The public's serious concern about the uncertainties and dangers of the conse- quences of human activities on environmental quality demands policies to control the situation and to prevent its deterioration. But far-reaching decisions on the environmental policy are impaired or even made impossible as long as the relevant ecological relations are not sufficiently understood and large-scale quantitative information on the most important parameters is not available in sufficient quality and quantity. The techniques of remote sensing offer new ways of procuring data on natural phenomena with...