Measurement and Characterization of Entropy and Degree of Polarization of Weather Radar Targets

Abstract

To date, few polarimetric weather radars have exhibited the capability to measure full scattering matrices. In contrast, in the SAR community, considerable experience has been gained in dealing with complete scattering matrices and their statistical behavior. This work aims to place weather radar parameters in a wider context in order to exploit more general concepts like target decomposition theorems and polarization basis transformations. Entropy, a fully polarimetric variable derived from the Cloude-Pottier decomposition, and the degree of polarization, derived from Wolf’s coherency matrix, are the subject of the present study. The theoretical analysis carried out in the first part of the paper is checked against fully polarimetric data from POLDIRAD, DLR research weather radar. Entropy and degree of polarization are compared with the copolar correlation coefficient in order to understand whether they can add value to radar meteorological investigations. Since the degree of polarization is available to conventional dual-polarization coherent systems, it is important to assess its potential for operational use.