Study on the Evolution Characteristics of Hail Embryos in Weining, Guizhou, Based on X-band Dual Linear Polarization Radar

In order to explore the evolution characteristics of hail embryo particles during hailstorm in Weining area, the Barnes interpolation method was used to interpolate polarization parameters after unfolding, filtering, and adaptive attenuation correction of X-band dual polarization radar data. The fuzzy logic algorithm was used to identify the particles of the aquatic objects, and two typical hailstorm processes in Weining County were then systematically analyzed. The following conclusions were obtained: (1) The sources of high-density graupel were aggregates and frozen drops during both processes, and the sources of low-density graupel particles were ice crystal. High-density graupel particles contributed the most to the production of hail during a single-cell hailstorm, while low-density graupel particles contributed the most to the production of hail during a multicell hailstorm. (2) In a multicell hailstorm, the high-altitude convergence and low-level divergence of the attenuating cell promote the formation of hail embryos in developing cell. (3) Before landfall of hail for a single-cell hailstorm, the number of low-density graupel particles is almost unchanged. Due to the increase of aggregates, the rate of consumption of supercooled water particles is accelerated, resulting in a decrease in supercooled water particles. Moreover, some high-density graupel particles fall to the ground, eventually leading to a decrease in the number of high-density graupel particles, the number of distance pools decreases by 10 per min (pool is the number of pools of aqueous particles in the particle recognition result). During hailfall, high-density graupel particles attach to supercooled water particles and then grow to form hail, resulting in a decrease in high-density graupel particles and a 12.1 reduction in the number of distance pools per min. Under the “Bergeron process” (Namely Wegener-Bergeron-Findeisen process, referred to as WBF)and the adhesion of the aggregation, the number of low-density graupel particles rapidly increases, with a rate of increse by 36 pools per min. After hailfall, low-density graupel particles fall, and the number rapidly decreases, with a rate of reduction by 36.6 pools per min. During the descent process, low-density graupel particles that are attached to supercooled water, aggregates, etc., are converted into high-density graupel particles, resulting in the total amount of high-density graupel particles is almost unchanged, and the number of distance libraries increased per min is 2. (4) Multicell hailstorms are similar to single-cell hailstorms before the fall of hail, except that the development speed, number of hail embryos, and echo intensity of the single-cell hailstorm are higher compared with that of the single-cell hailstorm under the promotion of dissipating cells. During hailfall, low-density graupel particles attach to supercooled water droplets and then form into hail during the falling process, resulting in a rapid decrease in the number of low-density graupel particles, the number of distance pools reduced per min is 62.6. On the other hand, The number of high-density graupel particles increase 16.5 distance pools per min. The time from mature phase to hailfall in a multicell hailstorm is about 15 min longer than a single-cell hailstorm. The situation are similar for both processes after the hailfall. (5) Based on the analysis of the hailstorm mechanism in Weining area, the conceptual models of single-cell hailstorm and multicell hailstorm were established, respectively. This paper studies the evolution characteristics of hail embryos in each process of two typical hailstorms and obtains preliminary results, which has high application value for hailstorm early warning, prediction, and artificial hail suppression.