| Autor: |
Wu J; Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei, Beijing 100089, China.; Shangdianzi National Atmosphere Background Station, Beijing 101507, China., Li C; Beijing Meteorological Service Center, Beijing 100089, China., Ma ZQ; Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei, Beijing 100089, China., Sun ZB; Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089, China., Han TT; Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei, Beijing 100089, China., Qiu YL; Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei, Beijing 100089, China., Ma XH; Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei, Beijing 100089, China., Li YR; Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei, Beijing 100089, China., Zhu XW; Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei, Beijing 100089, China. |
| Abstrakt: |
Under certain terrain and weather conditions, mountain-valley circulation is one of the main meteorological factors affecting aerosol pollution in plain-mountain area. Based on environmental monitoring data and multi-source meteorological data for the Beijing-Tianjin-Hebei region between 2015 and 2019, the characteristics, similarities, and differences of mountain-valley winds in the Beijing Plain and Yanhuai Basin regions were compared. The results show that the mountain-valley winds recorded at the Beijing Observatory are from southwest to northeast compared to from the southeast to northeast at Yanqing station. With the aggravation of pollution levels, the mountain-valley wind intensity decreased by 17.7%-32.4%. When the wind speed at Beijing Observatory was 2-6 m·s -1 , the maximum PM 2.5 concentration in southeast was 83 μg·m -3 , which was higher than in the southwest. When the wind speed at the Yanqing station was 2-6 m·s -1 , the PM 2.5 concentrations in SE-SSE area was 20-40 μg·m -3 higher than in other directions, and the concentrations in the valley winds were 10-12 μg·m -3 higher than the average value for the last five years. Taking the typical heavy pollution event on March 5-8, 2015, as an example, the influence of mountain-valley winds is mainly reflected in the high humidity and regional transmission of southeast winds during the valley wind stage. The PM 2.5 concentrations at the Yanqing station increased by 100-130 μg·m -3 during the valley wind stage on March 6 and 7, 2015. The inversion temperature developed to 1000 m during the mountain wind stage, the local dew point at the Beijing Observatory and the Yanqing station rose by approximately 18℃. The peak dew point at the Yanqing station occurring 2 hours after the Beijing Observatory, and the concentrations of PM 2.5 rose slightly under high humidity conditions. Meanwhile, the thermal gradient between the 400-m-high Yanqing Station and Yudu Mountain gradually decreased, and the mountain-valley wind decreased by 8% and 6%, respectively. The weakening of local circulation may be related to the bidirectional feedback mechanism of the boundary layer and high concentrations of aerosols. |
