Analysis on the Change Characteristics of Haze in Dezhou City in Recent 40 Years

[Objective] The aim was to analyze the change characteristics of haze in Dezhou City. [Method] Based on the data of haze and sunshine duration from 11 counties or cities in Dezhou City from 1970 to 2009, the daily, monthly, seasonal and annual variation of haze and their variation reasons were studied, meanwhile, the effects of haze on sunshine duration were discussed. [Result] Haze occurred most frequently from 09:00 to 14:00 and daily variation was different in various seasons; haze days were the most in December (200 d), and next came January (161 d), while hazes days were the fewest in August (20 d). From seasonal variation, haze appeared most frequently in winter, accounting for 40% of that in total year, autumn (23%) and summer (20%) the second, and haze days were the fewest in spring (18%). For annual variation, haze days were the fewest from 1970 to 1979 (110 d) and most from 2000 to 2009 (724 d), with the tendency rate of 2.27 and 16.35 d/a, respectively. From regional distribution, haze days were the most in Decheng District, and next came Xiajin, while Yucheng had the fewest haze days. In addition, the annual variation of haze days was related to pollutant concentration in atmosphere, while monthly variation and seasonal variation were controlled by weather situation and meteorological condition. [Conclusion] The study could provide scientific reference for the prevention and impact assessment of haze.

德州及周边5市大气污染扩散条件评估

应用EC细网格再分析资料(ERA5)和地面观测资料,分析了德州及周边5市2000—2017年秋季、冬季和春季(9月—次年5月)的小风日数、10 m风速、混合层平均风速、混合层高度、通风量和大气自净能力等6个静稳天气指数的变化特征,对大气污染扩散条件进行评估。结果表明:(1)德州、聊城、济南、滨州小风日数逐年波动增加,2007年和2011年增加明显,其中德州增加趋势最大,平均每年增加12.3 d;其他5个指数呈逐年波动减小,最小值出现在2016年或2017年;各市大气自净能力分别在2011年和2016年出现明显下降。(2)小风日数呈逐月波动减少变化,9月最多,3月或4月最少;其他5个指数为逐月波动增加变化,最大值出现在3月或4月,其中冬季1月小风日数最多,10 m风速小,通风量小,大气自净能力最差。(3)对6市静稳天气指数分析表明,各市大气污染扩散条件都在变差,其中德州变化最快;大气污染扩散条件由好到差排序为济南、沧州、德州、滨州、衡水、聊城。