对流能量计算及强对流天气落区预报技术研究

A CALCULATION OF CONVECTIVE ENERGY AND THE METHOD OF SEVERE WEATHER FORECASTING

文章分析了两种典型的大气湿绝热过程及其处理方法 ,对大气对流能量参数的计算技术进行了研究。结合实际个例 ,利用可逆饱和绝热过程 ,对包含液态水重力拖曳作用的修正对流有效位能 (MCAPE)和修正下沉对流有效位能 (MDCAPE)进行了定量计算。文章结合数值模式输出探空分析 ,预报不稳定和对流能量的区域分布 ,在此基础上建立了综合多指标叠套强对流天气落区预报方法 ,用MM5及国家气象中心T1 0 6模式输出及诊断产品预报强对流天气落区 。

Two methods-pseudo equivalent potential temperature conservation and reversible moist adiabatic process are reviewed to deal with moist adiabatic process. Modified convective available potential energy (MCAPE) is introduced to modify CAPE by presenting the gravitational effect of the condensed liquid water in upward convection. Modified downdraft convective available potential energy (MDCAPE) is defined to modify DCAPE by considering the dragging effect of liquid water. Real case studies show that liquid water plays more significant roles in rising parcel by diminishing CAPE largely than it does in downward flow by increasing DCAPE tenderly. Reversible moist adiabatic process is recommended in calculating MCAPE and MDCAPE. A synthetic multi-indicator superposition method is developed to predict the unstable and severe weather area based on the diagnosis of numerical model output. Experiment shows that the skill is practicable to both MM5 and Chinese National Meteorological Center T106 model outputs.