Ozone variability: Influence by its precursors and meteorological parameters- an investigation

Kanchana, Asuri Lakshmi; Sagar, Vijay Kumar; Pathakoti, Mahesh; Mahalakshmi, D. V.; Mallikarjun, K.; Gharai, Biswadip

doi:10.1016/j.jastp.2020.105468

Cited by 11 publications

(10 citation statements)

References 34 publications

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“…Subsequent changes in air quality associated with meteorology, long-range transport, and forest fires have been taken into account through statistical correlations to distinguish between natural and anthropogenic emissions. (Krotkov et al, 2017). The MODIS sensor on board NASA's two Earth Observing System Terra and Aqua platforms provide AOD retrievals.…”

Section: Introductionmentioning

confidence: 99%

Measurement report: An assessment of the impact of a nationwide lockdown on air pollution – a remote sensing perspective over India

Pathakoti

Muppalla²,

Hazra

et al. 2021

Atmos. Chem. Phys.

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Abstract. The nationwide lockdown was imposed over India from 25 March to 31 May 2020 with varied relaxations from phase I to phase IV to contain the spread of COVID-19. Thus, emissions from industrial and transport sectors were halted during lockdown (LD), which has resulted in a significant reduction of anthropogenic pollutants. The first two lockdown phases were strictly implemented (phase I and phase II) and hence were considered to be total lockdown (TLD) in this study. Satellite-based tropospheric columnar nitrogen dioxide (TCN) from the years 2015 to 2020, tropospheric columnar carbon monoxide (TCC) during 2019/20, and aerosol optical depth (AOD550) from the years 2014 to 2020 during phase I and phase II LD and pre-LD periods were investigated with observations from Aura OMI, Sentinel-5P TROPOMI, and Aqua and Terra MODIS. To quantify lockdown-induced changes in TCN, TCC, and AOD550, detailed statistical analysis was performed on de-trended data using the Student paired statistical t test. Results indicate that mean TCN levels over India showed a dip of 18 % compared to the previous year and also against the 5-year mean TCN levels during the phase I lockdown, which was found to be statistically significant (p value < 0.05) against the respective period. Furthermore, drastic changes in TCN levels were observed over hotspots, namely eastern region and urban cities. For example, there was a sharp decrease of 62 % and 54 % in TCN levels compared to 2019 and against 5-year mean TCN levels over New Delhi with a p value of 0.0002 (which is statistically significant) during total LD. The TCC levels were high in the northeast (NE) region during the phase I LD period, which is mainly attributed to the active fire counts in this region. However, lower TCC levels are observed in the same region due to the diminished fire counts during phase II. Further, AOD550 is reduced over the country by ∼ 16 % (Aqua and Terra) from the 6-year (2014–2019) mean AOD550 levels, with a significant reduction (Aqua MODIS 28 %) observed over the Indo-Gangetic Plain (IGP) region with a p value of ≪ 0.05. However, an increase in AOD550 levels (25 % for Terra MODIS, 15 % for Aqua MODIS) was also observed over central India during LD compared to the preceding year and found significant with a p value of 0.03. This study also reports the rate of change of TCN levels and AOD550 along with statistical metrics during the LD period.

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Section: Introductionmentioning

confidence: 99%

Measurement report: An assessment of the impact of a nationwide lockdown on air pollution – a remote sensing perspective over India

Pathakoti

Muppalla²,

Hazra

et al. 2021

Atmos. Chem. Phys.

Self Cite

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“…Since agriculture farming industry is exempted in the phase-II LD and observed active fire counts in the central India, thus observed enhancement in the TCC levels during phase-II. An increase or decrease of TCC levels in the atmosphere is mainly dominated significantly by anthropogenicactivitiescompared to natural emissions (Kanchana et al, 2020) as discussed earlier. However, comprehensive reasons for the increase of TCC levels in phase-II are not investigated in this study.…”

Section: Effect Of Ld On Tccmentioning

confidence: 72%

Measurement report: An assessment of the impact of a nationwide lockdown on air pollution – a remote sensing perspective over India

