安宁河谷雨季层状云和对流云降水的雨滴谱特征

Raindrop Size Distribution Characteristics of Stratiform and Convective Precipitation during Rainy Season in Anning River Valley

  • 摘要: 利用2017年8—10月安宁河谷的激光雨滴谱仪观测数据,对层状云和对流云降水粒子谱的微物理参量、Gamma函数拟合、Z-I拟合关系、降水粒子对数浓度和降水强度贡献率进行了分析。结果表明:层状云雨滴谱较对流云窄,对流云降水粒子总数浓度、降水强度、液态水含量和雷达反射率因子等均显著高于层状云。Gamma函数可以较好地拟合雨滴谱的分布情况,层状云的函数曲线较对流云更加平滑。层状云、对流云降水的Z-I拟合关系均较好,分别为Z=181.90I1.54Z=175.59I1.54。层状云降水强度贡献率的80%集中在直径不超过2 mm的粒子,而对流云的90%集中在直径超过1 mm的粒子,表明降水粒子尺度较浓度对降水强度的影响更大,大尺度降水粒子对降水强度贡献更大。

     

    Abstract: Based on the observation data of raindrop size distribution (DSD) in Anning Valley from August to October 2017, the microphysical characteristics, Gamma distribution function, Z-Ifitting relationship, logarithmic concentration of precipitation particles and contribution rate of precipitation intensity of precipitation particle spectrum of stratiform cloud and convective cloud were analyzed. The results show that the DSD spectral width for stratiform precipitation is narrower than that of convective precipitation, and the raindrop concentration, precipitation intensity, liquid water content and radar reflectance of convective precipitation are significant higher than those of stratiform precipitation. The Gamma distribution function can fit the DSD well, and the curve of stratiform precipitation is smoother than that of convective precipitation. The Z-I relation of stratiform and convective precipitation are both well. The Z-I relation of stratiform precipitation and convective precipitation can be respectively written as Z=181.90I1.54 and Z=175.59I1.54. The raindrops with diameter less than 2 mm make the 80% precipitation intensity contribution rate of stratiform precipitation. The raindrops with diameter larger than 1mm make the 90% precipitation intensity contribution rate of convective precipitation. It shows that the precipitation particle size has a greater impact on the precipitation intensity than the particle number concentration, and the large-scale precipitation particles have a greater contribution to the precipitation intensity.

     

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