Spatio-temporal characterization of tropospheric ozone and its precursor pollutants NO2 and HCHO over South Asia

dc.contributor.authorBaruah, Ujjal Deka
dc.contributor.authorRobeson, Scott M.
dc.contributor.authorSaikia, Anup
dc.contributor.authorMili, Nitashree
dc.contributor.authorSung, Kang
dc.contributor.authorChand, Pritam
dc.date.accessioned2024-01-21T10:51:49Z
dc.date.accessioned2024-08-14T06:47:32Z
dc.date.available2024-01-21T10:51:49Z
dc.date.available2024-08-14T06:47:32Z
dc.date.issued2021-10-25T00:00:00
dc.description.abstractIn recent decades, South Asia has experienced declining air quality, with much of the attention being focused on extremely high levels of particulate matter. Here, we analyze tropospheric ozone (O3), formaldehyde (HCHO), and nitrogen dioxide (NO2) to assess other measures of air quality across South Asia from 2008 to 2018. The IASI-Forli retrieved tropospheric ozone data was validated with ozonesonde, reanalysis (ERA5), satellite (TES), and model simulation products (GEOS-Chem and TOMCAT/SLIMCAT). Space-based observations of these three trace gases were used to conduct a spatio temporal analysis over South Asia using trend analysis (Theil-Sen and linear regression), change-point detection (Pettitt's test), and hotspot identification (Getis-Ord Gi*). We used the formaldehyde-nitrogen dioxide ratio (FNR) to identify NOx limited, VOC limited, and transitional regimes in South Asia. Counter to previous studies, a statistically significant decrease of HCHO (?0.0041 DU yr?1) and O3 (?0.064 DU yr?1) was detected for South Asia; however, NO2 is increasing the 0.001 DU yr?1 over South Asia during 2008�18. The Indo-Gangetic Plains emerged as being critically affected by the three trace gases. Certain parts of southern and south-eastern India are gradually emerging as NO2 and HCHO hotpots. No significant O3 hotspots were discernible, though coldspots existed along the Himalaya belt of India, Nepal, and Bhutan and mountainous tracts of Pakistan. FNR indicates the reduction of NOx in NOx-limited regime of the Indo-Gangetic Plains reduced the formation of tropospheric O3 over South Asia. � 2021 Elsevier B.V.en_US
dc.identifier.doi10.1016/j.scitotenv.2021.151135
dc.identifier.issn489697
dc.identifier.urihttp://10.2.3.109/handle/32116/4078
dc.identifier.urlhttps://linkinghub.elsevier.com/retrieve/pii/S0048969721062136
dc.language.isoen_USen_US
dc.publisherElsevier B.V.en_US
dc.subjectFNRen_US
dc.subjectHCHOen_US
dc.subjectNO<sub>2</sub>en_US
dc.subjectSouth Asiaen_US
dc.subjecttrenden_US
dc.subjectTropospheric ozoneen_US
dc.titleSpatio-temporal characterization of tropospheric ozone and its precursor pollutants NO2 and HCHO over South Asiaen_US
dc.title.journalScience of the Total Environmenten_US
dc.typeArticleen_US
dc.type.accesstypeClosed Accessen_US

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