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This paper provides some results of a comparison between several methods of AVHRR-HRPT 10-day and monthly compositing over an area of Western Africa between 4 N and 20 N, to provide syntheses of vegetation indices, temperature and albedo for time series analysis and mapping of physiographic units.
For vegetation indices and temperatures the direct maximization technique gives more spatially homogeneous results than indirect compositing techniques based on the maximisation of an other channel.
The GEMI vegetation index offers an advantage over NDVI as long as regions with highly reflective soils are discarted.
In arid zones surface temperature computed over cloud sides can be higher than over ground, which disturbs the maximization process and enlightens the precision limits of this measurement, which therefore is not automatically better than the maximization of the reflection temperature.
The albedo derived either from maximized NDVI or from surface temperature maximization provides the least precise results and therefore of little use in this state. te.

Additional information

Authors: BARTHOLOME E, Institut des Applications Spatiales, Ispra (IT)
Bibliographic Reference: Paper presented: 9e Conférence de l'Association Québécoise de Télédetection, Duchesnay (CA), April 30 - May 3, 1996
Availability: Available from (1) as Paper FR 39738 ORA
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