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US COVID‐19 Shutdown Demonstrates Importance of Background NO 2 in Inferring NO x Emissions From Satellite NO 2 Observations
Author(s) -
Qu Zhen,
Jacob Daniel J.,
Silvern Rachel F.,
Shah Viral,
Campbell Patrick C.,
Valin Lukas C.,
Murray Lee T.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl092783
Subject(s) - environmental science , ozone monitoring instrument , satellite , nitrogen dioxide , ozone , covid-19 , atmospheric sciences , meteorology , troposphere , shutdown , remote sensing , climatology , outbreak , geography , physics , geology , medicine , disease , pathology , astronomy , virology , infectious disease (medical specialty) , nuclear physics , biology
Satellite nitrogen dioxide (NO 2 ) measurements are used extensively to infer nitrogen oxide emissions and their trends, but interpretation can be complicated by background contributions to the NO 2 column sensed from space. We use the step decrease of US anthropogenic emissions from the COVID‐19 shutdown to compare the responses of NO 2 concentrations observed at surface network sites and from satellites (Ozone Monitoring Instrument [OMI], Tropospheric Ozone Monitoring Instrument [TROPOMI]). After correcting for differences in meteorology, surface NO 2 measurements for 2020 show decreases of 20% in March–April and 10% in May–August compared to 2019. The satellites show much weaker responses in March–June and no decrease in July–August, consistent with a large background contribution to the NO 2 column. Inspection of the long‐term OMI trend over remote US regions shows a rising summertime NO 2 background from 2010 to 2019 potentially attributable to wildfires.