Assessing the role of dual-polarimetric radar in quantitative precipitation estimation and nowcasting in the Colorado Front Range region

Precipitation estimation from radar in complex terrain is subject to several sources of error including sparse radar coverage, terrain blockage and rapidly changing melting layer elevations. Errors in radar-derived quantitative precipitation estimates subsequently limit the skill of precipitation nowcasts and flash flood predictions from hydrological models. Dual-polarization radars will provide some improvement in the retrieval of cloud and precipitation characteristics including hydrometeor type and precipitation rate estimations. In this project we evaluate the performance of the CSU-CHILL radar against the operational NEXRAD radar network in its ability to better differentiate between liquid and ice phase hydrometeors and radar-derived QPEs for several different kinds of precipitation events, including a flash flood producing event. The two radar systems will be evaluated against several different ground-based precipitation measurement methodologies including weighing-type and tipping bucket rain gauges, vertically-pointing k-band radars and laser disdrometers. The novel aspect to be addressed by this study is that emphasis will be placed on analyzing terrain-dependent variations in precipitation characteristics as estimated by the NEXRAD and CHILL systems using novel ground measurements, distributed across a range of elevations in the Colorado Front Range. We conclude the presentation with a brief discussion on how the use of polarimetric-retrievals influence the performance of a storm-object based, extrapolation nowcast model.