Discrimination of Africa´s vegetation using reconstructed ERS-1 imagery

Because of persistent cloud cover typical of equatorial regions, active microwave imagery such as ERS-1 SAR is preferred over high-resolution visible and near infrared spaceborne sensors. However, no active microwave instrument designed to provide continental coverage at resolutions similar to the popular AVHRR has ever flown. Satellite scatterometers are calibrated active microwave radar instruments originally designed to measure the radar backscatter of the ocean´s surface under all-weather conditions. The European Space Agency successfully launched its ERS-1 satellite into a quasi-polar mission-adjustable orbit in the summer of 1991. The instrument payload included the Active Microwave Instrument (AMI) which is capable of operating in a wind scatterometer mode (5.3 GHz) for the production of wind vector products. However, an image reconstruction technique developed by D.G. Long et al. (1993) has improved the AMI scatterometer resolution to 14 km (from 50 km), making it a candidate for coarse monitoring of cloudy global areas such as the Arctic, Antarctic, and continental equatorial forests. The goal of the research reported in this paper is to evaluate reconstructed ERS-1 scatterometry for discriminating between vegetation classes of continental Africa