摘要
2020年初新冠肺炎疫情(COVID-19)暴发后,中国多地实施了严格的管控措施,导致污染物排放量明显下降.但在减排实施的情况下,京津冀PM_(2.5)等污染物浓度较过去5 a同期却明显增长,出现了两次PM_(2.5)重度污染事件.利用欧洲中心ERA5再分析资料分析发现,相对于过去5 a,COVID-19管控期间京津冀地区的气象场表现为偏高的相对湿度、偏低的边界层高度和边界层内异常的辐合上升运动,有利于颗粒物的吸湿增长和二次转化,不利于污染物垂直方向上的扩散.此外,利用WRF-Chem模式开展敏感性试验发现,在京津冀中部地区气象场的变化导致2020年管控期间ρ(PM_(2.5))升高了20~55μg·m^(-3),升高比例高达60%~170%.进一步利用过程诊断分析法得出,增强的气溶胶化学过程和不利的湍流扩散条件是2020年COVID-19管控期间PM_(2.5)浓度升高的主要原因.在当今减排的大背景下,边界层高度和相对湿度的变化可能成为预报预测京津冀地区PM_(2.5)污染事件的重要指标.
The Chinese government triggered the immediate implementation of a lockdown policy in China following the outbreak of the COVID-19 pandemic,leading to drastic decreases in air pollutant emissions.However,concentrations of PM_(2.5)and other pollutants increased during the COVID-19 lockdown over the Jing-Jin-Ji region compared with those averaged over 2015-2019,and two PM_(2.5)pollution events occurred during the lockdown.Using the ERA5 reanalysis data,we found that the Jing-Jin-Ji region during the COVID-19 lockdown was characterized by higher relative humidity,lower planetary boundary layer height,and anomalous updraft.These conditions were favorable for condensation and the secondary formation of aerosols and prevented turbulent diffusion of pollutants.Furthermore,we conducted sensitivity tests using the WRF-Chem model and found thatρ(PM_(2.5))increased by 20-55μg·m^(-3)(60%-170%)over the middle region of Jing-Jin-Ji during the COVID-19 lockdown due to changes in meteorological conditions.Furthermore,the enhanced aerosol chemistry and unfavorable diffusion conditions were identified as the key factors driving increases in PM_(2.5)concentrations during the lockdown.Planetary boundary layer height and relative humidity may become the important factors in forecasting PM_(2.5)pollution events over the Jing-Jin-Ji region under the background of emission reduction.
作者
邱雨露
陈磊
朱佳
马志强
李梓铭
郭恒
唐颖潇
QIU Yu-lu;CHEN Lei;ZHU Jia;MA Zhi-qiang;LI Zi-ming;GUO Heng;TANG Ying-xiao(Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei,Beijing 100089,China;Collaborative Innovation Center of Atmospheric Environment and Equipment Technology,Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control(AEMPC),School of Environmental Science and Engineering,Nanjing University of Information Science&Technology,Nanjing 210044,China;Institute of Urban Meteorology,China Meteorological Administration,Beijing 100089,China;Tianjin Environmental Meteorology Center,Tianjin 300074,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2022年第6期2831-2839,共9页
Environmental Science
基金
北京市气象局科技项目(BMBKJ202001010)
江苏省大气环境监测与污染控制高技术研究重点实验室开放基金项目(KHK1902)
中国气象局气象软科学项目(2021ZZXM46)
国家自然科学基金项目(42007195)。
