珠江三角洲典型灰霾过程的边界层特征

2014年1月初珠江三角洲(以下简称珠三角)地区出现严重的灰霾天气.利用广东省城市空气质量资料、中国气象局番禺大气成分站逐时PM10、PM2.5、PM1以及能见度数据、广东省946个自动站风向风速数据、广州基本站风向风速数据、2013~2014年东莞佛山大气边界层观测试验资料等,研究了珠三角2014年1月1~8日典型灰霾过程的边界层特征.结果表明:大陆冷高压变性出海是这次灰霾过程发生的主要天气系统.其使得珠三角地区受静稳天气控制,造成微风或静风状况以及低的边界层和逆温结构;6日珠三角主要城市空气质量呈现不同的变化,其原因主要是区域内风向的变化,5日上午珠三角为弱的偏北风,整个珠三角都为灰霾天气,而5日下午风向由偏北风转为偏南风,珠三角东南部地区空气质量改善,北部(内陆)地区的空气质量恶化;后向轨迹分析发现所有气流呈明显下沉作用,且5日20:00的后向轨迹簇来自陆面,6日20:00的后向轨迹簇来自海面,两者对珠三角的空气质量具有不同的影响.

Boundary layer characteristics of typical haze process in the Pearl River Delta region

A heavy haze weather occurred in Pearl River Delta (PRD) region during January 2014. Based on urban air quality data of Guangdong Province, hourly data of PM10, PM2.5 and visibility from China Meteorological Agency Panyu atmospheric composition station, wind data of 946 auto stations and Guangzhou station, data from the boundary layer observation experiment in Dongguan and Foshan during the winter of 2013, boundary layer characteristics of a typical haze process in PRD during 1~8 January 2014 had been researched. It was found that, continental cold high was the major weather system at this haze process. It caused stability weather which produced breeze or calm wind condition, lower boundary layer and inversion structure occurred in PRD. Air quality of major cities in PRD had different variations during 6th January, mainly due to the change in wind direction over the Pearl River Delta region. In the morning of 5th January, the Pearl River Delta region was prevailing with weak northerly winds, it caused the entire Pearl River Delta suffer with haze weather. While on the afternoon, the wind direction had been changed that the northerly winds turned to southerly winds, it improved the air quality over the southeastern Pearl River Delta region. However, air quality of the northern (inland) region deteriorated. Backward trajectory analysis found that all airflow with obviously sinking process, and the trajectory clusters that began at 20:00 5th January were come from the land surface, while the trajectory clusters that began at 20:00 6th January were come from the sea. These two kinds of trajectory clusters have different effects on air quality in the Pearl River Delta.