Correcting C-band radar reflectivity and differential reflectivity data for rain attenuation: a self-consistent method with constraints

Abstract

Quantitative use of C-band radar measurements of reflectivity (Z/sub h/) and differential reflectivity (Z/sub dr/) demands the use of accurate attenuation-correction procedures, especially in convective rain events. With the availability of differential phase measurements (/spl Phi//sub dp/) with a dual-polarized radar, it is now possible to improve and stabilize attenuation-correction schemes over earlier schemes which did not use /spl Phi//sub dp/. The recent introduction of constraint-based correction schemes using /spl Phi//sub dp/ constitute an important advance. In this paper, a self-consistent, constraint-based algorithm is proposed and evaluated which extends the previous approaches in several important respects. Radar data collected by the C-POL radar during the South China Sea Monsoon Experiment (SCSMEX) are used to illustrate the correction scheme. The corrected radar data are then compared against disdrometer-based scattering simulations, the disdrometer data being acquired during SCSMEX. A new algorithm is used to retrieve the median volume diameter from the corrected Z/sub h/, corrected Z/sub dr/, and K/sub dp/ radar measurements which is relatively immune to the precise drop axis ratio versus drop diameter relation. Histograms of the radar-retrieved D/sub 0/ compared against D/sub 0/ from disdrometer data are in remarkable good agreement lending further validity to the proposed attenuation-correction scheme, as well as to confidence in the use of C-band radar for the remote measurement of rain microphysics.