一次河南省春季层状云降水的地面雨滴谱特征

Characteristics of the Surface Raindrop Size Distribution of Spring Stratiformis Precipitation in Henan Province

2002年4月4—5日河南省出现了层状云降水天气,临颖、孟津两站进行了地面雨滴谱观测。通过对降水过程中两站的雨滴微物理参量和雨滴谱的对比分析,指出河南层状云降水的雨滴平均直径为10-1mm,雨滴数密度为102个/m3,占雨滴总数较小的大雨滴对雨强的贡献较大。锋前暖区雨滴的平均直径比锋后冷区雨滴平均直径小,雨滴数密度比锋后冷区大,但冷区降水强度大于暖区。在层状云降水过程中,暖区雨滴谱型由宽谱双峰型演变为窄谱单峰型,冷区雨滴谱型由宽谱单峰型演变为窄谱单峰型。雨滴平均直径的起伏暖区要大于冷区,这与暖区中云系结构不均匀及云中对流有关。

The surface raindrop spectra of stratifonnis precipitation on April 4-5,2002 were measured in Mengjin and Linying stations in Henan Province. Through the comparison and analysis of the raindrop microphysical parameters and raindrop size distributions of the two stations during this precipitation process,we find that under the circumstance of stratiformis precipitation in Henan Province, the average diameter of raindrops is 10^-1 mm, the total number density of raindrops 100 drops/ m^3 , and the big size raindrops which account for a small proportion of total raindrops make more contribution to precipitation intensity. The average diameter of raindrops in the warm sector ahead of a cold front is smaller than that in the cold sector behind the cold front;while the total number density of raindrops in the warm sector is greater than that in the cold sector, but the precipitation intesity in the cold sector is higher than that in the warm one. During the process of stratiformis precipitation, the raindrop spectra in the warm sector evolves from a wide spectra double-peak pattern to a narrow spectra single-peak one,while the raindrop spectra in the cold sector changes from a wide spectra single-peak pattern to a narrow spectra single-peak one. The fluctuations of the average diameter of raindrops in the warm sector are larger than those in the cold sector,which is related to the inhomogeneity of the cloud system structure and convection in the cloud.