基于后向轨迹的秋冬季漯河重污染输送及典型个例分析

利用常规气象数据、颗粒物观测数据、全球大气同化系统GDAS数据、NCEP再分析资料、ERA5再分析资料等,结合数理统计、轨迹聚类、天气学分析等方法对2015—2019年秋冬季漯河重污染特征、污染输送及潜在源区分布进行分析,并通过一次典型重污染个例进行证明。结果表明:近5 a秋冬季漯河重污染过程发生频次高、持续时间长、污染程度重,AQI、PM_(2.5)变化趋势不明显,PM_(10)浓度下降趋势明显,PM_(2.5)/PM_(10)比值逐年递增,以PM_(2.5)重污染为主。秋冬季漯河主要有6种气团输送路径,东北路、偏东路轨迹短、移速慢且高度低,近距离近地层污染输送特征明显,为重要重污染通道;西北路远距离下沉沉降输送和西南轨迹近距离输送下的AQI均值及重污染概率较低,对漯河重污染贡献不高。漯河潜在源区来源复杂、范围广、强度大,其污染潜在源主要分布在河南中东部、尤其是东北部,对应东北路径、偏东路径等气团轨迹。重污染时地面偏北风是其主导风,尤其是2—4 m·s^(-1)之间偏北到东北风最为显著。两次跨区域输送表明,北路或东北路近地层输送是AQI峰值维持发展的重要原因。

Transport and case study of heavy air pollution in Luohe during autumn and winter using backward trajectory analysis

Based on conventional meteorological data, particulate matter observation data, global atmospheric assimilation system(GDAS) data, and reanalysis data from the National Center for Environment Prediction(NCEP) and ERA5, we analyzed the characteristics, pollutant transport, and potential source areas of heavy air pollution in Luohe during autumn and winter from 2015 to 2019, using methods of mathematical statistics, trajectory cluster analysis, and synoptic analysis.We also conducted an evaluation using a typical heavy pollution event.The results showed that heavy air pollution events have exhibited high occurrence frequency, long duration, and heavy pollution intensity in Luohe during autumn and winter in the past 5 years.The variation trends of air quality index(AQI) and PM_2.5 are not obvious, while the PM₁₀ concentration reduces significantly.Meanwhile, the ratio of PM_2.5/PM₁₀ increases year by year, and PM_2.5 is the primary air pollutant in Luohe.There are six air mass transport paths in Luohe during autumn and winter.The northeast path and the east path are major transport channels for heavy air pollution, characterized by short trajectory, slow movement, low height, and obvious transport in the near-surface layer.The northwest path with long-distance transport and deposition and the southwest path with short-distance transport contribute less to heavy air pollution in Luohe, with a low AQI and low probability for heavy pollution on average.The potential sources of air pollutants in Luohe are complex, with a wide range and strong intensity.They are mainly distributed in the middle and eastern regions of He'nan province, especially in the northeast region, corresponding to air mass trajectories such as the northeast path and the east path.Northerly winds prevail near the surface during heavy air pollution events, especially for the northerly and northeasterly flows with speeds between 2-4 m·s^-1.Two regional transport events indicate that the near-surface transport along the north or northeast paths is the main reason for the maintenance and development of AQI peaks.