Modeling the impact of COVID-19 on air quality in southern California: implications for future control policies
Modeling the impact of COVID-19 on air quality in southern California: implications for future control policies
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DOI：
10.5194/acp-21-8693-2021
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发表时间：
2021-06-09
影响因子：
6.3
通讯作者：
Liou, Kuo-Nan
中科院分区：
文献类型：
--
作者：
Jiang, Zhe;Shi, Hongrong;Liou, Kuo-Nan
为应对2019年冠状病毒病(新冠肺炎)，加利福尼亚州在全州范围内发布全州居家命令，带来空气污染物排放的骤然大幅减少。这场危机为我们提供了一个前所未有的机会，可以从空气质量的角度评估减排的效果。在这里，我们使用化学天气研究和预测模式(WRF-CHEM)并结合地面观测来研究新冠肺炎封锁措施对南加州空气质量的影响。根据活动水平统计数据和卫星观测，我们估计了封锁期间部门排放的变化。由于排放量的减少，南加州的细颗粒物(PM2.5)的人口加权浓度下降了15%。在封禁前后PM2.5浓度下降中，减排贡献了68%，气象变化贡献了剩余的32%。在所有化学成分中，减排导致的PM2.5浓度下降的主要成分是硝酸盐和主要组分。对于O-3浓度，减排导致农村地区减少，但城市地区增加；人为挥发性有机化合物(VOCs)排放量减少70%可以抵消这一增加。这些发现表明，需要加强对初级PM2.5排放的控制，以及对氮氧化物和VOC排放的良好平衡控制，以有效和可持续地缓解南加州PM2.5和O-3污染。
In response to the coronavirus disease of 2019 (COVID-19), California issued statewide stay-at-home orders, bringing about abrupt and dramatic reductions in air pollutant emissions. This crisis offers us an unprecedented opportunity to evaluate the effectiveness of emission reductions in terms of air quality. Here we use the Weather Research and Forecasting model with Chemistry (WRF-Chem) in combination with surface observations to study the impact of the COVID-19 lockdown measures on air quality in southern California. Based on activity level statistics and satellite observations, we estimate the sectoral emission changes during the lockdown. Due to the reduced emissions, the population-weighted concentrations of fine particulate matter (PM2.5) decrease by 15% in southern California. The emission reductions contribute 68% of the PM2.5 concentration decrease before and after the lockdown, while meteorology variations contribute the remaining 32 %. Among all chemical compositions, the PM2.5 concentration decrease due to emission reductions is dominated by nitrate and primary components. For O-3 concentrations, the emission reductions cause a decrease in rural areas but an increase in urban areas; the increase can be offset by a 70% emission reduction in anthropogenic volatile organic compounds (VOCs). These findings suggest that a strengthened control on primary PM2.5 emissions and a well-balanced control on nitrogen oxides and VOC emissions are needed to effectively and sustainably alleviate PM2.5 and O-3 pollution in southern California.