激光雨滴谱降水特征分析及谱分布拟合

Analysis of Precipitation Characteristics and Spectrum Distribution Fitting of Laser Raindrop Spectra

  • 摘要: 雨滴谱的研究有利于深入理解云降水的成雨机制和微观特性,为降水数值预报产品的开发提供可行性依据。研究采用2019-2020年河北省77站激光雨滴谱分钟数据,从中选出10场不同等级的降水过程进行统计分析和微物理参量计算,并对谱浓度进行M-P拟合,发现不同量级降水过程的平均雨滴谱数浓度谱分布具有平行相似性。通过分析不同等级降水过程的拟合谱发现,层状云降水过程的雨滴谱可以更好的描述层状云中雨滴的实际分布,相关系数更高,但会导致低估小雨滴,中间尺度雨滴拟合稳定性高,在对流云降水中拟合效果比较差。

     

    Abstract: The study of raindrop size distributions (DSDs) is crucial for a deeper understanding of the precipitation formation mechanisms and microphysical characteristics of clouds. It also provides valuable data and practical experience for the development of numerical precipitation forecasting products. This study utilizes one-minute laser raindrop spectrum data from 77 stations in Hebei Province during 2019–2020. Ten precipitation events of different intensities were selected for statistical analysis and microphysical parameter calculations. The drop size spectra were fitted using the Marshall–Palmer (M–P) distribution. Results show that the average DSDs of precipitation events at different intensity levels exhibit parallel similarity. The stronger the rainfall intensity, the broader the spectral shape and the higher the number density. Most precipitation events exhibit a significant peak in the small-drop region, a distinct concave pattern in the mid-size range, and fluctuations in the large-drop region. The small-drop region also features high number density and steep spectral slopes. The trend of spectral concentration correlates well with rainfall intensity, and their peaks are aligned. The variation of rainfall intensity (R) and radar reflectivity factor (Z) generally shows consistent behavior. During stratiform cloud precipitation, the M–P fitted spectra effectively represent the actual distribution of raindrops, with higher correlation coefficients. However, they tend to underestimate small droplets. The fitting is more stable for mid-size droplets but performs poorly in convective precipitation scenarios.

     

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