Rainfall Estimation Using Polarimetric Techniques at C-Band Frequencies

Gianfranco Scarchilli Istituto di Fisica dell' Atmosfera (CNR), Rome, Italy

Search for other papers by Gianfranco Scarchilli in
Current site
Google Scholar
PubMed
Close
,
Eugenio Goroucci Istituto di Fisica dell' Atmosfera (CNR), Rome, Italy

Search for other papers by Eugenio Goroucci in
Current site
Google Scholar
PubMed
Close
,
V. Chandrasekar Colorado State University, Fort Collins, Colorado

Search for other papers by V. Chandrasekar in
Current site
Google Scholar
PubMed
Close
, and
Thomas A. Seliga Electromagnetics and Remote Sensing Laboratory, Department of Electrical Engineering, University of Washington, Seattle, Washington

Search for other papers by Thomas A. Seliga in
Current site
Google Scholar
PubMed
Close
Full access

Abstract

The accuracy of radar measurements and their derived parameters, such as rainfall rate, are compromised by errors caused by propagation effects at C-band frequencies. The radar measurements of reflectivity factor Z and differential reflectivity ZDR are affected by the absolute and differential attenuation through the rain medium. Another useful radar-derived parameter, differential propagation phase shift ΦDP, is contaminated by the differential phase on backscatter δ, which attains significant values in rainfall at C-band frequencies. In this paper we present a technique to correct these propagation and backscatter effects by application of an algorithm that corrects first Z and ZDR, using relationships between the specific and differential attenuations versus phase shift, which is followed by estimation of the differential backscatter phase shift parameter δ from the corrected ZDR. Simulation results are presented to demonstrate the effectiveness of this correction procedure for two cases: (a) uniform rainfall along the path, and (b) rainfall varying with range. We also present estimates of accuracy in the measurement of radar-derived rainfall rates made after applying this correction procedure.

Abstract

The accuracy of radar measurements and their derived parameters, such as rainfall rate, are compromised by errors caused by propagation effects at C-band frequencies. The radar measurements of reflectivity factor Z and differential reflectivity ZDR are affected by the absolute and differential attenuation through the rain medium. Another useful radar-derived parameter, differential propagation phase shift ΦDP, is contaminated by the differential phase on backscatter δ, which attains significant values in rainfall at C-band frequencies. In this paper we present a technique to correct these propagation and backscatter effects by application of an algorithm that corrects first Z and ZDR, using relationships between the specific and differential attenuations versus phase shift, which is followed by estimation of the differential backscatter phase shift parameter δ from the corrected ZDR. Simulation results are presented to demonstrate the effectiveness of this correction procedure for two cases: (a) uniform rainfall along the path, and (b) rainfall varying with range. We also present estimates of accuracy in the measurement of radar-derived rainfall rates made after applying this correction procedure.

Save