Analysis on Evolution Characteristics of Hydrometeors in South China Based on Lagrange Tracking Method

Abstract

To reveal the microphysical process of clouds inside a rain cluster and identify the causes of changes in water resources in the air in South China, rain cluster areas with the radar reflectivity factor higher than 40dBZ in a heavy precipitation process in South China were defined as convective cloud cores, and areas with the factor greater than 20dBZ and less than 40dBZ as stratiform clouds around cores with Lagrange tracking method based on S-band dual-polarization radar data. An analysis was conducted on the evolution law of the types of hydrometeor particles and variation characteristics of the raindrop size spectrum in the two areas as well as their differences. The results showed that convective cloud cores and surrounding stratiform clouds were composed of large and sparse raindrops at the early stage of development; the particle crushing process mainly occurred inside stratiform clouds at the mature stage, and the collision-coalescence process mainly occurred at the attenuation stage. Stratiform clouds showed a process of increase in the density of graupel particles at the stage of precipitation enhancement, but the density of graupel particles in convective cores did not change significantly; high- and low-density graupel particles in convective cores had a higher frequency of occurrence than those in stratiform clouds.