南昌市三类降水雨滴谱特征分析

Analysis of raindrop spectrum characteristics of three types of precipitation in Nanchang City

为了更深入了解南昌市三类降水的变化,使用南昌市DSG5型降水现象仪的雨滴谱观测数据,以及自动气象站小时降水、雷达回波等数据,采用雨滴谱数据算法、雷达回波分析和Gamma函数拟合等方法,对2019年49月南昌市雨滴谱观测数据进行分析。结果表明:南昌市降水粒子平均直径为0.5~0.6 mm,积状云降水最大,层状云降水最小;雨强的大小与粒子数浓度和平均直径有关,主要由粒子数浓度决定;积状云降水、层状云降水和层积混合云降水三类降水对应三种回波类型和回波结构;小雨滴占比均超过97%,且无论是雨强还是雨滴数浓度,小于1 mm的雨滴贡献值均最大;三类降水雨滴谱Gamma分布曲线趋势基本一致,其中积状云降水在小雨滴段拟合较好,层状云降水在中间段拟合较好,层积混合降水整条曲线的拟合值与真实值都较为接近,拟合效果最佳。

In order to gain a deeper understanding the changes of three types of precipitation in Nanchang City,the raindrop spectrum observation data from the Nanchang DSG5 precipitation phenomenon instrument,as well as hourly precipitation data from automatic weather stations and radar echoes were used.Raindrop spectrum data algorithm,radar echo analysis,and gamma function fitting were used to analyze the raindrop spectrum observation data from April to September 2019 in Nanchang City.The results show that the average diameter of precipitation particles in Nanchang City is 0.50.6 mm,with the largest precipitation in cumulus cloud and the smallest precipitation in layer cloud.The magnitude of rain intensity is related to the particle number concentration and average diameter,mainly determined by the particle number concentration.The three types of precipitation,namely cumulative cloud precipitation,layered cloud precipitation,and cumila tive and layer mixed precipitation,correspond to three types of echo types and echo structures.The proportion of small raindrops exceeds 97%,and regardless of rain intensity or raindrop number concentration,raindrops smaller than 1 mm have the most contribution value.The Gamma distribution curves of the three types of precipitation raindrop spectra are basically consistent,with the cumulus cloud precipitation fitting well in the small raindrop segment,the layer cloud precipitation fitting well in the middle segment,and the fitted values of the entire curve of the cumulative and layer mixed precipitation are close to the true values,indicating the best fitting effect.