Dual Polarization Parameters and Precipitation Particle Spectrum Characteristics of a Spring Hail Event in Southwestern Fujian
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Abstract:
Using the S-band dual polarization radar data and the surface precipitation phenomenon instrument data, the process of a hailstorm with severe convective weather in Yongding District of Longyan, Fujian Province on 27 March 2020 is analyzed, and compared with the characteristics of short-term heavy precipitation that occurred in Zhangping of Longyan at a similar time. The results show that the echo height of hail cloud in Yongding jumped before the hail shooting.There was a bounded weak echo in the front of the cloud moving direction, and the ZDR arc with an intensity of 2-4 dB also appeared there. The KDP column developed highly within the hailstorm simultaneously, up to 7-8 km. The KDP column also appeared in the heavy rainfall cloud in Zhangping, but its height 〖JP2〗was lower. There were hailstones aloft in Zhangping, but heavy rainfalls with large raindrops appeared on the ground for hailstones melting during falling. In the front of these two severe convective clouds, the large drop (>3 mm) ends increased firstly with raindrop spectrum boarding, showing double or multi-peaks. While the strong center of convective cloud was moving closer, the concentration of small rain drops (≤1 mm) increased in magnitude, which was related to the separate fall tracks of large and small raindrops caused by the strong environmental vertical wind shear in the front of convective cloud. In the hail shooting or heavy precipitation stage, the hailstones had low density and the raindrop spectrums showed weak double peaks at Yongding Station, while single-peak presented at Zhangping Station. The large drops at the two stations in this stage were mostly caused by the melting from small hails. The double-peak structure of the raindrop spectrum after hail shooting was mainly caused by the collision of raindrops. The raindrop spectrums at the tail of the cloud became narrow, decreasing in magnitude with small particles.