Pathakoti¹,

Muppalla²,

Hazra³

et al. 2021

Preprint

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Abstract. The nationwide lockdown was imposed over India from 25th March to 31st May 2020 with varied relaxations from phase-I to phase-IV to contain the spread of COVID-19. Thus emissions from industrial and transport sectors were halted during lockdown (LD) which resulted in a significant reduction of anthropogenic pollutants. The first two lockdown phases were strictly followed (phase-I and phase-II) and hence are considered as total lockdown (TLD) in this study. Satellite-based tropospheric columnar nitrogen dioxide (TCN) from the years 2015 to 2020, tropospheric columnar carbon monoxide (TCC) during 2019–2020 and aerosol optical depth (AOD550) from the years 2014 to 2020 during phase-I and phase-II LD and pre-LD periods were investigated with observations from Aura/OMI, Sentinel-5P/TROPOMI, and Aqua-Terra/ MODIS satellite sensors. To quantify lockdown induced changes in TCN, TCC, and AOD550, detailed statistical analysis was performed on de-trended data using student’s paired statistical t-test. Results indicate that mean TCN levels over India showed a dip of 18 % compared to the previous year and also against the 5-year mean TCN levels during the phase-I lockdown, which was found statistically significant (p-value <0.05) against the respective period. Furthermore, drastic changes in TCN levels were observed over hotspots namely the eastern region and urban cities. For example, there was a sharp decrease of 62 % and 54 % in TCN levels as compared to 2019 and against 5-years mean TCN levels over New Delhi with a p-value of 0.0002 (which is statistically significant) during total LD. The TCC levels were high in the North East (NE) region during the phase-I LD period, which is mainly attributed to the active fire counts in this region. However, lower TCC levels are observed in the same region due to the diminished fire counts during phase-II. Further, AOD550 is reduced over the country by ~16 % (Aqua and Terra) from the 6-years (2014–2019) mean AOD550 levels, with a significant reduction (Aqua/MODIS 28 %) observed over the Indo-Gangetic plains (IGP) region with a p-value of

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Section: Effect Of Ld On Tccmentioning

confidence: 99%

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2021

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The nationwide lockdown was imposed over India from 25 th March to 31 st May2020 with varied relaxations from phase-I to phase-IVto contain the spread of COVID-19. Thus emissions from industrial and transport sectorswere halted during lockdown (LD)which resulted in a significant reduction of anthropogenic pollutants. The first twolockdown phases werestrictly followed(phase-I and phase-II) and hence are considered as total lockdown (TLD) in this study. Satellite-based tropospheric columnar nitrogen dioxide (TCN) from the years 2015 to 2020, tropospheric columnar carbon monoxide (TCC) during 2019-2020 and aerosol optical depth (AOD550) from the years 2014 to 2020 during phase-I and phase-II LDand pre-LD periods were investigated with observations from Aura/OMI, Sentinel-5P/TROPOMI, and Aqua-Terra/ MODIS satellite sensors.To quantify lockdown induced changesin TCN, TCC, and AOD550, detailed statistical analysis was performed on de-trended data using student's paired statistical t-test.Results indicate that mean TCN levels over India showed a dip of 18% compared to the previous year and also against the 5-year mean TCN levelsduring the phase-I lockdown, which was found statistically significant (p-value <0.05) against the respective period. Furthermore, drastic changes in TCN levels were observed over hotspots namely the eastern region and urban cities. For example,there was a sharp decrease of 62%and 54% in TCN levels as compared to 2019 and against 5-years mean TCN levels over New Delhi with a p-value of 0.0002 (which is statistically significant) during total LD.The TCC levels werehigh in the North East (NE) region during the phase-I LD period, which is mainly attributed to the active fire counts in this region. However, lower TCC levels are observed in the same region due to the diminished fire counts during phase-II. Further, AOD550is reduced over the country by ~16 %(Aqua

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Ozone variability: Influence by its precursors and meteorological parameters- an investigation

Cited by 11 publications

References 34 publications

Measurement report: An assessment of the impact of a nationwide lockdown on air pollution – a remote sensing perspective over India

Measurement report: An assessment of the impact of a nationwide lockdown on air pollution – a remote sensing perspective over India

Measurement report: An assessment of the impact of a nationwide lockdown on air pollution – a remote sensing perspective over India

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