青藏高原东南部不同地区的雨滴谱特征研究

Characteristics of Raindrop Size Distribution in Different Areas of Southeastern Tibetan Plateau

  • 摘要: 利用2019年5~8月青藏高原东南部石渠、新龙和泸定站雨滴谱资料,在对比分析3个地区不同雨强和不同降水类型雨滴谱特征的基础上,确定了降水的反射率因子–雨强(ZR)关系和谱形状–斜率( \mu \Lambda )关系,探讨了高原东南部与我国其他地区雨滴谱的差异。结果表明:青藏高原东南部地区雨滴数浓度随雨强增大而上升,石渠在相同雨强下可以产生少量更大的雨滴,中大雨滴的数浓度由大到小依次为石渠、新龙、泸定。Gamma模型对青藏高原东南部层状云和对流云降水雨滴谱的模拟效果均较好,对流云降水雨滴谱明显较层状云降水更宽且斜率更小。层状云降水ZR关系基本一致,而对流云降水在相同R下对应的Z值由大到小依次为石渠、新龙、泸定; \mu –\Lambda 关系也基本一致,符合二项式关系。青藏高原东南部层状云和对流云降水中的平均 N_w 小于国内其他地区,其中,石渠对流云降水的平均 D_m 最大而平均 N_w 最小。

     

    Abstract: Based on the raindrop size distribution (RSD) data obtained in the Shiqu, Xinlong and Luding sites of the southeastern Tibet Plateau from May to August 2019, the raindrop spectrum characteristics of different rainfall intensities and different precipitation types in three regions were compared and analyzed. The relationships between reflectivity (Z) and rain rate (R), as well as the shape parameter (\mu) and the slope parameter (\Lambda)were determined, the difference of raindrop spectrum between the southeast of Tibetan Plateau and other regions in China was discussed. The results show that the number concentration increased with the increasing rain intensity. A small amount of larger raindrops could be produced under the same rain intensity in Shiqu, and the number concentration of medium and large raindrops from large to small was Shiqu, Xinlong, Luding. The Gamma model had a good simulation effect on the raindrop spectrum of stratiform cloud and convective cloud in the southeast of Tibetan Plateau. The raindrop spectrum of convective cloud was significantly wider and the slope was smaller than that of stratiform cloud. The Z–R relationship of stratiform precipitation was basically consistent, while the corresponding Z values under the same R in convective precipitation were Shiqu, Xinlong, Luding in descending order. And the \mu \Lambda relationship was also basically the same, which fit well with the binomial relationship. The average N_w of stratiform and convective precipitation in the three areas was smaller than that in other areas of China, and the average D_m of convective precipitation in Shiqu was the largest, but the average N_w was the smallest.

     

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