Vertical Variability of the Raindrop Size Distribution in Typhoons Observed at the Shenzhen 356-m Meteorological Tower

Abstract

Raindrop size distribution (DSD) characteristics at various altitudes in two landfalling typhoons in 2017 (Hato and Pakhar) were investigated by using laser optical disdrometers mounted at four altitudes (10 m, 40 m, 160 m and 320 m) of the Shenzhen 356-m meteorological tower. Significant differences of the DSD and derived parameters, mass-weighted mean diameter (Dm), normalized intercept parameter (NW), and standard deviation of the mass distribution σm, were observed at different altitudes for the two typhoons, while the rainwater content between the four altitudes had not statistically significant differences. The low-altitude DSDs had more mid-size drops (1 < D < 3 mm), fewer large drops (D > 3 mm), and narrower distribution widths than the high-altitude ones, while the concentration of small drops varied nonlinearly with height. The value of NW decreased with height, while Dm and σm increased with height. The gamma distribution parameters, N0, μ and Λ, are found to increase with decreasing height. Both the derived μ–Λ and Z–R relations were significantly varied in different altitudes.