近36a来四川盆地持续霾事件特征及环流分析

利用1981~2016年四川盆地102个气象观测站逐日霾日观测资料，对四川盆地持续霾事件（定义为连续3d及以上有烟幕或霾发生的天气）的时空分布特征、变化趋势进行分析，然后对冬季霾事件环流场特征进行研究.结果表明：1981~2016年四川盆地持续霾事件的年平均日数呈增加趋势，持续霾事件日数占霾总日数的百分比与霾总日数增加趋势较为一致，霾总日数的增加主要是由持续霾事件的增加引起的.四川盆地持续霾事件的空间分布不均匀，与霾日数的大值区的分布较为一致，主要集中在川东北城市群、成都平原城市群以及川南城市群.持续霾事件多发区的范围在1981~2010年呈年代际增大，在2011~2016年范围减少显著.通过分析盆地冬季霾事件的环流场发现，霾事件偏多（少）年时段，四川盆地处于暖（冷）高（低）压大值区域，乌拉尔山阻塞高压偏弱（强），东亚大槽偏弱（强），盆地上空为一定程度的辐合（辐散），存在（不存在）明显逆温结构，垂直上升运动弱（强），这些条件均有利于污染物颗粒聚集在浅薄的边界层内（利于污染物的扩散），造成霾天气的维持（消散）.

Characteristics of persistent haze events and circulation analysis in Sichuan Basin in recent 36years

Based on the statistical haze data over Sichuan Basin during 1981~2016, the climatic characteristics of spatial and temporal distribution of persistent haze days, which refer to the haze events lasting 3 or more days and the circulation of typical haze process are analyzed. The results show that the annual average days of persistent haze events in Sichuan from 1981 to 2016 showed an increasing trend, the percentage of continuous haze days to total haze days was consistent with the increasing trend of total haze days, the increase of total haze days was mainly caused by the increase of continuous haze events. The spatial distribution of persistent haze events of Sichuan Basin was heterogeneous, which was very similar to the distribution of the total haze daysand mainly concentrated in the northeastern Sichuan urban agglomeration, Chengdu Plain urban agglomeration and southern Sichuan urban agglomeration. The range of haze-prone areas increased in 1981~2010 and decreased significantly in 2011~2016. It is found that the Sichuan Basin is in the region of high (cold) high (low) pressure when more (less) years (periods) of continuous haze events occur. The Ural blocking high is weak (strong), the Siberian high is weak (strong), the trough in East Asia is weak (strong), the basin is convergent (divergent) to a certain extent, exists (does not exist) an obvious inversion structure and the vertical upward motion is weak (strong), these conditions are conducive to the accumulation of pollutant particles in the shallow boundary layer (conducive to the diffusion of pollutants), resulting in the maintenance (dissipation) of haze events.