2021, 32(3): 370-384.
DOI: 10.11898/1001-7313.20210309
Abstract:
Based on the data of PARSIVEL disdrometer, particle phase identification and reflectivity factor of CINRAD/SA-D dual polarization weather radar, a hailstorm process occurred in northern Shandong Province on 16 Aug 2019 is analyzed. The rain and hail particles are distinguished, and the evolution of the raindrop size distributions is analyzed. PPI scans at 0.5°elevation of dual polarization weather radar show that there are raindrops at Dezhou and Lingxian observational stations, while it rains heavily and hails at Linyi. As for PARSIVEL disdrometer, a small number of ice particles is identified at all three sites, and the distribution of ice particles varies dramatically. Raindrops are classified into rain or ice particles according to the particle size and falling speed. However, the observational results still need artificial verification. When the hailstorm passes over the three observational stations, ice particles are identified by PARSIVEL disdrometer. At Dezhou station, 5 ice particles are identified, including 2 large hailstones (diameter > 8 mm), 2 small hailstones (diameter between 5-8 mm) and 1 graupel particle (diameter between 2-5 mm). There are 29 ice particles in Lingxian station, including 2 large hailstones, 19 small hailstones and 8 graupel particles. At Linyi station, 17 ice particles are observed, including 10 large hailstones, 3 small hailstones and 4 graupel particles. The Z-R relation retrieved by PARSIVEL disdrometer data is Z=1523R1.21, which has a larger coefficient, but a smaller index compared with the Z-R relation of convective precipitation of the new generation Doppler radar. In the stage of increasing rain intensity in front of hailstorm, the raindrop size distributions feature low number density of small raindrops and more large raindrops, therefore the total raindrop concentration is low, and the radar reflectivity is high. Meanwhile, in the stage of rain intensity weakening, the concentration of small raindrops with a diameter less than 3.0 mm increase significantly, while that of large raindrops is relatively small. Consequently, the total raindrop concentration increases significantly with low radar reflectivity. Furthermore, there are fewer small raindrops and more large raindrops in the vicinity of the main updraft region of hailstorm, the raindrop concentration is low, and the mass weighted diameter Dm and reflectivity factor Z are high. In the downdraft region of the hailstorm, more small raindrops lead to higher total raindrop concentration and small Dm and Z.
Wang Jun, Wang Wenqing, Wang Hong, et al. Hydrometeor particle characteristics during a late summer hailstorm in northern Shandong. J Appl Meteor Sci, 2021, 32(3): 370-384. DOI: 10.11898/1001-7313.20210309