Satellite Eye for Galathea 3

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 Africa.

Technical information

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 from: http://galathea.oersted.dtu.dk/google/kmz/images/Vejr/Afrika/

The same pictures in jpg- and in geotif-format to analysis in the picture processing program can be downloaded from: http://galathea.oersted.dtu.dk/base/areas/Africa/

This week’s picture is delivered by Ørsted, DTU, which is a part of the project Satellite Eye for Galathea 3.