Dong Qun, Zhao Pu-Sheng, Wang Ying-Chun, Miao Shi-Guang, Gao Jian
Chinese Academy of Meteorological Sciences, Beijing 100081, China.
Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089, China.
Huan Jing Ke Xue. 2017 Jun 8;38(6):2218-2230. doi: 10.13227/j.hjkx.201609231.
The impact of mountain-valley wind circulation on the typical examples of pollution was analyzed through the selected pollution process, combining with the hourly PM concentrations and meteorological data in Haidian, Shangdianzi and Lishuiqiao in Autumn and Winter from 2013 to 2015, and also the data of Tower of atmospheric, wind profile of Haidian and automatic meteorological stations in the same period. The analysis showed that the average wind speed of valley wind was greater than that of the mountain wind, and they both would be "broken" during the conversion time in the mountain-valley wind days. In contrast with the mountain wind, the average duration of valley wind in autumn was longer than that in winter, and the start time of valley wind in autumn was earlier than the same wind in winter; influenced by the topography of Beijing area, the direction boundary of the transformation between mountain-valley wind was northeast-southwest. The frontier of mountain wind in autumn could fall down to the South Second Ring Road, and it could be pressed to the South Third Ring Road in winter; the average thickness of valley wind was greater than the mountain wind. Whether the moment was in autumn or winter, in the south, the average time when the PM concentration began to rise, was earlier than in the north in a day; the time when concentration of pollutants began to rise in the fall was earlier than in the winter, but the time when the concentration began to decline showed the opposite trend. The transition zone of different PM concentration in Beijing in autumn or winter located in South Second Ring Road (South Third Ring Road), and it would move to south over time. Duration autumn and winter seasons, this phenomenon lasted about 4 and 2 hours, respectively. Furthermore, the positive and negative feedback effects may exist between pollutant concentrations and mountain-valley wind.
通过选取污染过程，结合2013年至2015年秋冬季节海淀、上甸子和丽水桥的逐小时PM浓度及气象数据，以及同期的大气铁塔数据、海淀风廓线和自动气象站数据，分析了山谷风环流对典型污染事例的影响。分析表明，谷风的平均风速大于山风，在山谷风日的转换时刻二者均会出现“中断”。与山风相比，秋季谷风的平均持续时间长于冬季，且秋季谷风的起始时间早于冬季；受北京地区地形影响，山谷风转换的方向边界为东北-西南向。秋季山风前沿可下探至南二环路，冬季可被挤压至南三环路；谷风的平均厚度大于山风。无论秋季还是冬季，一天中南部PM浓度开始升高的平均时间早于北部；秋季污染物浓度开始升高的时间早于冬季，但浓度开始下降的时间则相反。北京秋冬季节不同PM浓度的过渡区位于南二环路（南三环路），且会随时间向南移动。秋冬季节，该现象分别持续约4小时和2小时。此外，污染物浓度与山谷风之间可能存在正负反馈效应。
