基于长时序“地-星”数据的京津冀大气污染时空分布及演变特征

Spatial-temporal Distribution and Evolution Characteristics of Air Pollution in Beijing-Tianjin-Hebei Region Based on Long-term“Ground-Satellite”Data

为了促进区域社会经济与生态环境协调发展,构建美好人居环境,精准防污治污,对大气污染有准确充分了解,开展对京津冀大气污染状况深度摸排和普查.基于2014~2019年6 a地面环境观测数据和2000~2019年卫星数据,分析大气污染在不同尺度时间和空间上的分布特征和演变态势.结果表明:(1)站点PM_(2.5)日均值浓度显示,京津冀污染呈现天数多、等级重和总体向好的特征.污染主要发生在10月到次年4月,占近半年时间.张家口PM_(2.5)表现最优,其次秦皇岛;(2)卫星近20年PM_(2.5)年平均浓度呈现出平原大于山区,城市大于郊区的空间分布特征.时间上呈现出四阶段双峰结构的“M”型演变特征,从2000年开始逐渐增加,2006年出现第一峰,2007年开始逐渐降低,直到2012年.2013年骤升为第二高峰,之后逐年降低,到2017年;(3)基于卫星每10 a的月平均AOT数据看月度变化特征,总体上,第一时间段(2000~2009年)的AOT月均值大于第二时间段(2010~2019年)同月,最大值在7月,最小值在12月.张家口和承德近20年月平均AOT变化微弱,平原地区季节差异和空间差异显著;(4)站点观测的O_(3)-8h日均值表明,京津冀O_(3)-8h浓度良好等级频发,出现时间广,3~10月.轻度污染等级至少出现7次,未出现中度及以上污染等级;(5)地面观测SO_(2)日均值表明,未出现轻度及以上等级污染,良好等级污染出现在冬季,且多以连续几日污染形式出现;(6)对AQI数据分析发现,2015~2019年,北京AQI优级占比从27%依次增加到38%,天津AQI良好等级占比依次从44%增加到64%.邯郸AQI优级占比最高出现在2016年,仅占9%;(7)基于卫星近20年的月平均SO_(2)数据表明,高值区出现在邯郸、邢台和石家庄,低值区在张家口和承德.20 a平均NO_(2)数据表明高值中心在北京、天津、唐山、邯郸、邢台和石家庄.

This study aimed to promote the coordinated development of regional social economy and ecological environment,build a better living environment,accurately prevent and control pollution,and carry out in-depth surveys and general surveys of air pollution in Beijing,Tianjin,and Hebei.Based on 6 years(June 2014 to December 2019)of ground environmental observation data and satellite data from 2000 to 2019,the distribution characteristics and evolution trend of air pollution in different time and spatial scales were analyzed.The results showed that:(1)according to the daily average concentration of PM_(2.5) at the sites,the pollution in the Beijing-Tianjin-Hebei region showed the characteristics of more days,heavy levels,and overall improvement.Pollution mainly occurred from October to April of the following year,accounting for nearly half a year.The pollution level of PM_(2.5) was the best at Zhangjiakou,followed by Qinhuangdao.(2)Based on the 20-year average PM_(2.5) annual average concentration data retrieved from satellites,the PM_(2.5) concentration presented a spatial distribution characteristic in which that in the plains was higher than that in mountain area,and PM_(2.5) concentration in the city was higher than that in the suburbs.PM_(2.5) concentration changed with time,showing a four-stage bimodal structure of"M"-type evolution characteristics,which gradually increased starting in 2000;the first peak appeared in 2006 and gradually decreased from 2007 to 2012.It rose sharply to the second peak in 2013 and then decreased yearly until 2017.(3)The monthly average AOT data based on satellites every 10 years indicated that the value of AOT in the first time period(2000-2009)was larger than that in the same month of the second time period(2010-2019).The maximum value was in July,and the minimum value was in December.The monthly average AOT in Zhangjiakou and Chengde changed slightly over the past 20 years,and the seasonal and spatial differences were significant in the plain area.(4)Judging from the daily average value of O_(3)-8 h observed at the stations,good levels of O_(3)-8 h concentrations in the Beijing-Tianjin-Hebei area occurred frequently and widely from March to October.There were at least seven instances of light pollution levels,and the moderate pollution levels and above were not observed.(5)The daily average value of SO_(2) observed on the ground showed that there was no light pollution or above;the good pollution level occurred in winter,and most appeared in the form of pollution for several consecutive days.(6)The analysis of AQI data revealed that from 2015 to 2019,the proportion of AQI excellent grades in Beijing increased from 27%to 38%,and the proportion of Tianjin AQI good grades increased from 44%to 64%.The highest proportion of Handan AQI superior grades appeared in 2016,accounting for only 9%.(7)The 20-year monthly average concentration of SO_(2) data based on satellites showed that high-value areas were in Handan,Xingtai,and Shijiazhuang,and low-value areas were in Zhangjiakou and Chengde.The 20-year average NO_(2) data showed that the high-value centers were in Beijing,Tianjin,Tangshan,Handan,Xingtai,and Shijiazhuang.