拉萨城区PM10和PM2.5多时间尺度特征及气象条件相关性研究

Multi-time Scale Characteristics of PM10 and PM2.5 and Their Correlation with Meteorological Conditions in Urban Lhasa

  • 摘要: 基于2018—2022年拉萨城区空气质量监测站PM2.5、PM10数据和国家级气象站观测数据,利用数理统计、相关性分析等方法,综合分析了城区PM2.5、PM10、PM2.5/PM10的多时间尺度变化特征及其与风速、相对湿度、降水的关系。结果表明:PM10和PM2.5年平均浓度均呈现显著的减小趋势(每年分别减少5.88 μg·m−3、1.57 μg·m−3);季节性变化表现为夏秋季低、冬春季高的特征,由大到小依次为冬季>春季>秋季>夏季;月变化表现为明显的U型分布,低值区出现在6—10月,高值区为11月—次年5月;日变化特征均表现为双峰双谷型,PM10和PM2.5峰谷值之比分别达到2.44、2.22,有着非常显著的峰谷变化特征。气象条件对颗粒物的浓度分布有着重要影响;其中,风速对PM2.5浓度分布表现为明显的负相关,而对PM10则表现为弱的负相关;相对湿度对PM10和PM2.5浓度分布均表现为显著的负相关,秋季相对湿度的影响在四季中最为显著;降水对PM10和PM2.5浓度分布均存在明显的负相关,其平均清除率分别为4.18%和3.11%。

     

    Abstract: Based on the data of PM2.5 and PM10 from air quality monitoring stations and national meteorological stations in Lhasa from 2018 to 2022, the multi-time scale variation characteristics of PM2.5, PM10 and PM2.5/PM10 and their relationships with wind speed, relative humidity and precipitation were comprehensively analyzed by means of mathematical statistics and correlation analysis methods. The results indicate that the average annual concentration of PM10 and PM2.5 showed a significant decreasing trend (5.88 μg·m−3/ year and 1.57 μg·m−3/ year, respectively). The seasonal changes were lower in summer and autumn, higher in winter and spring, with the order being winter > spring > autumn > summer. The monthly variation showed a significant U-shaped distribution, with the low value area appearing from June to October, and the high value area from November to May of the following year. The diurnal variation characteristics were characterized by double peaks and double valleys. The peak-to-trough ratios for PM10 and PM2.5 reached 2.44 and 2.22, respectively, with significant peak-valley variation characteristics. Meteorological conditions significantly influenced the concentration distribution of particulate matter. Among them, wind speed showed a strong negative correlation with PM2.5 concentration distribution, but a weak negative correlation with PM10. Relative humidity had a significant negative correlation with PM10 and PM2.5 concentration distribution, and the influence of relative humidity was most significant in autumn. Precipitation had a significant negative correlation with the concentration distribution of PM10 and PM2.5, and the average clearance rates were 4.18% and 3.11%, respectively.

     

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