Goldberg Daniel L, Anenberg Susan C, Griffin Debora, McLinden Chris A, Lu Zifeng, Streets David G
Department of Environmental and Occupational Health George Washington University Washington DC USA.
Energy Systems Division Argonne National Laboratory Lemont IL USA.
Geophys Res Lett. 2020 Sep 16;47(17):e2020GL089269. doi: 10.1029/2020GL089269. Epub 2020 Sep 5.
TROPOMI satellite data show substantial drops in nitrogen dioxide (NO) during COVID-19 physical distancing. To attribute NO changes to NO emissions changes over short timescales, one must account for meteorology. We find that meteorological patterns were especially favorable for low NO in much of the United States in spring 2020, complicating comparisons with spring 2019. Meteorological variations between years can cause column NO differences of ~15% over monthly timescales. After accounting for solar angle and meteorological considerations, we calculate that NO drops ranged between 9.2% and 43.4% among 20 cities in North America, with a median of 21.6%. Of the studied cities, largest NO drops (>30%) were in San Jose, Los Angeles, and Toronto, and smallest drops (<12%) were in Miami, Minneapolis, and Dallas. These normalized NO changes can be used to highlight locations with greater activity changes and better understand the sources contributing to adverse air quality in each city.
TROPOMI卫星数据显示，在新冠疫情实施物理隔离期间，二氧化氮（NO）大幅下降。要在短时间尺度上将NO的变化归因于NO排放的变化，必须考虑气象因素。我们发现，气象模式在2020年春季对美国大部分地区的低NO水平特别有利，这使得与2019年春季的比较变得复杂。年份之间的气象变化在月度时间尺度上可导致柱NO差异约15%。在考虑太阳角度和气象因素后，我们计算出北美20个城市的NO下降幅度在9.2%至43.4%之间，中位数为21.6%。在研究的城市中，NO下降幅度最大（>30%）的是圣何塞、洛杉矶和多伦多，下降幅度最小（<12%）的是迈阿密、明尼阿波利斯和达拉斯。这些归一化的NO变化可用于突出活动变化较大的地点，并更好地了解每个城市中导致空气质量恶化的来源。
