The impact of closely spaced elevation scans on observations obtained using the NWRT Phased Array Radar

A current research goal of the National Weather Radar Testbed (NWRT) program is to evaluate adaptive scanning methods for phased array radar (PAR). To develop such an algorithm, it is necessary to determine an optimized combination of radar settings for a particular weather event. For example, it is desirable for an adaptive scanning method to obtain complete information on a storm's vertical structure. A high number of closely spaced elevation scans may provide detailed observations for hailstorm and winter precipitation forecasts. However, a greater number of elevation scans will require a longer volume update rate, which could hinder the detection of rapidly evolving features. The purpose of this study is to test scanning strategies with a large number of closely spaced elevation scans, to determine whether additional vertical detail will provide improved observations over current scanning methods.

For the present study, two sets of scanning strategies have been developed for use on the NWRT PAR. One method has been used to sample rain/snow transition regions and vertical snow squall structure during two winter events over central Oklahoma. Results from this scanning method will be presented in comparison with those obtained using current WSR-88D scanning strategies. One focus of the analysis will be determining whether data from the PAR scans provides useful information on the vertical structure and evolution of snow, sleet and freezing rain. A second method is designed to provide highly detailed scans of hailstorms and will be tested during the Spring 2009 PAR Innovative Sensing Experiment (PARISE) at NOAA's Hazardous Weather Testbed in Norman, Oklahoma. Feedback will be gathered from PARISE participants to determine whether closely spaced elevation scans provide improved detail when compared to existing WSR-88D scanning strategies. The PAR hailstorm data will be examined alongside dual-polarimetric RHI scans obtained from the University of Oklahoma's new Polarimetric Radar for Innovations in Meteorology and Engineering (OU-PRIME). Analysis of the storm evolution depicted by the two radars will provide insights into future settings and improvements that may be applied to adaptive scanning methods.