云微物理过程对黄山云滴谱离散度的影响

利用2008年4—7月、2009年5—8月和2011年5—9月黄山光明顶的云滴谱观测资料，对离散度和体积平均半径之间的关系进行了深入的分析和讨论。结果表明，随着体积平均半径的增大，离散度与体积平均半径之间的相关从正变成负，主要与活化、凝结、蒸发和去活化有关，与以往研究一致。在此基础上，进一步发现负相关比较弱，主要与碰并过程有关。当云雨自动转化阈值函数增大时，碰并增强，离散度与体积平均半径之间的相关性由负转正，且正相关性逐渐增强。碰并导致的正相关削弱了凝结和蒸发导致的负相关。此外，尽管云滴谱出现了双峰谱，但第一档强度(第一档浓度除以总的浓度)仍然可以很好地区分正负相关性。

Effects of cloud microphysical processes on cloud droplet spectral relative dispersion on Mount Huangshan

Cloud droplet spectral relative dispersion is critical to the aerosol-cloud-radiation interaction and the formation of surface precipitation.This study discusses the relationship between relative dispersion of cloud droplet size distributions and volume-mean radius by analyzing the observation data from April to July 2008,May to August 2009 and May to September 2011 at Guangming Peak of Mount Huangshan.This relationship is often used to parameterize relative dispersion.The results show that the relationship between relative dispersion and volume-mean radius changes from positive to negative with the increase of the volume-mean radius,which is mainly related to activation,condensation,evaporation and deactivation,and this is consistent with previous studies.It is further found that the negative correlation is relatively weak,mainly due to collision-coalescence.In addition,when the autoconversion threshold function increases,the correlation between relative dispersion and volume-mean radius turns from negative to positive,and the degree of positive correlation gradually increases due to enhanced collision-coalescence.The positive correlation caused by collision-coalescence offsets the negative correlation caused by condensation and evaporation.In addition,although some cloud droplet size distributions have double peaks,the first bin strength (i.e.,the first bin number concentration divided by the total number concentration) is still able to effectively distinguish their positive and negative correlations.These results will enhance the theoretical understanding of the influencing factors of relative dispersion,which is conducive to the improvement of relative dispersion parameterizations.