东亚中高纬环流对冬季我国东部雾霾天气影响及机理研究

The winter haze happened frequently in recent years, and is gaining more and more attentions. The meteorological factors play important roles in the evolution of haze. This project plans to study the evolution of winter haze and its association with mid-high latitude circulation over East Asia. Based on the spatial and temporal evolution characteristics, the winter haze is classified by using cluster and other statistical methods. The critical synoptic circulation systems in mid-high latitudes are discussed for the different types of winter haze. On the basis of general winter haze, the synoptic characteristics of the persistent severe haze and its possible relation to blocking high as well as atmospheric teleconnections are investigated by using case and synthesis analysis. The relations between Eurasian blocking (e.g., Ural blocking) and cold air as well as precipitation, crucial for the maintenance and extinction of persistent severe haze in eastern China, are investigated under the background of different phase of the North Atlantic Oscillation. The related physical mechanism is going to be set up and also would be verified by using numerical models. This project is expected to establish the physical relation between winter hazes in eastern China and mid-high latitude circulations, thus strengthening the understanding of the mechanisms for the winter haze evolution, which has important scientific value. Moreover, the new results are also expected to improving the predictability of the winter haze in Eastern China, showing crucial application value.

近年来雾霾天气频繁发生，受到越来越多关注。气象条件是影响雾霾天气演变的重要因子，本项目将系统性研究我国东部雾霾变化与东亚中高纬环流的关系。从天气尺度上根据时空演变特点，利用现代统计学方法将雾霾天气分类，分析得到影响不同类型雾霾天气的东亚中高纬关键环流系统。其中特别针对极端强雾霾天气，通过合成和个例分析，探讨其与中高纬持续性环流阻塞高压、大气遥相关型的关系。在不同遥相关型背景下，结合乌拉尔山等地区阻塞高压发展过程中冷空气活动和降水分布特点，对持续强雾霾天气维持和消散等演变阶段进行诊断分析；并利用数值模式对相关物理过程进行机理分析。通过本项目研究，将有望加深对冬季我国东部雾霾天气演变与东亚中高纬环流关系的认识，有一定科学价值；同时也可为提高雾霾天气可预报性提供理论基础，具有重要的应用价值。

冬季我国东部地区雾霾天气频繁发生，冷空气和降水活动是影响雾霾天气演变的重要气象因子。冬季我国冷空气以及降水活动等和上游北大西洋地区环流型演变密切相关。北大西洋涛动正位相（NAO+）维持时，乌拉尔山阻塞活动减弱，影响我国冷空气活动减弱，不利于华北地区大气细颗粒扩散，雾霾天气维持加强。较强NAO+衰减过程中，西太平洋副热带高压位置偏北，我国东部地区偏南风加强，长江中下游地区降水增强，降水湿沉降作用有助于雾霾减弱消散；较弱NAO+衰减过程中，我国东部地区偏南风相对偏弱且位置偏南，降水集中在华南地区。北大西洋涛动负位相（NAO-）衰减转变为北大西洋脊过程中，乌拉尔山阻塞活动加强，影响我国的西路冷空气活动活跃，近地面风加强不利于雾霾天气维持。下游鄂霍次克海阻塞高压也是影响我国中东部地区雾霾的重要环流系统。鄂霍茨克海阻塞阻挡上游天气系统东移，导致贝加尔湖东侧弱高空脊长时间维持，我国东部地区受贝加尔湖高压脊前部弱偏北风影响，有利于华东本地大气细颗粒物积累和北方霾粒子向华东地区扩散。进一步研究表明冬季鄂霍茨克海阻塞高压活动偏强可能和前期热带印度洋暖海温异常有关。综合上述研究结果，本研究为深入探讨冬季我国中东部地区雾霾的气象条件奠定了基础，同时也加深了对冬季我国冷空气活动和降水特征的认识。