南方不同类型冰冻天气的大气层结和云物理特征研究  

Characteristics of Atmospheric Stratification and Cloud Physics of Different Types of Freezing Rain over Southern China

作　　者：陶玥[1] 李宏宇[2] 刘卫国[1] 

机构地区：[1]中国气象科学研究院中国气象局人工影响天气中心,北京100081 [2]北京市人工影响天气办公室,北京100089

出　　处：《高原气象》2013年第2期501-518,共18页Plateau Meteorology

基　　金：国家自然科学基金项目(40905059);国家自然科学基金项目(41075099);中国气象科学研究院基本科研业务费专项资金项目(2008Y001);中国气象科学研究院基本科研业务费专项资金项目(2011Z005)共同资助

摘　　要：利用观测资料和CAMS中尺度云分辨模式,对南方3次不同类型冻雨天气过程进行模拟,重点研究了冰冻天气中冻雨区云系宏、微观结构及大气层结特征,初步分析了冻雨形成的云物理机制。结果表明:(1)逆温层的存在是冻雨发生的必要条件,低层湿度较大的逆温常与冻雨天气有关。3次冻雨过程的冻雨区都存在逆温层,其中第一、二次过程属于锋面逆温,而第三次过程属于平流逆温。可见,逆温层结有利于冻雨的发生,但逆温层的存在仅是形成冻雨的条件之一。冻雨的发生还与水汽(湿度)、风向风速、地面特征有关。低层有水汽输入到冻雨区、地面温度等于或低于0℃,有利于冻雨形成和过冷雨水的冻结。(2)冻雨的形成需要满足3个主要条件:在对流层中高层存在冻结层,冻结层下要有暖层和逆温层,近地层有一个温度<0℃的冷却层,并且低层的冷却层相对湿度较高。中高层冻结层主要产生冰相降水粒子,中层的暖层可以确保上层降落下来的固态降水粒子(雪或霰)融化成雨滴或在融化层中直接产生液态降水。这样,雨滴下降到低空冷却层后会逐渐变成过冷雨滴,当过冷却雨滴接触到<0℃的地面或者其他物体表面时,迅速冻结形成冻雨。(3)不同冻雨区上空存在2种不同类型的云,对应云中有2种明显不同的温度层结:混合相云中的"冷-暖-冷"层结和水云中的"暖-冷"层结。具有2种不同层结特征的不同冻雨区云系,对应2种不同的微物理结构,具有2种不同的冻雨形成的云物理机制。(4)同一类型天气系统中的冻雨区,可以存在不同的温度层结、云的微物理结构和冻雨形成的机制;不同类型天气系统也可以存在特征相同的冻雨区,即冻雨形成的温度层结、云的微物理结构和冻雨形成的物理机制都相同。Three classical freezing rain processes over southern China were simulated by observation data and CAMS mesoscale cloud model. Characteristics of atmospheric stratification and cloud physics of the freezing rain and mechanism of freezing rain formation are analyzed. The results show that： （1） a necessary condition for exist freezing rain was the presence of the temperature inversion layer. The inversion layer with high humidity in lower atmosphere often associated with freezing rain. （2） Formation of freezing rain needed to meet three main conditions： freeze layer existed in the upper troposphere, a warm layer and temperature inversion layer existed blow the freeze layer, and cooling layer （temperature below 0℃） with high humidity existed near the surface. （3） Two different types of temperature stratification were existed during freezing rain, which are ‘cold-warm-cold＇ and ＇warm-cold＇ stratification. Corresponding to two types of stratification, two different clouds microphysical structures were existed and two different mechanism of freezing rain formation. Consideration of stratification （‘cold-warm-cold＇ layer）, the cloud thickness was deeper over Hunan Province on 28 January 2008 and Jiangxi Province on 5 January 2010, and cloud has large amount of ice-phase particles. So clouds belonged to mixed-phase cloud. Freezing rain over Hunan and Jiangxi Provinces was formed by ice-crystal mechanisms （the melting process）. That is, freezing rain developed as falling snow encountered a layer of warm air then the snow completely melted and be- came rain. As the rain continued to fall, it passes through a thin layer of cold air just above the surface and cools to a temperature below freezing and formed supercooled drops. When the supercooled drops strike ground, or anything else below 0℃, they instantly freeze, forming freezing rain. Clouds above freezing rain area over Hunan and Jiangxi Provinces belonged to mixed-phase cloud. However, clouds above freezing rain area over Gui

关 键 词：冻雨 云物理特征 大气层结 

分 类 号：P401[天文地球—大气物理学与大气环境]