Investigation on radar characteristics of hailstorms seeded with the glaciogenic reagent in Romania

Abstract

An operational hail suppression program has been based in Romania since 2005. The program is designed to reduce hail damage in the most vulnerable agricultural areas (protected areas) of the country. An exploratory analysis of volume-scan, S-band and C-band radars data, using a storm cell tracking software, was conducted to calculate six radar-derived parameters associated with hail from 51 seeded storms during the summers of 2017 to 2022. All selected hailstorms had a lifetime of more than one hour, which was divided into three stages: before seeding, during seeding, and after seeding. The statistical t-test was used to test the null hypothesis of no seeding effect. Comparing values before seeding and during seeding, the data support claims that seeding causes an increase in most of the analysed parameters. These can indicate the stimulation of the development of seeded clouds, due to the so-called dynamic effect. After seeding, a decrease in the values of all the parameters analysed was observed (with decreases in average values ranging between 10% to 15%). Furthermore, a spatial analysis of hail kinetic energy shows that areas with values over 300 J/m2 are lower in the protected areas compared to the neighbouring ones where the clouds have not been seeded.