卫星遥感反演京津冀地区2011—2017年氮氧化物污染变化

Satellite-based observations of changes in nitrogen oxides over the Beijing-Tianjin-Hebei region from 2011 to 2017

基于POMINO AMFv6反演构架和高分辨率WRF-CMAQ模拟资料重构DOMINO v2大气质量因子,开发了京津冀地区高精度NO_2对流层垂直柱浓度卫星数据,并结合反演模型分析了研究区域2011—2017年NO_2柱浓度及重点城市NO_x排放强度的时空演变.2011—2017年间,京津冀地区NO_2柱浓度在北京-天津-唐山及石家庄-邢台-邯郸形成两个核心污染高值区,保定、廊坊、秦皇岛、沧州和衡水分布于东南部的污染背景中,构成污染次高值区,而位于西北部的张家口和北部的承德相对较为清洁,仅在对应的市辖区出现局地污染峰值.京津冀地区柱浓度平均水平在2011—2017年间下降了27.2%.2011—2013年间北京、天津、唐山和石家庄市的NO_x平均排放强度分别为108.3、139.5、241.4和178.6mol·s^(-1),而2015—2017年间下降至98.0、108.2、197.6和85.8 mol·s^(-1).基于卫星遥感手段的综合分析表明,2011—2017年期间京津冀地区NO_x污染状况得到明显改善,但各个城市的改善程度存在差异,其中北京、唐山NO_2柱浓度降幅明显低于污染核心高值区的其他城市,在下一阶段制订治理方案时应重点考虑.

Nitrogen oxides play key roles in tropospheric chemistry and have adverse effects on human health. In this work,we develop an improved product of NO2 tropospheric vertical column densities（ TVCDs） over the Beijing-Tianjin-Hebei（ BTH） region based on the operational OMI NO2 product from KNMI. In the improved product,air mass factors for converting slant columns to vertical columns are calculated using simulated NO2 profile,pressure,temperature and relative humidity at a horizon resolution of 4 km×4 km. The product is then used to reveal the spatiotemporal variation of NO2 TVCDs over the BTH region,and is fitted with a parameterized two-dimensional gaussian function to assess NOx emission changes over BTH region. Two hotspots of NO2 pollutions are observed over two city clusters,Beijing-tianjin-tangshan and Shijiazhuang-xingtai-handan. Elevated NO2 TVCDs are also observed over the Baoding,Langfang,Qinhuangdao,Cangzhou and Hengshui city. Averaged NO2 TVCD over the BTH region decreased by 27.2% from2011 to 2017. The fitted NOx emission rates over the Beijing,Tianjin,Tangshan and Shijiazhuang city decreased from 108. 3,139. 5,241. 4,178. 6 mol·s-1 during 2011—2013,respectively,to 98.0,108.2,197. 6,85. 8 mol·s-1 during 2015—2017. Reduction rates of NO2 TVCDs in Beijing and Tangshan city are lower than other cities during 2011—2017,indicating that stricter controls are required in the future.