郭飞燕,刁秀广,马艳,王宁. 2023. 山东一次飑线双偏振结构与地面降水滴谱特征分析. 气象学报,81(2):328-339. DOI: 10.11676/qxxb2023.20220070
引用本文: 郭飞燕,刁秀广,马艳,王宁. 2023. 山东一次飑线双偏振结构与地面降水滴谱特征分析. 气象学报,81(2):328-339. DOI: 10.11676/qxxb2023.20220070
Guo Feiyan, Diao Xiuguang, Ma Yan, Wang Ning. 2023. Characteristics of the dual-polarization structure and raindrop size distribution of a squall line in Shandong. Acta Meteorologica Sinica, 81(2):328-339. DOI: 10.11676/qxxb2023.20220070
Citation: Guo Feiyan, Diao Xiuguang, Ma Yan, Wang Ning. 2023. Characteristics of the dual-polarization structure and raindrop size distribution of a squall line in Shandong. Acta Meteorologica Sinica, 81(2):328-339. DOI: 10.11676/qxxb2023.20220070

山东一次飑线双偏振结构与地面降水滴谱特征分析

Characteristics of the dual-polarization structure and raindrop size distribution of a squall line in Shandong

  • 摘要: 基于济南双偏振雷达探测资料,并辅以降水现象仪雨滴谱资料和常规实况观测资料,对2021年8月1日山东一次飑线过程的双偏振特征和降水滴谱特征进行了分析,得到以下结论:飑线前侧为宽阔的倾斜上升气流区,低层为强下沉气流区,前侧上升气流区不断有新生单体激发发展,新生单体与主体回波合并发展,飑线后侧单体减弱,在这种较快的循环过程中飑线得以发展、维持、快速前进。前侧新生发展中的单体以少许偏大的液态粒子为主,与主体回波合并发展,具有较高的ZDR柱和KDP柱,液态粒子浓度迅速上升。主体回波后侧冰相粒子下降到湿球0℃层之下出现明显的融化导致ZDRKDP均增大,底层KDP增大更加明显,以高浓度的液态粒子为主,导致强降水。强降水最明显的滴谱特征是粒子浓度高,直径2 mm以下粒子占比较高,降水开始增强时直径1—3 mm的粒子对降水贡献较大且有特大粒子出现,降水最强阶段直径2—4 mm的粒子对降水贡献较大。飑线主体回波低层双偏振参量和雨滴谱存在较好的对应关系, 随着降水增强,ZDR减小而KDP增大,粒子浓度明显升高而直径6 mm以上粒子浓度明显降低。

     

    Abstract: Based on the Jinan dual-polarization radar data combined with raindrop size distribution (DSD) data measured by the Precipitation Phenomenon Instrument (PPI) and conventional observation data, the characteristics of the dual-polarization structure and DSD of a squall line occurred on 1 August 2021 in Shandong province are investigated. Results are as follows: The squall line is characterized by a broad canted updraft area at its leading edge and a strong downdraft area at low levels. Newborn convective cells were continuously triggered and rapidly grew in the updraft area, and achieved intense development by merging with the main echo, whereas the old convective cells in the rear part faded out. These processes continuously cycled within a short time period, which supported the squall line to develop, maintain and move forward rapidly. At the leading edge of the squall line, newborn convective cells were dominated by liquid particles with a few larger particles; in the merging convective cells, the concentration of liquid particles dramatically increased, which induced higher ZDR and KDP columns; at the rear part of the squall line, ice-phase particles melted distinctly as falling down below the freezing level, leading to the increases in ZDR and KDP. In particular, the increase of KDP near the surface was more pronounced, which indicted high concentration of liquid particles that resulted in heavy rain. The most obvious DSD feature for the heavy rain is the high concentration of drops especially the drops smaller than 2 mm. The rain primarily depended on the particles sized 1—3 mm and interfered by a few extra-large particles in the early strengthening stage of rainfall. Nevertheless, particles with 2—4 mm diameter contributed most to the heavy rain in the most vigorous stage of rainfall. The dual polarization parameter with decreasing ZDR and increasing KDP at low levels of the squall line, as rain intensified, corresponded well to the variation of DSDs with significantly increasing particle concentration and distinctly decreasing extra-large particles (>6 mm).

     

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