伊宁春季层状云和混合云降水的雨滴谱统计特征分析

Statistical Characteristics of Raindrop Size Distribution for Stratiform and Mixed Cloud Precipitation in Spring in Yining

利用设在伊宁的激光雨滴谱仪获取的2013年4月的降水资料,对层状云和混合云降水粒子谱的微物理参量平均值和Gamma函数拟合结果以及Z-I关系进行对比分析。计算结果表明,伊宁地区春季降水的微物理参量普遍偏小,小滴对降水浓度的贡献达到92%以上,即降水主要以小滴为主。层状云降水的雨强、雨滴数浓度、雨滴的各类微物理特征参量的平均值均大于混合云降水。函数拟合结果表明,混合云降水的雨滴谱宽大于层状云降水的雨滴谱宽,层状云和混合云降水的雨滴谱都比较符合Gamma分布,在小滴段Gamma分布对实际谱都有一定的低估,在大于1 mm的粒径段,拟合结果有一定的偏差。还讨论了雨滴大小因子Λ和形状因子μ之间的关系以及Z-I关系,Λ-μ关系与粒子尺度有关,根据拟合的二项式得到层状云降水粒子的平均直径大于混合云降水的平均直径。

Based on the raindrop size distribution （RSD） data observed with PARSIVEL disdrometer deployed on Yining in April 2013, several microphysical parameters and the Gamma function fitting to raindrop spectra for different rain types （stratiform and mixed cloud） were compared and analyzed. Results show that the microphysical parameters of precipitation in Yining are generally smaller, and the contribution of droplet to precipitation concentration is over 92%, i. e., precipitation is mainly droplet. The rain intensity, raindrop concentration and various mierophysieal parameters of stratiform cloud precipitation are larger than that of mixed cloud, which may be related to the definition of mixed cloud. The fitting results show that the raindrop spectrum width of precipitation in mixed clouds is greater than that of raindrops in stratiform clouds, the raindrop spectra of the stratiform and mixed clouds are all in accordance with the distribution, the droplets is underestimated to the actual spectrum, in the particle size larger than 1 ram, the fitting effect has a certain deviation due to the small number of samples. Finally, the relationship between the raindrops size factor A and shape factor # were studied, which is related to the particle size and can be described by binomial, according to the fitted binomial formula, the result that the average diameter of stratiform cloud precipitation is larger than the average diameter of precipitation in the mixed cloud can also be obtained, the Z-I relationship was also discussed.