POLARIZATION OF THE SOLAR LIGHT SCATTERED BY THE EARTH ATMOSPHERE SYSTEM AS OBSERVED FROM THE UNITED-STATES-SHUTTLE

During the four American space Shuttle missions of year 1985, the crew members took pictures of the Earth in polarized light. This data set is a unique experiment involving extensive measurements in polarizatio n. The results that have been already reported in the literature illus trate different potential applications on a qualitative basis. We exam ine here the possibilities of achieving quantitative analysis of the i mages. The first step was to validate the experiment. Different proble ms have been encountered: calibration, uncertainties on the direction of polarization, induced polarization by the Shuttle window, and nonli nearity of the film response. The second part of the article is devote d to the analysis of a set of selected images. The consistency of the calibration is proven for snow or sand observations for which ground m easurements, reported in the literature, can be used for comparison wi th respect to the spatial homogeneity of the target. The potential of polarization for agriculture inventory use is then illustrated by rela ting space observations to existing ground measurement. Finally, durin g an atmospheric contamination event, the analysis of the polarization allows us to characterize the origin of the pollution as forest fire smoke.