SATELLITE IMAGE RADIOMETRY: FROM PHOTONS TO CALIBRATED EARTH SCIENCE DATA

摘要

Today's remote sensing satellite systems yield digital images that provide unprecedented observations of the Earth from space that are both synoptic and detailed in nature. There is tremendous interest in the use of these images to derive information about current states of geophysical and biophysical variables and to monitor their changes. This article outlines the key steps needed to ensure that terrestrial variables retrieved from optical satellite sensor systems are calibrated to a common physical scale. The emphasis is placed on the multiple methodologies used post-launch to convert digital image data to calibrated products for the user community. For most spectral domains and targets of interest, the retrieval of land, atmosphere and ocean information from exo-atmos-pheric image data requires sensor radiometric calibration, correction for atmospheric scattering and absorption effects, and an understanding of target reflectance behaviour. The article focuses on reflectance, a land surface parameter of wide interest, as an example.