Surprising Changes in Aerosol Loading over India amid COVID-19 Lockdown

Pandey, Satyendra K.; Vinoj, V.

doi:10.4209/aaqr.2020.07.0466

Cited by 27 publications

(25 citation statements)

References 45 publications

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“…Despite the strict LD in the country, an unexpected increase in AOD 550 is observed by ∼ 28 % compared to the preceding year of the same period over central India (CI), M. Pathakoti et al: The impact of India's lockdown on air pollution which is predominantly dominated by dust storms (Ratnam et al, 2021) through long-range transport and prevailing meteorology (Pandey and Vinoj, 2020). Thus, to understand the prevailing meteorology over CI, phase-wise relative humidity and wind speed at pressure levels 850 and 700 hPa, respectively, were analysed as shown in Fig.…”

Section: Effect Of Ld On Aod 550mentioning

confidence: 99%

“…During phase I and phase II, the majority of the winds over CI are dominated by westerly (calm) winds with high relative humidity. Under this prevailing meteorology, calm winds contribute to slow dispersion, and high relative humidity (RH) modulates the aerosol chemistry and hygroscopic growth mechanism (Pandey and Vinoj, 2020). As a result, the increase in AOD 550 over CI is observed.…”

Section: Effect Of Ld On Aod 550mentioning

confidence: 99%

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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: Effect Of Ld On Aod 550mentioning

confidence: 99%

Section: Effect Of Ld On Aod 550mentioning

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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“…Nations across the globe have taken various measures like social distancing, travel restrictions, and complete lockdowns of different durations to slow its spread. Numerous studies have documented multiple impacts of these lockdowns and the associated decrease in anthropogenic emissions in improving the air quality (e.g., Baldasano, 2020;Bauwens et al, 2020;Collivignarelli et al, 2020;Kanniah et al, 2020;Li et al, 2020;Mahato et al, 2020;Muhammad et al, 2020;Otmani et al, 2020;Pandey and Vinoj, 2020;Stratoulias and Nuthammachot, 2020). It is well known that atmospheric aerosols directly affect the surface radiation budget by absorbing and scattering the incoming solar radiation.…”

Section: Introductionmentioning

confidence: 99%

Aerosol Induced Changes in Sea Surface Temperature Over the Bay of Bengal Due to COVID-19 Lockdown

et al. 2021

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The role of COVID-19 pandemic lockdown in improving air quality was reported extensively for land regions globally. However, limited studies have explored these over oceanic areas close to high anthropogenic activities and emissions. The Bay of Bengal (BoB) basin is one such region adjacent to the highly populated South Asian region. We find that Aerosol Optical Depth (AOD) over the BoB declined by as much as 0.1 or 30% during the peak lockdown of April 2020 compared to long-term climatology during 2003–2019. Simultaneously, the sea surface temperature (SST) rose by 0.5–1.5°C over the central and north-western parts of the BoB with an average increase of 0.83°C. We show that up to 30% of this observed warming is attributable to reduced atmospheric aerosols. The study highlights the importance of anthropogenic emissions reduction due to COVID lockdown on short-term changes to SST over ocean basins with implications to regional weather.

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“…Furthermore, it gives an estimation of PM2.5 surface concentration [56]. Measurements using satelliteborne observation and aerosol reanalysis products revealed that during lockdown (24th Mar -22nd Apr 2020) maximum decrement in AOD value is observed in eastern IGP ($40% of pre-lockdown; 20th Feb-20th Mar 2020) followed by northwest (27%) and south-India (13%) [4]. In disparity, an increment of 20% is observed in central India, the most polluted part of India.…”

Section: Aerosol Optical Depth (Aod)mentioning

confidence: 99%

“…Apart from this, there have been several reports in recent times on ambient air criteria pollutants, like, particulate matter, O3, CO and NOx that are at the helm of triggering several environmental health threats leading to comorbidity and premature deaths [2,3]. According to the 2019 Global Burden disease report, $1.67 million deaths were attributed to air pollution, which ascribed $18% of the country's total death [4]. Short-term air pollution exposure is often associated with COPD (Chronic Obstructive Pulmonary Disease), shortness of breath, dizziness, nausea, asthma, cough, and an increase in rates of co-morbid symptoms [5].…”

Section: Introductionmentioning

confidence: 99%

COVID-19 Lockdown and the Aerosphere in India: Lessons Learned on How to Reduce Air Pollution

Panda¹,

Satpathy²,

Das³

et al. 2022

Biotechnology to Combat COVID-19

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The giant increase in COVID-19 infection across India forced the government to impose strict lockdown in order to curb the pandemic. Although the stringent restrictions crippled India’s economy and poor people’s livelihood, it significantly improved the air quality of most of the polluted cities of India and rejuvenated the atmosphere. Thus, the major objective of this study is to provide a comprehensive overview of lockdown on pollutants prevailing in the atmosphere. A prominent decline in primary pollutants such as Particulate matter (PM), Black carbon (BC), Oxides of nitrogen (NOx), Carbon monoxide (CO) is observed across the country. However, lockdown had a trifling impact on Sulphur dioxide (SO2) concentration over some parts of India due to the constant operation of coal-fired thermal plants as a part of essential service. Furthermore, the sudden decline in NOx concentration disturbed the complex atmospheric chemistry and lead to an enhancement of surface ozone (O3) (secondary pollutant) in many cities of India. Thus, lockdown emerged as a unique opportunity for the atmospheric researchers, policymakers as well as stakeholders to collect baseline data of pollutants and their major sources. This will help to set new targets of air quality standards and to develop various mitigation processes to combat air pollution.

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Surprising Changes in Aerosol Loading over India amid COVID-19 Lockdown

Cited by 27 publications

References 45 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

Aerosol Induced Changes in Sea Surface Temperature Over the Bay of Bengal Due to COVID-19 Lockdown

COVID-19 Lockdown and the Aerosphere in India: Lessons Learned on How to Reduce Air Pollution

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