一次热带气旋外围下沉气流造成的珠三角地区连续灰霾天气过程分析

Analysis of a Haze Process Caused by Peripheral Subsidence of Tropical Cyclones over the Pearl River Delta Region

通过研究广州番禺大气成分站的气溶胶颗粒物质量浓度(PM_(10)和PM_(2.5))、黑碳浓度、臭氧浓度等大气成分要素,常规地面气象要素以及气流后向轨迹、垂直速度、位温和边界层高度等资料,结合热带气旋路径和天气形势对热带气旋外围下沉气流造成的一次珠三角地区连续灰霾天气过程的形成原因和变化特征进行了分析。由于热带气旋移动缓慢,其外围下沉气流使珠三角地区形成了层结稳定、静小风和晴朗少云的天气条件,导致珠三角地区出现连续的灰霾天气。在这次灰覆过程中,气溶胶粒子来源以本地源为主,并且以细粒子为主,PM_(2.5)占PM_(10)的比例接近70%,黑碳浓度占PM_(10)的6.0%左右;在凌晨,由于边界层高度降至最低,垂直扩散条件差,同时相对湿度也达到峰值,气溶胶吸湿增长明显,易出现能见度低值。

A study is made by using the data obtained from Panyu Atmospheric Composition Station, Guangzhou, including aerosol particle mass concentration （PM10, PM2.5）, black carbon concentration, o- zone concentration, surface meteorological data, backward trajectories, vertical velocity, potential temper- ature and boundary layer. In this study, the causes of a haze process caused by peripheral subsidence of tropical cyclones over the Pearl River Delta region is analyzed. The results show that the peripheral subsid- ence of tropical cyclones make a stable meteorological condition for this haze process, in which the aerosol particles are mainly from local sources. The PM2.5 and PM10 account for nearly 70% while black carbon and PM10 is nearly 6.0 %. The visibility is low in the morning because of the lowest boundary layer and highest relative humidity during a day.