双月刊

ISSN 1006-9895

CN 11-1768/O4

山东夏季两次极端雨强暴雨雨滴谱特征研究
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1.山东省气象防灾减灾重点实验室;2.中国气象科学研究院中国气象局云雾物理环境重点实验室;3.山东省气象台

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国家重点研发计划项目2018YFC1507901,山东省气象局课题(2012sdqx12)


Study on characteristics of raindrop size distribution in two mesoscale convective system with extreme rainfall rate
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    摘要:

    利用Thies激光雨滴谱仪观测的两次极端雨强暴雨雨滴谱资料,结合CINRADA/SA多普勒雷达观测资料,分析了极端雨强对流降水雨滴谱和积分参数特征、以及地面雨滴谱的形成机制,主要结论为:(1)两次过程都是受副热带高压外围西南气流与西风槽共同影响,具有高温高湿的特点,有利于强降水的产生。(2)强对流降水(雨强R>20 mmh-1)雨滴谱参数lgNw、D0与雨强R关系显示,2015年8月3日参数D0随着R增大很快增大,线性拟合线的斜率较大,lgNw随着R增大逐渐减小,线性拟合线的斜率为负值;2017年7月26日D0和lgNw与R都是正相关,但D0和lgNw随着R增大较缓慢地增大,线性拟合线的斜率较小。强对流降水雨滴浓度NT与雨强R之间的关系可以用幂函数拟合,8月3日有较大系数和较小指数,7月26日有较小系数和较大指数。(3)不同雨强的对流降水平均雨滴谱特征显示,8月3日随着雨强增大(R>50 mmh-1),直径1-3mm中小粒子数密度相差不大,直径3-6mm的大雨滴粒子数密度明显增大,对流降水Z-R关系有较大指数(1.61);7月26日随着雨强增大各直径档的粒子数密度基本同时增大,对流降水Z-R关系有较小指数(1.25)。综合各种参数与雨强关系和平均雨滴谱分布特征判断,8月3日强对流降水雨滴谱属于典型的尺寸控制雨滴谱特征,而7月26日对流降水属于浓度-直径混合控制的雨滴谱特征。(4)雨滴谱归一化Gamma函数参数Nw-D0分布显示,两次对流降水具有典型大陆性对流降水雨滴谱特征,对流降水主要属于冰相对流降水雨滴谱,但8月3日过程有较多雨滴谱属于冰相-暖雨混合对流降水雨滴谱特征。

    Abstract:

    Based on data of THIES disdrometer and CINRADA/SA Doppler radar, the raindrop size distribution and integral parameters of convective precipitation in two mesoscale system,whose maximum rain intensity were 483.0 and 418.9mmh-1 respectively, were analyzed. The results shows that:The two precipitation processes wereboth affected by the southwest airflowoutside the subtropical high and the westerly trough withthe characteristics of high temperature and high humidity, which were conducive to the production of heavy rain. On August 3, 2015, the echodeveloped more strongly and was in the mature and weakened stage near the observation point.On July 26, 2017,two linear mesoscale convective echoeswere merged near the observation point, and the echo was in the stage of development and enhancement.In severe convective precipitation episode (rain intensity R>20 mmh-1), for the raindrop concentration (NT), the exponential function can be used to fit theNT with the increase of R. On August 3, there was a large coefficient and a small index, while on July 26, it was just the opposite. For the the median volume diameter of the raindrop, on August 3, D0 rapidly increased with the increase of R, and the slope of the fitting line was large, whilelgNw gradually decreased with the increase of R. On July 26, D0 and lgNware both positively correlated with R, but D0 increased slowly with the increase of R, and the slope of the fitting line was small. For the Z-R relationship, the precipitation on August 3 had a smaller coefficient and a larger index, while the precipitation on July 26 had a larger coefficient and a smaller index. For the characteristics of mean raindrop size distribution of convective precipitation at different rainfall intensities, On August 3, when the rain intensity was more than 100 mmh-1, the particle number density of large raindrops with a diameter of 3-6 mm increased significantly with the increase of the rain intensity. On July 26, the number density of raindrops in each diameter range increased with the increase of rainfall intensity. In conclusion, based on the relationship between integral parameters and rain intensity and the average raindrop size distribution, the precipitation on August 3 was the typical size controlled raindrop size distribution characteristics, while the convective precipitation on July 26 was the concentration-diameter mixed controlled raindrop size distribution characteristics.The NW-D0 distribution of the normalized Gamma function showed that the convective precipitation of the two cases had the characteristics of typical rain drop size distribution of continental convective precipitation. Many raindrop size distribution in the processes of August 3 showed the characteristics of ice phase and warm rain mixed convective precipitation, but most of the convective precipitation in the two processes had the rain drop size distribution characteristics of ice-based.

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  • 收稿日期:2021-06-23
  • 最后修改日期:2022-01-26
  • 录用日期:2022-02-16
  • 在线发布日期: 2022-02-23
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