Fog-Haze Connecting Factors Analysis Over The Beijing Region And Advance Of The Standard

With the rapid development of urbanization and industrialization of Beijing and other modernization cities, the industry and transportation network of developed area emission more and more contaminants to atmosphere, which caused the poor visibility of atmosphere and more haze days. This situation causes bad effect on people s production and life. So, analyzing the atmospheric visibility impact factor and the fog-haze weather impact factor of Beijing more detaily and formulating a regional applicable fog-haze distinction method is very important to improve the air quality, haze weather warning and formulate the fog-haze distinction standard.We analyzed the temporal and spatial distribution of haze days in Beijing region in 2014 by using 18 meteorological observation data with different typical fog-haze discriminant methods.By using Shunxi station as an example, this article studied the atmospheric visibility and its impact factor of Shun Yi. Combine with the severe haze weather of Beijing in November 19 to 21, we analyzed the pollution process and the variation of meteorological conditions in the corresponding process. We analyzed the haze weather characteristics of three typical stations to improve the existing fog-haze distinction standard by using part of PM2.5 effective observation data and the meteorological data in the corresponding period of 14 stations of the three major economic zones in 2013.The results show that:Through method 1 (average daily visibility<10km, the average daily relative humidity <90%, it is determined haze days), we can achieve the most haze days of Beijing in 2014. The statistical results is similar to the Standard.The haze spatial distribution of Beijing overall shows a decreasing trend from south to north. In the densely and urbanization region, such as, Beijing, Zhaoyang, Fangshan, the cumulative annual haze days is 90d at least. The temporal distribution characteristics of haze in Beijing is different in different seasons which is ranking as: winter>spring>summer>autumn.When excluding the fog data of Beijing in 2014 according to the existing discrimination methods, the revised extinction coefficient still has much difference in autumn and winter. The dry extinction coefficient daily variation of Beijing is similar in winter and autumn, so does in spring and summer. Compared to afternoon, the dry extinction coefficient in spring and summer is larger in the morning; In autumn and winter, the dry extinction coefficient is larger in the morning and evening than the afternoon. The dry extinction coefficient seasonal variation is in the same growing trend with haze days and the relativity reaches to 0.89. During the observation period in 2014,46.27% of the days are in the haze pollution state. When the PM2.5 mass concentration is larger than 200μg·m-3, the probability occurrence of haze is 100%. The visibility decay exponentially with the increase of PM2.5 mass concentration with the relativity reach to 0.71.When the visibility is 10km, the PM2.5mass concentration is 57.8μg·m-3.The result predicted by multiple linear regression equation has the same trend with the observation data of visibility. The factors which influence visibility have different weights in different relative humidity range. The higher pollutant emission and the unfavorable meteorological conditions are the internal and external causes of explosive heavy haze pollution. Building and lay of land are assistant factors.Beijing is frequently in the cases of PM2.5 overproof at low humidity and fog-haze mixture in high wet. Hangzhou and Guangzhou is frequently in the cases of fog-haze mixture in high wet and fog. Beijing which represents for Beijing-Tianjin-Hebei region has more severe haze situation than Guangzhou which represents for the pearl river delta area. Hangzhou has more mild or moderate haze days with visibility less than 5km; Guangzhou can appears high、middle and low visibility haze days; Beijing fog-haze visibility is more concentrated in more than 10km and less than 6km. PM2.5 fine particles show different sensitivity to atmospheric extinction under the different relative humidity classification in different region. We revised the existing standard considering the existing observation level and the air quality standards proposed by the environmental protection department. The new standard improve the existing standard and reset the threshold of discriminant factor of PM2.5、relative humidity and visibility to 35μg·m-3 90% and 7.5km, respectively. As a result, the improved standard can distinguish the fog-haze mixed condition of original standard better and can completely identify the events at low visibility condition. The improved method is more suitable for the cities which have more fog-haze mixed weather. Compared to the existing standard, the results of the improved method have the same variation trend.