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\begin{document}

\title{Correlating Economic Activity Indicators and Tropospheric Column
Nitrogen Dioxide during COVID-19 Pandemic in the United States}



\author[1]{Zigang Wei}%
\author[2]{Shobha Kondragunta}%
\author[3]{Kai Yang}%
\author[1]{Hai Zhang}%
\author[4]{Brian McDonald}%
\affil[1]{I.M. Systems Group Inc., NOAA/NESDIS/STAR, College Park, MD, United States}%
\affil[2]{NOAA College Park, College Park, MD, United States}%
\affil[3]{University of Maryland College Park, College Park, MD}%
\affil[4]{Chemical Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, CO, United States}%


\vspace{-1em}



  
  \date{May 18, 2024}


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\begin{abstract}
Most countries around the world took actions to control COVID-19 spread
that included social distancing, limiting air and ground travel, closing
schools, suspending sports leagues, closing factories etc., leading to
economic shutdown. The reduced traffic and human movement compared to
Business as Usual (BAU) scenario was tracked by Apple and Android
cellphone use; the data showed substantial reductions in mobility in
most metropolitan areas. For example in Washington D.C., average
distance traveled by people was \textasciitilde{}13 km and by April when
lockdown was in full effect, the distance reduced to \textasciitilde{}5
km. Consistent with reduced mobility, air quality as indicated by
satellite observations decreased substantially. Granted that year to
year variability in weather patterns can have influence on observed NO2
and aerosol concentrations, but the drop in tropospheric nitrogen
dioxide (NO2) observed by Sentinel 5P Tropospheric Ozone Monitoring
Instrument (TROPOMI) and Suomi NPP Ozone Mapping Profiling Suite (OMPS)
observations of NO2 was significant; reductions in observed NO2 were
between 15\% to 50\% between February and April 2020 depending on
location and similar reductions in NO2 amount in March and April 2020
compared to March and April 2019. Further, the changes in NO2 across the
continental U.S. between 2020 and 2019 correlated well with on-road
emissions but did not correlate with changes in emissions from power
plants. In the first quarter of 2020, the total amount of NOx emitted on
road were 200 times and 7 times larger than that from power plants in LA
and NYC, respectively. These findings confirm that power plants are no
longer the major source of NO2 in the United States. We also found
positive correlation between NO2 and Suomi NPP Visible Infrared Imaging
Radiometer Suite (VIIRS) aerosol optical depth measurements in these
urban regions indicating common source sectors for NO2 and
aerosols/aerosol precursors.%
\end{abstract}%



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