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

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.