结合激光雷达分析2022年春季青海东部地区连续两次沙尘污染过程

Analysis of Two Sand-dust Pollution Processes in Qinghai Province in Spring 2022 by LIDAR

文章基于大气颗粒物监测激光雷达退偏振比实时数据以及PM_(10)、PM_(2.5)浓度小时数据对青海省2022年3月17至18日两次沙尘天气进行分析,结果表明,在沙尘影响期间PM_(10)浓度在短时间内呈爆发性增长,环青海湖地区的共和县PM_(10)浓度峰值远高于其他市(县),达到了4249μg/m^(3),是空气质量二级标准限值的28倍。从持续时间来看,各市(县)持续时间均在2~3 h,污染高值时段主要集中在3月17日傍晚到夜间。激光雷达监测结果表明,沙尘影响时段内,西宁市202.5 m处退偏振比高于502.5 m处,并呈现出明显的粗粒子污染特征。大气相对清洁时段,202.5 m和502.5 m高度退偏振比基本在0.1和0.05以下。3月17日18时,202.5 m和502.5 m处退偏振比为大气清洁时段的1.5倍和3倍。3月18日15时,202.5 m和502.5 m处退偏振比为大气清洁时段的1.5倍和2.8倍。沙尘因粗粒子增多使得退偏振比在短时间内增大。从轨迹分析看,西宁地区的气团源自偏西方不同高度层。

Based on the real-time data of the linear depolarization ratio of atmospheric particulate matter monitoring LIDAR and the hourly concentration data of PM_(10)and PM_(2.5),the atmospheric pollution caused by the impact of two sand and dust weather in Qinghai Province from March 17 to 18,2022 was analyzed.The results showed that during the period of dust impact,the concentration of PM_(10)increased explosively in a short period of time,and the peak concentration of PM_(10)in Gonghe County around Qinghai Lake was much higher than that in other cities(counties),reaching 4249μg/m3,which is 28 times the limit value of the secondary standard for air quality.From the perspective of duration,the duration of each city(county)is 2-3 hours,and the high value period of pollution is mainly concentrated from the evening to the night of March 17.The lidar monitoring results show that during the period of dust impact,the depolarization ratio at 202.5 m in Xining is higher than 502.5 m,and there are obvious characteristics of coarse particle pollution.During relatively clean atmospheric periods,the depolarization ratios at altitudes of 202.5 m and 502.5 m are basically below 0.1 and 0.05.At 18:00 on March 17,the depolarization ratio at 202.5 m and 502.5 m were 1.5 and 3 times higher than during the atmospheric cleaning period.At 15:00 on March 18 th,the depolarization ratio at 202.5 m and 502.5 m were 1.5 and 2.8 times higher than during the atmospheric cleaning period.The depolarization ratio of coarse particles increases in a short time due to sand dust.From the trajectory analysis,the air masses in Xining area originate from different levels to the west.