SUMMARYReflection coefficients measured over a wide variety of natural and agricultural vegetation surfaces in Nigeria (lat. 4 ' 40' to 13" 30") were between 0.05, to 0.25,; and were inversely related to the vegetation height. Considerable seasonal differences were found with unexpected low values of reflectivity during the harmattan haze in the dry season. Possible reasons for these seasonal differences are discussed. The weighted mean annual reflection coefficient for Nigeria was calculated to be 0.178. This value was consistent with the relationship between surface reflection coefficient and latitude found from similar results from six other locations in the Northern Hemisphere. Urban coefficients were found to be lower than those for rural settlements or temperate zone urban centres.
Drought prediction has been an age-old problem, but in more recent times the magnitude of the Sahelian drought has brought into focus the need to improve the techniques for predicting such droughts with some measure of accuracy. From the present state of knowledge, drought prediction is difficult, if not impossible. Two major approaches appear to be prominent in the search for appropriate techniques. These include the use of teleconnections and the development of numerical models.Essentially, time-lagged teleconnections rely on the assumption that changes induced in any one area of the world may produce changes elsewhere on a world-wide scale~ though tinle-lagged. The 1972-73 E1 Nifio off the west coast of South America is a good case in point. The development of numerical models which allow the incorporation of not only climatic factors but also man's impact on the natural environment, offers some ray of hope that the general circulation models (GCMs) may help to improve the techniques of drought prediction.
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