华北秋季一次低槽冷锋积层混合云宏微物理特征与催化响应分析

A study on macro and micro physical structures of convective-stratiform mixed clouds associated with a cold front in autumn and their catalytic responses in North China

中文关键词:  积层混合云  微物理特征  催化响应  粒子测量系统(PMS)

英文关键词:Convective-stratiform mixed cloud  Microphysical characteristics  Microphysical structure and responses  Particle Measuring System (PMS)

中文摘要:

      利用2013年10月13日机载粒子测量系统（PMS）在张家口涞源地区对积层混合云中上部进行的增雨探测数据，分析了云的垂直微物理结构、云区的可播性和作业前后液态云粒子、冰晶及降水粒子的微物理变化。结果表明，此次降水性积层混合云的垂直结构由冷、暖两层云配置，云层发展厚实，冷云区云粒子浓度平均为62 cm^-3，液态水含量最大0.05 g/m³；2DC和2DP探测的冰晶及降水粒子平均浓度分别为1.9和2.2 L^-1；暖云内云粒子数浓度集中在300 cm^-3左右，液态水含量约0.1 g/m³。探测区域云粒子数浓度的水平分布不均匀。利用云内过冷水含量和冰晶浓度等参数判断，该降水性积层混合云的播撒作业层具有强可播性。对比作业前后云中粒子浓度及平均直径发现，云粒子在作业前时段内的平均浓度为31 cm^-3，远高于作业后平均浓度（17.6 cm^-3）；但平均直径变化不大。作业后冰晶粒子通过贝吉龙过程消耗过冷水长大，浓度由之前的0.86 L^-1增至4.27 L^-1，平均直径也增至550 μm。冰晶粒子逐渐长大形成降水，降水粒子浓度也相应有所升高，谱明显变宽。

英文摘要:

      Making use of the Particle Measuring System (PMS) observations collected in the middle-upper stratocumulus clouds over Laiyuan in Zhangjiakou region on 13 October 2013, the vertical microphysical structure, the seedability of clouds and the variation of total number concentrations of liquid cloud particles, ice crystals and precipitation particles are analyzed. The results show that the clouds have a cold-warm structure with a dry layer and a deep cloud layer. The average value of cloud particle concentrations in cold clouds is 62 cm^-3 and the max value of liquid water content is 0.05 g/m³. The mean concentrations of ice crystals and precipitation particles detected by 2DC and 2DP are 1.9 L^-1 and 2.2 L^-1, respectively. The average value of cloud particle concentrations in warm clouds is 300 cm^-3, and the value of liquid water content is 0.1 g/m³. The horizontal distribution of cloud particle concentrations in the study area is very uneven. Using the value of liquid water content and the mean concentration of ice crystals to identify cloud seeding ability, it is found that stratiform clouds are the most seedable. By comparing the average concentration and diameter of cloud particles before and after the seeding, the results show that the average concentration of cloud particles before the seeding is 31 cm^-3, which is much higher than that after the seeding (17.6 cm^-3). But the average diameter has little change. After seeding, ice crystals can grow by consuming the supercool water. The concentration of ice crystals increased from 0.86 L^-1 to 4.27 L^-1, and the mean diameter also increased to 550 μm. Ice crystal particles gradually grew, and precipitation particle concentration also increased and the particle spectral broadened.