2021年夏季长白山麓雨滴谱分布特征

Distribution Characteristics of Raindrop Spectrum at Changbai Mountain Foothills in Summer of 2021

  • 摘要: 利用2021年6—8月吉林靖宇Parsivel2型雨滴谱观测数据,研究长白山麓夏季不同降水类型和不同降水强度条件下雨滴谱特征,并与国内外研究对比。结果表明:长白山麓夏季降水雨滴直径对降水量贡献呈先增大后减小的趋势,贡献较大的直径区间为0.812~2.375 mm,随着降水强度增大,大雨滴(直径D≥2.75 mm)对降水量贡献也增大;对流降水比层云降水的雨滴谱更宽,雨滴数浓度及平均直径也更大;与国外经典对流降水雨滴谱相比,长白山麓对流降水标准截距参数lgNw及质量等效直径Dm特征更接近海洋型降水,与北京延庆及大兴、安徽滁州、江苏浦口相比,长白山麓夏季降水雨滴具有较小的直径和较大的数浓度;长白山麓夏季对流降水和层云降水反射率因子Z与降水强度R拟合关系分别为Z=290.64R1.27Z=193.36R1.65,经典Z-R关系对该地区降水估测存在低估;形状参数μ、斜率参数Λ存在较好的二项式拟合关系。

     

    Abstract: In order to better understand the distribution characteristics of raindrop particle spectrum at Changbai Mountain foothills in summer, the raindrop size distribution with different rainfall types and different rainfall intensities are analyzed based on the observations of Parsivel2 disdrometer at Jingyu, Jilin Province from June to August in 2021. The distribution characteristics of raindrop spectrum are also compared with relevant research results at home and abroad. The results show that the frequency of stratiform cloud rainfall is much higher than that of convective rainfall (88.16% vs 11.84%) in summer at Changbai Mountain foothills, but convective rainfall contributes more to the total rainfall intensity (47.78% vs 52.22%). The contribution of raindrop diameter to rainfall in summer increases first and then decreases, while the diameter of raindrop makes a greater contribution to rainfall ranging from 0.812 mm to 2.375 mm. For large particles (diameter D≥2.75 mm), the contribution of raindrops to rainfall also increase as rainfall intensity increasing. The spectra of convective rainfall has a larger spectrum width, mean number concentration and mean diameter than stratiform precipitation. The Gamma fitting curve underestimates the number concentrations of raindrops larger than 4.25 mm, especially for weak precipitation. Comparing with classical convective raindrop spectra, the normalized intercept parameter lgNw and the mass equivalent diameter parameter Dm of convective rainfall at Changbai Mountain foothills are closer to the oceanic-like cluster. The summer raindrops here have smaller diameter and higher number concentration compared with those of Yanqing and Daxing in North China, and Chuzhou and Pukou in East China. The reflectivity factor Z and rain rate R fitted relationships between convective rainfall and stratiform rainfall at Changbai Mountain foothills are Z=290.64R1.27 and Z=193.36R1.65, respectively. The rainfall of estimation using classical Z-R relationship (Z=300R1.40) is underestimated in this area, especially for heavy rainfall. The shape parameter μ and the slope parameter Λ of Gamma fitting function satisfy binomial relationship, while the parameter Λ increases with the increase of parameter μ. Besides, the shape parameter μ of raindrop spectrum at Changbai Mountain foothills is less than that in North China, East China and South China on the whole, when the slope parameter Λ is equal.

     

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