| Popis: |
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. |
