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Spatiotemporal variability of peroxy acyl nitrates (PANs) over megacities from satellite observations

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dc.contributor.authorShogrin, Madison J., author
dc.contributor.authorFischer, Emily V., advisor
dc.contributor.authorPayne, Vivienne H., committee member
dc.contributor.authorPierce, Jeffrey, committee member
dc.contributor.authorMiller, Steven, committee member
dc.contributor.authorMagzamen, Sheryl, committee member
dc.date.accessioned2023-06-01T17:27:01Z
dc.date.available2023-06-01T17:27:01Z
dc.date.issued2023
dc.description.abstractPeroxy acyl nitrates (PANs) are photochemical pollutants with implications for health and atmospheric oxidation capacity. PANs are formed via the oxidation of non-methane volatile organic compounds (NMVOCs) in the presence of nitrogen oxide radicals (NOx = NO + NO2). PANs serve as reservoir species and sources for NOx in outflow regions of megacities, facilitating O3 production downwind. While urban environments are large sources of PANs, in-situ observations in urban areas are generally limited. Here we use satellite measurements of PANs from the Tropospheric Emission Spectrometer (TES) and the S-NPP Cross-Track Infrared Sounder (CrIS) to evaluate the spatiotemporal variability of PANs over and surrounding 9 megacities: Mexico City, Beijing, Los Angeles, Tokyo, São Paulo, Delhi, Mumbai, Lagos, and Karachi. We use monthly mean values of PANs to determine the seasonal cycle within the urban center of megacities. We find pronounced seasonal cycles of PANs in megacities and seasonal maxima in PANs correspond to seasonal peaks in local photochemical activity. Local fire activity can explain some of the observed interannual variability in PANs over and around megacities. We use S-NPP CrIS data to probe the spatial outflow pattern of PANs produced within urban Mexico City during the month with the largest mixing ratios of PANs (April). Peak outflow in April occurs to the northeast of the city and over the mountains south of the city. Outflow to the northwest appears infrequent. CrIS is used to further explore changes in PANs associated with substantial declines in megacity NOx in response to the COVID-19 pandemic. We only identify two cities over which PANs changed significantly in response to NOx perturbations: Beijing and Los Angeles. This work demonstrates that the space-based observations provided by CrIS and TES can increase understanding of the spatiotemporal variability and sensitivity to precursor emissions of PANs over and around global megacities.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierShogrin_colostate_0053N_17616.pdf
dc.identifier.urihttps://hdl.handle.net/10217/236563
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2020-
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectmegacity
dc.subjectphotochemistry
dc.subjectsatellite
dc.subjectPAN
dc.subjectCOVID-19
dc.subjectremote sensing
dc.titleSpatiotemporal variability of peroxy acyl nitrates (PANs) over megacities from satellite observations
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineAtmospheric Science
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

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