东亚组织化对流的积云参数化方案构造研究

The phenomenon of organized cumulus convection has been confirmed by amount of observations, but the current cumulus parameterization schemes of current numerical models have not descriptive mechanism of cumulus organized convection, thus the prediction and simulation about the organized convective precipitation need to be improved. In this project, the typical organized convection precipitation will be simulated and diagnosed, and the environmental conditions and convective features of organized convection will be analyzed. In attention, dynamical factor as the dynamical control of parameterization scheme will be diagnosed, which can be used to indicate the organized convection. The cumulus parameterization scheme will be developed, which is suitable for the simulation of the organized convective precipitation in East Asia. This research will deepen understanding of the interactions of multi-scale systems and reveal the feedback mechanisms between cumulus convection and large scale environment. The developed scheme will be used in WRF model so as to improve the prediction and simulation about the organized convective precipitation in East Asia.

积云对流组织化现象已为大量观测事实所证实，而目前数值模式中通用的积云参数化方案缺乏描述有组织积云对流过程的机制，对东亚有组织对流降水模拟预测能力有限。本项目针对东亚有组织对流降水典型个例，诊断分析东亚有组织对流降水的环境条件及对流组织化特征，寻找到指示对流组织化特征的动力因子，作为参数化方案的动力控制，发展和构造适合于东亚有组织对流的积云参数化方案。本项目研究将加深积云对流引发多尺度系统相互作用的理解，揭示积云对流对大中尺度环境反馈物理机制，发展后的方案将植入WRF中尺度模式，提高东亚有组织对流降水过程的模拟及预测能力。

根据我国有组织积云对流降水的特点，发展和改进了一种适合于描述东亚有组织对流降水的积云参数化方案。首先，在分析和比较目前通用的中尺度参数化方案对东亚降水模拟基础上，选择Kain-Fristch eta 作为发展和改进的目标方案；其次，针对1990-2010年来梅雨锋上有组织降水的合成统计分析，提取出有组织降水的关键动力因子；再次，将该关键动力因子作为积云参数化的动力控制；同时改进了积云参数化的闭合假设条件，以此来改进Kain-Fristch积云参数化方案；最后，利用改进的参数化方案对东亚典型的组织化降水过程—梅雨锋降水、华南前汛期降水、华北汛期、台风降水进行了数值模拟。结果表明：改进后的方案对四种类型暴雨的模拟都优于原方案，不仅表现在模拟暴雨雨带的移动变化和强度上，而且表现在模拟暴雨降水落区和降水分布上。本项目的研究将提高东亚有组织对流降水过程的模拟及预测能力，具有十分重要的科学意义。