| 中国东部冷锋推进中的PM2.5三维结构变化特征 |
| 摘要点击 1862 全文点击 813 投稿时间：2021-03-12 修订日期：2021-06-08 |
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| 中文关键词 数值模拟 空气污染 边界层结构 气象要素 PM2.5三维结构 |
| 英文关键词 numerical simulation air pollution boundary layer structure meteorological elements three-dimensional structure of PM2.5 |
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| 中文摘要 |
| 利用观测资料和中尺度天气-化学模式（WRF-Chem）对一次冷锋南下天气过程导致的我国东部大范围空气污染开展研究，强调了冷锋过境前后的边界层结构及其对PM2.5三维结构和变化的影响.观测发现，地面重污染区域位于冷锋前部均压场或等压线稀疏区域，在冷锋由北向南快速移动过程中，途经各站点PM2.5浓度峰值伴随锋前而至.WRF-Chem模式可以较好地模拟中国东部地面和高空气象要素以及PM2.5浓度的时空变化.模拟结果表明，处于该移动冷锋天气系统相同位置的沿途各站点的边界层结构以及PM2.5垂直廓线表现出相似的特征.即：当冷锋开始入侵时，锋前污染物从地面被抬升到高空，PM2.5浓度的增加和高空风速的增大导致高空PM2.5通量增大，且PM2.5浓度高值区随着高度升高向暖气团一侧倾斜.夜间冷锋过境引发边界层内对流性不稳定增加，边界层高度可达1 km以上，打破了边界层昼夜演变特征.本研究表明，垂直观测和精细模拟的结合可以有效地解释天气过程对空气污染的输送、分布和演变的影响，并为区域空气污染归因和治理提供精确指导. |
| 英文摘要 |
| Based on observational data and the WRF-Chem model, this study analyzed the large-scale air pollution in eastern China, which was caused by the weather process of a cold front moving southward, emphasizing the vertical structure of the boundary layer and the influence on the three-dimensional structure of PM2.5. Our observations revealed that the heavy pollution near the surface was located at sparse or equal isobar in front of the cold front. During the process of the weather system moving in, the timing of the maximum PM2.5 concentration at each station from north to south was delayed. The results show that the WRF-Chem model can better capture the spatial and temporal variations of surface and upper air meteorological elements and PM2.5 concentrations over eastern China. The simulation results show that the boundary layer structure and the vertical profile of PM2.5 at the same location of the mobile weather system showed similar characteristics. When the invasion takes place in a cold front, the pollutants in front of the cold front are rapidly lifted from the ground to a high altitude. The growth in PM2.5 concentration and the increasing wind speed at high altitudes lead to the upward trend in PM2.5 flux. As the altitude increases, the high-value area of PM2.5 concentration tilts towards the warm air mass. The transit of the cold front at night led to more unstable convection within the boundary layer; the height of the boundary layer increased from north to south, reaching over 1 km, breaking the rules characteristic of the diurnal evolution of the boundary layer. The results indicate that the combination of vertical observations and elaborate simulation can effectively explain the impact of synoptic processes on the transport, distribution, and evolution of air pollution and provide precise pollution-control directives. |
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