Efficient Differential Reflectivity Processing Using Logarithmic Receivers

Abstract

The differential reflectivity (ZDR) measurement introduced by Seliga and Bringi has shown potential for extending cloud microphysical studies and improving rainfall rate measurement. The sensitivity of ZDR measurement requires it to be estimated with a high degree of accuracy. Our theoretical analysis and experimental observations show that the estimates of ZDR using log ratio estimators typically have twice the standard error compared to those from square law estimators. A ?lookup table technique? which converts the log value to the equivalent square law value prior to integration is proposed to improve the accuracy of ZDR estimates from logarithmic receivers. The size of the lookup table dictates the accuracy of the resulting ZDR estimate. Experimental observations demonstrate that the log receiver lookup table technique estimates ZDR to an accuracy nearly the same as that from a square law receiver. We present the implementation of this technique in integer arithmetic applied to the NCAR CP-2 radar.