关键词: 大气颗粒物, 垂直分布, 气象因子, 相关分析

Abstract:

Based on the observed PM_2.5, PM₁₀, TSP concentrations and meteorological factors including wind speed, air temperature, relative humidity at 1.5 m, 15 m, and 90 m heights from October 1, 2018, to September 30, 2019, in Shenyang, the vertical variation characteristics of atmospheric particulate concentration (APC) at different heights and their relationships with meteorological factors were analyzed.The results indicated that concentrations of different atmospheric particulates experience seasonal variations at different heights.The autumn and winter APCs are higher than those in spring and summer.The values of winter PM_2.5 concentration at 1.5 m, 15 m, and 90 m heights are in turn 54.98±12.67 μg·m^-3, 63.77±15.1 μg·m^-3, 39.27±5.62 μg·m^-3, i.e., the value at 15 m is greater than those at 1.5 m and 90 m, the corresponding values in autumn, spring and summer are in order of 1.5 m, 15 m, 90 m, the value at 1.5 m≈that at 15 m while the value at 15 m>that at 90 m, i.e.value (15 m) > value (90 m) > value (1.5 m), respectively.The diurnal variations of PM_2.5, PM₁₀, TSP concentrations are in the significant bimodal patterns in autumn and winter and unimodal patterns in spring at the three vertical heights, while the variations are in a unimodal pattern at 15 m height and have no obvious patterns at the other heights in summer.The variations of monthly mean APC show a significant difference between winter and summer seasons.Also, the concentrations of different sizes of atmospheric particulates vary with heights.In winter half-year, the monthly mean PM_2.5, PM₁₀, TSP concentrations at 1.5 m height and PM_2.5 concentration at 90 m height indicate the change characteristics of increase-decrease-increase-decrease, while the monthly mean PM_2.5, PM₁₀, TSP concentrations at 15 m height and PM₁₀, TSP concentrations at 90 m height tend to increase first and then decrease.The maximum values of APC in winter and summer half years occurred in January at 15 m height and June at three heights, respectively.The APCs at the two lower heights are higher than those at 90 m height in the winter half-year.In the summer half-year, the APCs among three heights have little difference and are much less than those in the winter half-year.The daily mean PM_2.5, PM₁₀, TSP concentrations are negatively correlated with wind speed and air temperature, and the correlation coefficients increase with the increase of the height and decrease with increase of the particle size.The relationships between daily mean PM_2.5, PM₁₀, TSP concentrations, and relative humidity are relatively complex, and the correlation coefficients vary with increase of the vertical height and particular size.

Key words: Atmospheric particulate, Vertical distribution, Meteorological factor, Correlation analysis