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Precipitation Microphysical Processes in the Inner Rainband of Tropical Cyclone Kajiki (2019) over the South China Sea Revealed by Polarimetric Radar
Advances in Atmospheric Sciences ( IF 5.8 ) Pub Date : 2020-12-23 , DOI: 10.1007/s00376-020-0179-3 Hepeng Zheng , Yun Zhang , Lifeng Zhang , Hengchi Lei , Zuhang Wu
Advances in Atmospheric Sciences ( IF 5.8 ) Pub Date : 2020-12-23 , DOI: 10.1007/s00376-020-0179-3 Hepeng Zheng , Yun Zhang , Lifeng Zhang , Hengchi Lei , Zuhang Wu
Polarimetric radar and 2D video disdrometer observations provide new insights into the precipitation microphysical processes and characteristics in the inner rainband of tropical cyclone (TC) Kajiki (2019) in the South China Sea for the first time. The precipitation of Kajiki is dominated by high concentrations and small (< 3 mm) raindrops, which contribute more than 98% to the total precipitation. The average mass-weighted mean diameter and logarithmic normalized intercept are 1.49 mm and 4.47, respectively, indicating a larger mean diameter and a lower concentration compared to the TCs making landfall in eastern China. The ice processes of the inner rainband are dramatically different among different stages. The riming process is dominant during the mature stage, while during the decay stage the aggregation process is dominant. The vertical profiles of the polarimetric radar variables together with ice and liquid water contents in the convective region indicate that the formation of precipitation is dominated by warm-rain processes. Large raindrops collect cloud droplets and other raindrops, causing reflectivity, differential reflectivity, and specific differential phase to increase with decreasing height. That is, accretion and coalescence play a critical role in the formation of heavy rainfall. The melting of different particles generated by the ice process has a great influence on the initial raindrop size distribution (DSD) to further affect the warm-rain processes. The DSD above heavy rain with the effect of graupel has a wider spectral width than the region without the effect of graupel. 本文利用双偏振雷达和二维视频雨滴谱仪的联合观测,首次分析了南海“剑鱼”热带气旋内雨带降水的微物理特征和过程。热带气旋“剑鱼”降水主要以高浓度的小雨滴(直径小于3 mm)为主,其对降水的总贡献超过98%。雨滴的平均质量加权直径和取对数的标准化截距参数分别为1.49 mm和4.47, 相比登陆华东地区的台风,降水的雨滴直径更高,浓度更低。在“剑鱼”内雨带发展的不同阶段,冰相过程变化显著。在雨带的成熟期,冰相过程中淞附过程占主导,而在雨带的消散期,以丛集过程为主。对流区域的双偏振变量以及冰水和液态水含量的垂直剖面表明降水以暖雨过程为主。大雨滴在下落过程中碰并收集小雨滴和云滴,使得雷达反射率因子、差分反射率因子和差分相移率随高度的递减而增加,即雨水收集云水和碰并过程在形成强降水时发挥重要作用。冰相过程产生的冰相粒子的融化直接影响融化层下方的雨滴谱分布,进而影响其下的暖雨过程。在强降水上方,相比不受霰粒子影响的区域,受霰粒子影响区域的高空雨滴谱的谱宽更宽。
更新日期：2020-12-23
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