from Envisat.
The solution has been reduced to 2 km x 2km per pixel.
You can make the mosaic in Google Earth yourself. The single
images which come from the Envisat orbits, can be downloaded
The same pictures in jpg- and in geotif-format to analysis in
the picture processing program can be downloaded from:
This week’s picture is delivered by Ørsted, DTU, which is a
part of the project Satellite Eye for Galathea 3.