Detection and estimation of reflectivity gradients in the radar resolution volume using multiparameter radar measurements

Multiparameter radar measurements of rainfall, namely, reflectivity factor Z_H, differential reflectivity Z_DR , and specific differential phase K_DP lie in a constrained three-dimensional (3D) space and therefore measurement of Z _H, Z_DR, or, K_DP should be consistent with the other two. This self-consistency relationship between Z_H , Z_DR, and K_DP is valid when the radar resolution volume is homogeneous. When there are reflectivity gradients within the radar resolution cell, the self-consistency relation is perturbed. This perturbation can be utilized to detect the presence of gradients in the radar resolution volume. This paper presents a technique to detect and estimate reflectivity gradients in the resolution cell. The technique is evaluated using theoretical analysis as well as experimental data collected by the NCAR CP-2 radar. It is demonstrated that the presence of reflectivity gradients larger than a few decibels can be detected using the algorithm developed in this paper