A Statistical Comparison of the Accuracy of Precipitation Estimation Using Dual-Polarization and Single-Polarization Radar

Widespread use of radar for meteorological purposes began after the conclusion of World War II. Since this time, a focus of research has been improvement of the precipitation estimates generated by radar. Currently research is being conducted to determine if dual-polarization radar improves precipitation estimates when compared to single-polarization radar. This study statistically compared precipitation estimates in the state of Iowa from dual-pol and single-pol Next Generation Weather Radar (NEXRAD) using the statistical measures of Standard Error (SE), Pearson Correlation Coefficient (PCC), and Normalized Bias (NB). This research evaluated the 15-minute rainfall rate, 15-minute precipitation, and total precipitation using a reflectivity rainfall rate relationship for single-pol radar and a reflectivity and differential reflectivity rainfall rate relationship for dual-pol radar. The cases were additionally evaluated for the effect that the distance from the radar and the intensity played on the SE. This study was not able to provide statistically significant evidence that dual-pol radar is more accurate than single-pol radar for NEXRADs across the state of Iowa. Additionally, the single-pol radar was found to be more consistent in precipitation estimation accuracy. There was no distance bias found for either dual-pol or single-pol radar for all variables investigated in the study. Dual-pol radar estimates were more accurate than single-pol radar estimates for cases that consist exclusively of light rainfall