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

Multiparameter radar measurements of rainfall, namely, reflectivity factor [Z.sub.H], differential reflectivity [Z.sub.DR], and specific differential phase [K.sub.DP] lie in a constrained three-dimensional (3-D) space and therefore measurement of [Z.sub.H], [Z.sub.DR], or [K.sub.DP], should be consistent with the other two. This self-consistency relationship between [Z.sub.H], [Z.sub.DR], and [K.sub.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. Index Terms - Multiparameter, polarimetry, precipitation, radar resolution.