2003年春季陕西省层状云降水的雨滴谱特征

Characteristics in Size Distribution of Raindrops of Stratiform Precipitation in Spring 2003 of Shaanxi Province

文章给出了陕西省春季(2003年)层状云降水雨滴谱部分特征,这些特征与降水天气系统密切相关。降水产生于混合云,各层系统配置适当,有较厚冷层云和相接的暖层云,雨滴数浓度大可达10~3m^(-3),雨滴谱较宽可达0.32 cm。反之数浓度较小(10~2m^(-3),谱较窄(0.22 cm)。其中直径0.1 cm以下雨滴谱约占总浓度的80%以上,而对雨强的贡献小于20%。0.1～0.2 cm雨滴是雨强的主要分量,它平均占48%～77%。雨滴谱多数呈非单调下降分布,三参数分布n(D_i)=n_0D~αe^(-λD)明显优于指数分布n(D_i)=n_0e^(-λD)。

Some features of raindrop spectrum in stratiform clouds in spring 2003 of Shaanxi were observed and analyzed in this paper, which are closely associated with precipitating weather systems. The precipitat- ing mixed clouds with deeper cold and warm cloud layers have an appropriate level configuration, and their raindrop number concentrations are bigger up to 103 m 3 and the spectra of raindrops are wider up to 0.32 cm. Conversely, the stable clouds have a smaller number concentration （102 m-3） and a narrower spectrum width （0.22 cm）. The raindrops under 0.1 cm in diameter accounted for more than 80% of the total concentration, while the contribution to rainfall intensity is less than 20%. Actually, the 0. 1- 0.2 cm across raindrop is a major component of rainfall intensity, which accounted for an average 48%-- 77 %. The majority of raindrops had a non-monotonic decreased spectral distribution, and the three-param- eter fitting formula n（Di） = n0 Dn e-D is better than the exponential distribution n（Di） = no e-D.