Identifying ZDR Columns in Radar Data with the Hotspot Technique

Abstract

Abstract A novel differential reflectivity (ZDR) column detection method, the hotspot technique, has been developed. Utilizing constant altitude plan projection indicators (CAPPI) of ZDR, reflectivity, and a proxy for circular depolarization ratio at the height of the −10°C isotherm, the method identifies the location of the base of the ZDR column rather than the entire ZDR column depth. The new method is compared to two other existing ZDR column detection methods and shown to be an improvement in regions where there is a ZDR bias. Significance Statement Thunderstorm updrafts are the area of a storm where precipitation grows, electrification is initiated, and tornadoes may form. Therefore, accurate detection and quantification of updraft properties using weather radar data is of great importance for assessing a storm’s damage potential in real time. Current methods to automatically detect updraft areas, however, are error-prone due to common deficiencies in radar measurements. We present a novel algorithmic approach to identify storm updrafts that eliminates some of the known shortcomings of existing methods. In the future, our method could be used to develop new hail detection algorithms, or to improve short-term weather forecasting models.