热带深对流云砧数值模拟及云凝结核数浓度对其影响的初步试验

利用中国科学院大气物理研究所发展的三维强风暴模式，对Egrett Microphysics Experiment with Radiation Lidar and Dynamics（EMERALD）试验期间的一次长寿命热带深对流个例进行对流产生、发展、消亡过程以及云砧的数值模拟，并与实测资料［包括C波段双线偏振雷达图像资料、机载云粒子成像仪（CPI）探测的云砧卷云微物理特性以及激光雷达探测的云砧宏观特性资料］进行了细致的对比，然后通过改变模式中最大云滴数浓度进行有关云凝结核数浓度影响云砧卷云冰晶含水量和数浓度的敏感性试验。模式较好地模拟出系统的一些重要宏观特征，如爆发性增长阶段、各高度雷达水平反射率因子的最大值、对流云主体移动方向、云砧底部和顶部高度。对云砧冰相粒子含水量、数浓度以及平均直径等微观特征的模拟结果与实测也比较接近。对于本文个例而言，异质核化为冰晶形成的最主要方式，其次为过冷云滴的均质核化。敏感性试验结果表明:当云凝结核数浓度增加时，爆发性增长阶段的垂直速度减小，使得对流云从中低层向高层的水物质输送量减少，从而使云砧卷云冰晶的数量减少。

Numerical Modeling of Tropical Deep Convective Anvil and Sensitivity Test on Its Response to Changes in the Cloud Condensation

The three-dimensional strong-storm cloud model developed by the Institute of Atmospheric Physics,Chinese Academy of Sciences,is used to simulate the formation,growth and decay of a deep,long-lasting tropical convective system and its anvil,observed during the Egrett Microphysics Experiment with Radiation Lidar and Dynamics(EMERALD) campaign.The simulation results are compared in detail with observations which include C-band dualpolarized radar images,microphysical properties of cirrus cloud probed by cloud particle imager(CPI),as well as macroscopic characteristics measured by polarization lidar.Furthermore,the response of water content and number concentration of ice crystals in the anvil cirrus cloud to changes in the cloud condensation nuclei concentration has been assessed by increasing the maximum concentration of cloud droplets. The most important macro features of the system,such as the phase of explosive growth,the maximum horizontal radar reflectivity at different levels,the movement of the convective core,the base and top of the anvil,are well reproduced by the model.In addition,the model is able to reproduce the micro characteristics of the anvil,such as the water content,the number concentration and mean diameter of ice particles.Our simulation shows that heterogeneous nucleation dominates the formation of ice crystals,while homogeneous nucleation also plays a role during this process.Sensitivity test indicates that higher cloud condensation nuclei concentration leads to lower vertical velocity at the phase of explosive growth,leading to less vertical transportation of water substance from lower and middle level to upper level,and in turn,to a lower number concentration of ice crystal in the anvil cirrus cloud.