Potential and limitations of information extraction on the terrestrial biosphere from satellite remote sensing

The extraction of information on terrestrial environments from satellite observations requires the use of quantitative models to interpret the radiation data collected in space. Several approaches are feasible, ranging from the development of models capable of explaining the nature of the measured physical signal or of characterizing the state of the system under observation, to the establishment of empirical correlations between the variables of interest and the remote measurements. The premises and implications of these approaches are discussed with special emphasis on the mathematical and numerical requirements. Findings are condensed in 10 formal propositions, in the hope of clarifying the nature and domain of applicability of remote sensing.