Hail storm hazard in urban areas: identification and probability of occurrence by using a single-polarization X-band weather radar

Abstract

Abstract. This work exploits the potentiality of hail warning, based on single-polarization X-band weather radar measurements and tested on a large and well-documented data set of thunderstorm events in southern Italy near Naples. Even though X-band radars may suffer of two-way path attenuation especially at long ranges, due to their relatively low cost their use is rapidly 10 increasing for short-range applications such as urban environments. To identify hail through radar measurements, two different methodologies have been selected and adapted to X-band data within the study area: one uses the Waldvogel (WAL) approach, whereas the other one uses the Vertically-Integrated Liquid Density (VIL-Density) product. The study aims at developing a Probability-of-Hail (POH) index in order to support hail risk management at urban scales. In order to find the optimal threshold values to discriminate between hail and severe rain, an extensive intercomparison between outcomes of the two methodologies 15 and ground truth observations of hail has been performed, using a 2x2 contingency table and statistical scores.The results show that both methods are accurate for hail detection in the area of interest, although VIL-Density product is less satisfactory than WAL method in terms of false alarm ratio. The relationship between the output of these two methodologies and POH has been derived through a heuristic approach, using a third-order polynomial fitting curve. As an example, the POH indexes have been applied for the thunderstorm event occurred on 21 July 2014, proving to be reliable for hail core detection. 20

10th European Conference on Radar in Meteorology and Hydrology (ERAD 2018) : 1-6 July 2018, Ede-Wageningen, The Netherlands

“…Several algorithms exist for the detection of hail using single polarization weather radars, and some studies have been made for their comparison and their skill characterization (Holleman , 2001) also focusing on X-band systems (Capozzi, Picciotti, Mazzarella, Budillon, & Marzano, 2016).…”

“…Given the VILD in g m -3 , the probability of hail occurrence is defined as a cubic function. In this work we will adopt the coefficient derived in (Capozzi, Picciotti, Mazzarella, Budillon, & Marzano, 2016), resulting from the analysis of VILD measured for about fifty strong storms in the Gulf of Naples from 2012 to 2015:…”

Multi-Variable Classification Approach for the Detection of Lightning Activity Using a Low-Cost and Portable X Band Radar

“…The latter, as demonstrated in [43,44], may exhibit acceptable performance at short ranges (i.e., below 80 km) when compared to conventional systems (the S and C-band systems), but with the advantage of more affordable costs in terms of infrastructure, power requirements and maintenance. In this respect, our work fits a research path that in recent years has been devoted to exploit the potential usefulness of low-cost X-band radars in weather surveillance, especially at urban scale (e.g., [43,[45][46][47][48]); 3.…”