US COVID-19 shutdown shows importance of background NO2 in inferring nitrogen oxide (NOx) emissions from satellite NO2 observations (N/A limited co-author role)
Data used in this study are: (1) 24 hour averaged surface NO2 data for March-August for 2019 & 2020; (2) a total of about 328 AQS sites that have no data gaps; (3) a trend analysis for a subset of those AQS sites that extends back to 2005; and (4) OMI (2005-2020) and TROPOMI (2018-2020) satellite-based data for NO2 …