利用星载和地基激光雷达分析2019年5月东亚沙尘天气过程

Analysis of a Dust Weather Process over East Asia in May 2019 Based on Satellite and Ground-Based Lidar

2019年5月中旬,中国北方出现大范围沙尘暴天气,此次天气过程持续时间较长,影响范围较大。利用星载激光雷达CALIOP(Cloud-Aerosol Lidar with Orthogonal Polarization)和地基激光雷达AD-NET(Asian Dust and aerosol lidar observation NETwork)数据,对此次沙尘天气过程中沙尘气溶胶的分布特征以及沙尘传输过程进行分析;利用国家气象信息中心提供的小时天气实况数据对星载激光雷达资料以及后向轨迹模型HYSPLIT(the HYbird Single Particle Lagrangian Integrated Trajectory)得到的传输路径进行验证,同时结合空气质量数据分析此次天气过程对空气质量的影响;利用欧洲中心ERA-Interim再分析资料对此次沙尘天气成因进行分析。结果表明:(1)2019年5月10~16日沙尘天气主要分为两阶段,第一阶段为5月10~12日,第二阶段为13~16日。(2)通过CALIOP垂直特征层产品,发现在太平洋地区5~10 km的较高高度上,存在沙尘气溶胶,到达日本地区时,沙尘气溶胶的退偏比和色比平均值分别为0.14和1.29。(3)经过星载和地基激光雷达数据的综合分析,发现5月13~18日期间,沙尘气溶胶对日本长崎站点和韩国济州岛地基激光雷达站点的平均贡献率均值分别为42.16%和39.25%。(4)筛选了星载激光雷达经过日本和韩国站点的轨迹,对比分析两种数据的衰减后向散射系数以及表观散射比,发现两种数据的表观散射比廓线分布具有相近的变化趋势。(5)在沙尘天气期间,颗粒物浓度显著增加,PM10浓度最大值超过1500μg m-3,是国家一级浓度标准的30倍;而5月11日PM2.5浓度在甘肃省最大,最大值达到国家一级浓度标准的7倍,14日最大值甚至达到12倍;PM10与PM2.5的浓度比值也在甘肃新疆多地达到6以上。(6)内蒙古西部的小槽的加深以及南压,使得西北冷空气稳定南下;在14日,不稳定层结加深导致沙尘天气再一次爆发。

In May 2019, a strong sandstorm occurred in northern China, which lasted for a relatively long time and impacted a large area. The optical properties, vertical distribution and the transmission of the dust aerosols are analyzed using the data from the Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP) and the ground-based lidar(Asian Dust and aerosol lidar observation NETwork, AD-NET). At the same time, the track of this dust process is validated by the hourly data from the China Meteorological Data Service Center and the HYbird Single Particle Lagrangian Integrated Trajectory(HYSPLIT) model. Combined with the air-quality data from the PRC State Environmental Protection Administration, the influence on air quality is also analyzed. In addition, the ERA-interim reanalysis data are used to analyze the causes of the dust weather. The results show that:(1) The sand-storm process can be mainly divided into two stages, with the first stage from May 10 th to 12 th and the second stage from 13 th to 16 th.(2) The dust aerosols exist at a high altitude of 5-10 km in the Pacific region, and the depolarization ratio and the color ratio of the dust are 0.14 and1.29, respectively.(3) After the comprehensive analysis of the data from the satellite and ground-based lidar, it is found that the dust is transmitted to Jeju in South Korea and Fukuoka in Japan, and the dust aerosols contribute to the station dust observations on average of 39.25% and 35.43%, respectively.(4) The trends of the attenuation backscattering coefficients and the apparent ratios from the ground-based AD-NET data and the corresponding CALIOP satellite-based lidar data are similar.(5) During the dust process, the concentration of particle matters increases significantly. The maximum concentration of PM10 surpasses 1500 μg m-3, which is about 30 times of the national first-level standard. On May 11 th and 14 th, the mean values of PM2.5 and PM10 are very high in Gansu Province, which reach 7 times and 12 times of the national first-level standard, respectively, while the ratio of PM10 and PM2.5 reaches above 6 at many places in Gansu Province and Xinjiang.(6) The low trough at the western Inner Mongolia deepens and extends to east, and the South Asia high moves steadily southward, which together bring the cold air southward. On May 14 th, the instability stratification is strengthened, which leads to the outbreak of the dust weather.