| 城区与郊区PM2.5污染及传输特征差异性 |
| 摘要点击 2758 全文点击 2063 投稿时间：2022-01-22 修订日期：2022-03-23 |
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| 中文关键词 边界层高度 PM2.5 传输特征 城区 郊区 |
| 英文关键词 boundary layer height PM2.5 transport characteristics urban areas suburbs |
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| 中文摘要 |
| 基于云高仪激光雷达、飞机AMDAR数据和常规站点等多源观测数据，并与数值模拟（CAMx-PSAT模型）相结合，以京津冀典型城市——北京城区与郊区（密云）和石家庄城区与郊区（平山）为案例研究区域，对城区和郊区边界层高度差异（ΔPBLH）、地面PM2.5浓度差异（ΔSurf_PM2.5）、高空PM2.5浓度差异（ΔVert_PM2.5）和传输通量强度及高度分布特征差异进行分析.结果表明，由于人为热源、短波辐射和热力湍流等因素，导致城区年均边界层高度（PBLH）较郊区高8%~29%，且不同季节下城区PBLH月均较郊区高2%（石家庄4月）~47%（北京7月）.由于人为排放、逆温和大气湍流等共同作用，在0~1260 m之间等高度城区年均ρ（PM2.5）较郊区高0.1（石家庄）~29.7（北京）μg ·m-3，随高度增加而减小.城区年均总净通量强度远大于郊区，城区表现为流出，郊区表现为流入，是由于城区低压和郊区高压，形成城郊热力环流.北京城区和郊区与周边的年均总净通量强度之和（44.77 t ·d-1）大于石家庄（34.44 t ·d-1）.受风速和PM2.5浓度的影响，在0~1260 m之间，城区和郊区与周边的净通量随离地高度的增加通量强度呈现明显增大趋势，其中1月城区和4月郊区与周边的传输交换对环境影响最为明显.不同季节下城区和郊区最大净通量的强度差异明显，两者相差2.23~4.48倍；但最大净通量强度的高度特征差异较小，主要位于611~1260 m. |
| 英文摘要 |
| Based on multi-source observation data, such as lidar ceilometer, aircraft AMDAR, and conventional sites, combined with numerical simulation (CAMx-PSAT), this study took the typical cities of the Beijing-Tianjin-Hebei region-Beijing (BJ) urban area and suburbs (Miyun) and Shijiazhuang (SJZ) urban area and suburbs (Pingshan) as the case study areas. The differences in boundary layer height between urban areas and suburbs (ΔPBLH), surface PM2.5 mass concentration (ΔSurf_PM2.5), vertical PM2.5 mass concentration (ΔVert_PM2.5), and transmission flux intensity and height distribution characteristics were analyzed. The results showed:due to factors such as anthropogenic heat sources, short-wave radiation, and thermal turbulence, the annual average planetary boundary layer height in urban areas was 8%-29% higher than that in the suburbs, and in different seasons, the monthly average planetary boundary layer height in urban areas was 2% (April in SJZ)-47% (July in BJ) higher than that in the suburbs. Due to the combined effects of anthropogenic emissions, inversions, and atmospheric turbulence, the annual averageρ(PM2.5) in urban areas between 0-1260 m was higher than that in suburbs by 0.1 (SJZ)-29.7 (BJ) μg·m-3 and decreased with the increase in height. The annual average total net flux intensity in urban areas was much greater than that in suburbs, with outflows in urban areas and inflows in suburbs; due to the urban low pressure and the suburban high pressure, suburban thermal circulation was formed. The annual average total net flux intensity in BJ (44.77 t·d-1) was greater than that in SJZ (34.44 t·d-1). Affected by wind speed and PM2.5 mass concentration, between 0-1260 m, the fluxes in urban areas and suburbs and surrounding areas showed an obvious trend of increasing net flux intensity with the increase in height above the ground. Furthermore, the transmission exchange between urban areas and suburbs and surrounding areas in January and April had the most obvious impact on the environment. The intensity of the maximum net flux in the lower urban areas and the suburbs in different seasons was significantly different, and the difference between the two was 2.23-4.48 times; however, the height characteristic difference in the intensity of the maximum net flux was small, mainly located at 611-1260 m. |
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