Preprints
https://doi.org/10.5194/egusphere-2023-346
https://doi.org/10.5194/egusphere-2023-346
28 Mar 2023
 | 28 Mar 2023

Nitrogen oxides emissions from selected cities in North America, Europe, and East Asia observed by TROPOMI before and after the COVID-19 pandemic

Chantelle R. Lonsdale and Kang Sun

Abstract. Nitrogen oxides (NOx = NO + NO2) emissions are estimated in three regions in the Northern hemisphere, generally located in North America, Europe, and East Asia, by calculating the directional derivatives of NO2 column amounts observed by the TROPOMI instrument with respect to the horizontal wind vectors. We present monthly averaged emissions from 1 May 2018 to 31 January 2023 to capture variations before and after the COVID-19 pandemic. We focus on a diverse collection of 54 cities, 18 in each region. A spatial resolution of 0.04° resolves intracity emission variations and reveals NOx emission hot spots at city cores, industrial areas, and sea ports. For each selected city, COVID-19-induced changes in NOx emissions are estimated by comparing monthly and annually averaged values to the pre-COVID-19 year of 2019. While emission reductions are initially found during the first outbreak of COVID-19 in early 2020 in most cities, the cities' paths diverge afterwards. We group the selected cities into 4 clusters according to their normalized annual NOx emissions in 2019–2022 using an unsupervised learning algorithm. All but one selected North American cities fall into cluster 1 characterized by weak emission reduction in 2020 (−7 % relative to 2019) and increase in 2022 by +5 %. Cluster 2 contains mostly European cities and is characterized by the largest reduction in 2020 (−31 %), whereas the selected East Asian cities generally fall into clusters 3 and 4 with the largest impacts in 2022 (−25 % and −37 %). This directional derivative approach has been implemented in object-oriented, open-source Python and is available publicly for high-resolution and low-latency emission estimation for different regions, atmospheric species, and satellite instruments.

Journal article(s) based on this preprint

08 Aug 2023
Nitrogen oxides emissions from selected cities in North America, Europe, and East Asia observed by the TROPOspheric Monitoring Instrument (TROPOMI) before and after the COVID-19 pandemic
Chantelle R. Lonsdale and Kang Sun
Atmos. Chem. Phys., 23, 8727–8748, https://doi.org/10.5194/acp-23-8727-2023,https://doi.org/10.5194/acp-23-8727-2023, 2023
Short summary

Chantelle R. Lonsdale and Kang Sun

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-346', Anonymous Referee #1, 20 May 2023
  • RC2: 'Comment on egusphere-2023-346', Anonymous Referee #2, 23 May 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-346', Anonymous Referee #1, 20 May 2023
  • RC2: 'Comment on egusphere-2023-346', Anonymous Referee #2, 23 May 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Kang Sun on behalf of the Authors (30 May 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (10 Jun 2023) by Tao Wang
RR by Anonymous Referee #2 (13 Jun 2023)
RR by Anonymous Referee #1 (28 Jun 2023)
ED: Reconsider after major revisions (28 Jun 2023) by Tao Wang
AR by Kang Sun on behalf of the Authors (28 Jun 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (07 Jul 2023) by Tao Wang
AR by Kang Sun on behalf of the Authors (07 Jul 2023)  Manuscript 

Journal article(s) based on this preprint

08 Aug 2023
Nitrogen oxides emissions from selected cities in North America, Europe, and East Asia observed by the TROPOspheric Monitoring Instrument (TROPOMI) before and after the COVID-19 pandemic
Chantelle R. Lonsdale and Kang Sun
Atmos. Chem. Phys., 23, 8727–8748, https://doi.org/10.5194/acp-23-8727-2023,https://doi.org/10.5194/acp-23-8727-2023, 2023
Short summary

Chantelle R. Lonsdale and Kang Sun

Chantelle R. Lonsdale and Kang Sun

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Latest update: 08 Aug 2023
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Short summary
The COVID-19 pandemic, which was caused by the SARS-CoV-2 virus emerged in 2019 and its still evolving variants, has resulted in unprecedented shifts in human activities and anthropogenic emissions to the Earth's atmosphere. We present monthly nitrogen oxides emissions over three major continents from May 2018 to January 2023 to capture variations before and after the COVID-19 pandemic. We focus on a diverse collection of 54 cities to quantify the COVID-19-induced perturbations.