Spectral polarimetric approach to remote sensing of natural objects and environments

Coherent polarimetric radar facilities for remote sensing causes a rapid increase in the number of parameters measured. Study of relationships between Doppler and polarimetric parameters and development of new measurable variables that are characteristic and suitable for coherent polarimetry were made in recent works where spectral differential reflectivity and other Doppler-polarimetric parameters were introduced and investigated. Using spectral analysis, the polarization parameters can be expressed as functions of Doppler frequency, or more exactly, a radial velocity. Such Doppler-polarimetric approach to remote sensing can provide information about the velocity and shape of scatterers in the resolution volume of a meteorological object. This approach has been successfully used for remote sensing of rain and some other applications. In this paper we attempt to generalize this approach to a much wider class of problems in remote sensing of natural phenomena and objects. It is shown that frequency as the argument of a spectrum may reflect not only the Doppler frequency but also very different physical properties of the objects, depending on the characteristics of a particular task of remote sensing. Such generalization suggests a new spectral-polarization approach or method, which is useful for the study of distant objects and natural phenomena.