WDT's Polarimetric Radar Identification System (POLARIS): Using the Hydrometeor Classification Algorithm for hail detection and size discrimination

Weather Decision Technologies Inc. (WDT) specializes in transferring state-of-the-science meteorological algorithms and data from research to operations. An example of this is WDT's development of POLARIS (Polarimetric Radar Identification System) that ingests and analyzes dual-polarization radar data from all WSR-88D radars across the CONUS. Now that the Dual-Pol deployment has been completed across the CONUS, continued research and development efforts have focused on mitigating data issues seen throughout the WSR-88D network while also producing unique, enhanced products for clients.

POLARIS was developed based on the Hydrometeor Classification Algorithm (HCA) of the National Severe Storms Laboratory. WDT has since added new capabilities and is currently engaged in research on the detection and size discrimination of hail. Current research has focused on the discrimination of hail into 3 size categories: small (less than 2.5 cm diameter), large (more than 2.5 cm but less than 5 cm diameter) and giant (greater than 5 cm diameter). Many commercial enterprises require accurate spatial depictions of hail storms and more granularity in these standard Dual-Pol hail size categories, especially in the giant regime.

Using high-resolution ground truth data in conjunction with the Dual-Pol radar data, WDT has attempted to further refine the HCA to include more specific hail size categories. Preliminary results suggest that Dual-Pol detections of hail provide a more accurate depiction of the area of hail fall compared with reflectivity only estimates. Also, the standard 3 category hail identifications provide reliable thresholds upon which hail size data from the legacy hail detection algorithm can be constrained.