Performance of the Enhanced Reflectivity Implementation in Operational Dual-polarization Radar Environments

Dual-polarization have unique characteristics in precipitation namely, the correlation between the signal returns from two polarization states is very high and their relative phase evolves slowly as function of range. Utilizing the covariance characteristics of precipitation, Keranen and Chandrasekar (2011) developed an “Enhanced reflectivity factor estimate” based on both polarization returns. This estimate was also shown very useful to improve the detection sensitivity of operational weather radars. Since then this high sensitivity reflectivity factor has been installed in several operational dual-polarization radar systems. This paper presents a detailed comparison of the performance of the new reflectivity estimate compared to the traditional estimates obtainable from both horizontal and vertically polarized returns, from several operational radar systems. Special attention is paid to low SNR regions from the perspective of early storm detection as well as inherently weak echo observations such as in snow events. Statistical analysis shows that the enhanced reflectivity covers larger snow coverage region, as well as detects precipitation development sooner. The operational impact such as how much sooner the enhanced reflectivity is seen compared to traditional reflectivity is also presented.

Keränen R. and Chandrasekar V., 2011: “Analysis of dual polarization radar observations in the Helsinki test bed” AMS, 35th Conference on Radar Meteorology, Pittsburg,PA, September 2011