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dc.contributor.authorRatnam, Madineni Venkat
dc.contributor.authorPrasad, Perumal
dc.contributor.authorRaj, Sivan Thankamani Akhil
dc.contributor.authorHoteit, Ibrahim
dc.date.accessioned2021-07-13T13:03:42Z
dc.date.available2021-07-13T13:03:42Z
dc.date.issued2021
dc.date.submitted2020-07-13
dc.identifier.citationVenkat Ratnam, M., Prasad, P., Akhil Raj, S. T., & Hoteit, I. (2021). Effect of Lockdown due to COVID-19 on the Aerosol and Trace Gases Spatial Distribution over India and Adjoining Regions. Aerosol and Air Quality Research, 21(2), 200397. doi:10.4209/aaqr.2020.07.0397
dc.identifier.issn2071-1409
dc.identifier.issn1680-8584
dc.identifier.doi10.4209/aaqr.2020.07.0397
dc.identifier.urihttp://hdl.handle.net/10754/670182
dc.description.abstractSignificant improvement in the air quality has been reported during the ‘Lockdown’ being implemented due to the Corona Virus Disease (COVID-19) pandemic in several parts of the globe. Using Ozone Monitoring Instrument (OMI) satellite measurements, we found a 50–60% reduction in the mean tropospheric columnar Nitrogen dioxide (NO2) and planetary boundary layer Sulphur dioxide (SO2) levels over India and adjoining regions during the lockdown (25 March–7 April 2020) compared to the pre-lockdown periods (8–21 March 2020). Similar decreases in aerosol concentrations over Indo-Gangetic Plain (IGP) and south India during lockdown are noticed in Moderate Resolution Imaging Spectroradiometer (MODIS) measurements, reaching the lowest values in the satellite era. Surprisingly, aerosol concentrations increased significantly (50–70%) during lockdown over central India when compared to pre-lockdown and climatology (2001– 2019). A Concentration Weighted Trajectory analysis suggests that the air masses traveling from middle-east and Africa are the potential sources for the observed high aerosol concentrations over central India. Changes in the background meteorology (decrease in wind speed and increase in water vapour) during the lockdown made these aerosols stagnant and increased their size over central India, leading to higher AOD. These results suggest that natural sources (long-range transport) dominate anthropogenic pollution sources over India and adjoining regions, at least during the dry season. This finding is important to argue against the common belief that Asian countries are the main sources of pollution when long-range transport, which is a natural source, is the main cause. Lockdown has provided an opportunity to test this through a natural simulation by turning down the anthropogenic activities.
dc.description.sponsorshipWe thank OMI, MODIS, HYSPLIT, ERA-5 and NCEP/NCAR teams for making observations freely available through their respective sites. We thank Sai Krishanaveni and Chaithanya D Jain for providing AOD data and NO2 and SO2 data, respectively, used in the present study. We would like to thank B.V. Krishna Murthy and A. Jayaraman for fruitful discussions.
dc.publisherTaiwan Association for Aerosol Research
dc.relation.urlhttps://aaqr.org/articles/aaqr-20-07-covid-0397
dc.rightsThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectIndian continent
dc.subjectCOVID-19
dc.subjectAir pollution
dc.subjectAerosol
dc.subjectLong-range transport
dc.subjectMODIS
dc.subjectOMI
dc.titleEffect of Lockdown due to COVID-19 on the Aerosol and Trace Gases Spatial Distribution over India and Adjoining Regions
dc.typeArticle
dc.contributor.departmentEarth Science and Engineering Program
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.identifier.journalAEROSOL AND AIR QUALITY RESEARCH
dc.identifier.wosutWOS:000627593600010
dc.eprint.versionPublisher's Version/PDF
dc.contributor.institutionNational Atmospheric Research Laboratory (NARL), Gadanki, 517112, India
dc.identifier.volume21
dc.identifier.issue2
dc.identifier.pages200397
kaust.personHoteit, Ibrahim
dc.date.accepted2020-10-20
dc.identifier.eid2-s2.0-85098696224
refterms.dateFOA2021-07-13T13:04:47Z
dc.date.published-online2021
dc.date.published-print2021


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This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.
Except where otherwise noted, this item's license is described as This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.