热带对流活动日变化的模拟研究

利用一个云分辨与海洋的耦合模式，模拟研究了热带对流活动的日变化.通过对模拟结果的分析，揭示了热带地区不同海温日变化条件下，对流活动的云物理特征.利用热带海洋与全球大气响应观测实验（TOGA COARE）的观测资料作为模式的初始与边界场，来驱动耦合模式.对热带海表温度按照其日变化幅度的大小进行了分类，分为强、弱海表温度日变化两种类型，并在此基础上进行了合成分析.结果表明：1）在弱的海表温度日变化下，云中的云冰含量大于云水含量，说明云中以层状云为主；而在强的海温日变化下，云中的云水含量大于云冰含量，说明云中以 关键词： 热带对流日变化 地面降水率 云冰含量 云水含量

Simulation of the diurnal variation of the tropical convection

The diurnal variation of the tropical convection is investigated using hourly outputs from a two-dimensional cloud-resolving model simulation. The features of cloud microphysics in tropical convections are proposed by the contrastive analysis of the simulation. The model is forced by the observational data obtained from tropical ocean global atmosphere coupled ocean-atmosphere response experiment as the initial and boundary fields. The diurnal composites are carried out in weak diurnal SST variations （case W） and strong diurnal SST signals （case S） according to the amplitude of diurnal SST variations. The simulation results show that the ice water path in case W is larger than the liquid water path in case S, and more water cloud and less ice cloud exist in case W than in case S. The results also show that the surface rain rates reach their peaks in the early afternoon in case S, while the surface rain rates reach their peaks in the night in case W. Further comparison of cloud microphysics budgets shows that the coagulation of precipitation ice （sum of snow and graupel） is less than the coagulation of liquid water （sum of cloud water and precipitation water） and ice cloud can be formed in case W.