THE MULTISPECTRAL COLOR-COMPOSITE TECHNIQUE AN IMPROVED METHOD TO DISPLAY METEOROLOGICAL SATELLITE IMAGERY

The Multispectral Colour-Composite technique consists in superimposing three eight-bit images, each one resulting from a combination of channels and having a different colour (blue, green or red). It has been widely used for many years with Landsat data. The result is a coloured image where each surface type (i.e. the different clouds, the oceans, the continents, the snow) is characterized by its colour, its intensity and its texture. This technique enables a fast use of all the available channels, and avoids the visual analysis of two black and white images. The distinction, with METEOSAT or GOES imagery, between low, medium, high and thin clouds during the day is much easier with this method. This technique applied to NOAA-9 or NOAA-11 AVHRR data enables an easy detection to be made of stratus during night-time and the detection of ground covered by snow during daytime. This technique is routinely applied to daytime and night-time AVHRR imagery received in the Centre de Meteorologic Spatiale in Lannion to produce quick-looks available on slides. Midday METEOSAT full disc processed by this technique is daily sent to the French television channel TV1.