On the relationship between the degree of preferred orientation in precipitation and dual‐polarization radar echo characteristics

The relationship between preferred orientation of atmospheric precipitation particles and the radar echoes obtained with two-channel polarization diversity radar systems is considered. An experimental technique in which measurements are made sequentially at circular and linear polarization for the purpose of determining the degree of preferred orientation is described. This technique, which requires rotation of the direction of linear polarization during the observations, provides a means for separating the effects of preferred orientation from the effects of particle shape distributions. It is shown that two orientation parameters are required to describe the measurements made with the differing polarization base vectors. Representative experimental results on various types of precipitation are reported. The results show that both orientation effects and shape effects are significant in remote sensing of precipitation.