Status of Dual Pol QPE in the WSR-88D Network

A new Quantitative Precipitation Estimation (QPE) algorithm is being fielded with the dual polarization upgrade to the nation-wide fleet of Weather Surveillance Radars-1988D (WSR-88Ds). The QPE performance has been examined for over 60 radar cases from across the contiguous United States for a wide variety of precipitation types. Preliminary results indicate that dual polarization QPE is generally an improvement over legacy estimates. On a subset of cases that have undergone detailed statistical analysis, the QPE algorithm reduces the bias error magnitude and RMSE over the WSR-88D's legacy Precipitation Processing System (PPS) algorithms; both reductions are statistically significant at p = 0.05. The nature of these improvements appears to depend on whether the beam is above the melting layer or below it. The height of the melting layer is provided by the melting layer algorithm which also affects the hydrometeor classification algorithm. The QPE requires accurate information from both algorithms. Dense, high-quality rain gauge networks are needed to provide robust statistical analyses of radar-based precipitation algorithms such as the QPE. Field offices are being encouraged to use a new web-based QPE diagnostic tool for dual polarization performance in their areas. This paper provides an update on the QPE dual polarization rainfall estimation, challenges in the analysis of QPE, training efforts, and a discussion of future work.