Single Radar Specific Attenuation Precipitation Estimate Comparisons with MRMS Q3 and Dual Pol QPE

Abstract: As part of an effort to more explicitly use Dual Polarization (Dual Pol) information into the Multiple Radar-Multiple Sensor (MRMS) system, radar estimates developed from specific attenuation fields were compared with MRMS Quantitative Precipitation Estimates (QPE) radar only (Q3) and Dual Polarization estimates for six cases during the 2014 warm season. Performance was assessed via the comparison of precipitation estimates to Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) twenty-four hour accumulation gauge data while hourly automated gauge data (with quality controlled measures applied) were used for spatial and time series analysis. Rain estimates developed from specific attenuation show some encouraging results, in particular in reducing biases caused by evaporation of rain drops due to dry boundary layers or in situations where heavy, tropical like rainfall occurs. However, the data clearly shows an increased amount of variability mainly in lighter rainfall, where hail is present and in regions where the radar beam is likely intersecting the melting layer. The ongoing challenge of developing a real-time, automated method for identifying the situations where specific attenuation estimates will not be robust is discussed.