基于激光雷达数据对混合层高度与细颗粒物浓度关系的研究

Research on Relations between Atmospheric Mixing Layer Heights and Fine Particle Concentrations with Lidar Measurements

利用微脉冲激光雷达观测资料,运用人工辅助算法,获得2016―2019年白天混合层高度(MLH),并分析其变化特征及其与空气污染物PM_(2.5)浓度的关系。结果表明,混合层高度表现出明显的季节变化和日变化,春季高度明显大于其他季节,最大值均发生在5月。混合层高度在08:00―15:00 BJT的变化趋势与PM_(2.5)浓度负相关。线性拟合结果表明,当考虑风速的影响时,通风指数与PM_(2.5)具有更强的负相关关系;当考虑风向的影响时,西南风情况下,混合层高度与PM_(2.5)具有更强的负相关关系。对天气分型后,每个天气类型的PM_(2.5)浓度与混合层高度的相关性更加显著。

Based on the observations of a micro-pulse lidar in Beijing,the MLH is retrieved by using the artificial assistance algorithm during the day from 2016 to 2019.Then the seasonal and diurnal variations of MLH and its relationship with PM_(2.5) mass concentration are analyzed.The results show that the MLH shows obvious seasonal and diurnal changes,and the daily averaged MLH is significantly higher in spring than that in other seasons.The daily maximum MLH height in every year occurs in May of the year.The variation trend of the MLH is opposite to the concentration of PM_(2.5) from 08:00 am to 03:00 pm.Through linear fitting of the data,it is shown that the negative correlation is stronger when the ventilation index and wind speed are induced.When considering the influence of wind direction,the MLH has a stronger negative correlation with PM_(2.5) in the case of southwesterly wind.In addition,after weather classification,the correlation between PM_(2.5) and the MLH in each same weather group can be significantly improved.