Tropospheric NO 2 Trends over South Asia during the Last Decade (2004–2014) Using OMI Data

et al. 2020

Heliyon

The World Health Organization has declared the COVID-19 pandemic a global public health emergency. Many countries of the world, including India, closed their borders and imposed a nationwide lockdown. In India, the lockdown was declared on March 24 for 21 days (March 25-April 14, 2020) and was later extended until May 3, 2020. During the lockdown, all major anthropogenic activities, which contribute to atmospheric pollution (such as industries, vehicles, and businesses), were restricted. The current study examines the impact of the lockdown on tropospheric NO 2 concentrations. Satellite-based ozone monitoring instrument sensor data were analyzed in order to investigate the variations in tropospheric NO 2 concentrations. The results showed that from March 1 to 21, 2020, the average tropospheric NO 2 concentration was 214.4 Â10 13 molecule cm À2 over India, and it subsequently decreased by 12.1% over the next four weeks. An increase of 0.8% in tropospheric NO 2 concentrations was observed for the same period in 2019 and hence, the reduced tropospheric NO 2 concentrations can be attributed to restricted anthropogenic activities during the lockdown. In the absence of significant activities, the contribution of various sources was estimated, and the emissions from biomass burning were identified as a major source of tropospheric NO 2 during the lockdown. The findings of this study provide an opportunity to understand the mechanism of tropospheric NO 2 emissions over India, in order to improve air quality modeling and management strategies.

Section: Resultsmentioning

confidence: 99%

COVID-19 lockdown and its impact on tropospheric NO2 concentrations over India using satellite-based data

Biswal

et al. 2020

Heliyon

Atmospheric Environment

“…NO X and SO 2 pollution from power plants have increased by more than 70% from 1996 to 2014 and 2005-2012 respectively as observed by temporal trend observations from satellites Lu et al, 2013]. Trends in tropospheric NO 2 at selected industrial areas have been found to increase at a rate of 1 to 9% per year [Ramachandran et al, 2013], with a regional average decadal increase from 2004-2015 on the order of 14% [Zia ul-Haq et al, 2015]. The largest growth in VCDs is over areas of high population density in the north, attributable to enhanced electricity production, industrial activity, transportation, and crop burning, trends not as prominent in southern India [Duncan et al, 2015;Zia ul-Haq et al, 2015].…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 82%

“…Trends in tropospheric NO 2 at selected industrial areas have been found to increase at a rate of 1 to 9% per year [Ramachandran et al, 2013], with a regional average decadal increase from 2004-2015 on the order of 14% [Zia ul-Haq et al, 2015]. The largest growth in VCDs is over areas of high population density in the north, attributable to enhanced electricity production, industrial activity, transportation, and crop burning, trends not as prominent in southern India [Duncan et al, 2015;Zia ul-Haq et al, 2015]. However, recent developments, including slight stagnation due to economic slow-down [Hilboll et al, 2017], indicate the complex nature of pollution trends in the region which may be unaccounted for in current emissions inventories for the region.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Constraining the uncertainty in emissions over India with a regional air quality model evaluation

Karambelas

Holloway

Kiesewetter

et al. 2018

To evaluate uncertainty in the spatial distribution of air emissions over India, we compare satellite and surface observations with simulations from the U.S. Environmental Protection Agency (EPA) Community Multi-Scale Air Quality (CMAQ) model. Seasonally representative simulations were completed for January, April, July, and October 2010 at 36km x 36km using anthropogenic emissions from the Greenhouse Gas-Air Pollution Interaction and Synergies (GAINS) model following version 5a of the Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants project (ECLIPSE v5a). We use both tropospheric columns from the Ozone Monitoring Instrument (OMI) and surface observations from the Central Pollution Control Board (CPCB) to closely examine modeled nitrogen dioxide (NO 2) biases in urban and rural regions across India. Spatial average evaluation with satellite retrievals indicate a low bias in the modeled tropospheric column (-63.3%), which reflects broad low-biases in majority non-urban regions (-70.1% in rural areas) across the sub-continent to slightly lesser low biases reflected in semi-urban areas (-44.7%), with the threshold between semi-urban and rural defined as 400 people per km 2. In contrast, modeled surface NO 2 concentrations exhibit a slight high bias of +15.6% when compared to surface CPCB observations predominantly located in urban areas. Conversely, in examining extremely population dense urban regions with more than 5000 people per km 2 (dense-urban), we find model overestimates in both the column (+57.8) and at the surface (+131.2%) compared to observations. Based on these results, we find that existing emission fields for India may overestimate urban emissions in densely populated regions and underestimate rural emissions. However, if we rely on model evaluation with predominantly urban surface observations from the CPCB, comparisons reflect model high biases, contradictory to the knowledge gained using satellite observations. Satellites thus serve as an important emissions and model evaluation

“…OMI AURA satellite observation of NO 2 concentrations [ 19 , 24 ] over India shows high concentrations at few locations, one of the locations correspond to the location of the seven coal-fired power plants (Singrauli). The NO 2 and AOD show higher correlation based on satellite data [ 19 , 20 , 21 , 25 ]. The higher tropospheric NO 2 concentrations over the Singrauli area, seen from the OMI AURA satellite ( Figure 1 ) is considered for the in-situ BC and aerosol measurement.…”

Section: Methodsmentioning

confidence: 99%

“…The black carbon concentration absorbs Sun radiations and impacts global climate as well as regional climate and monsoon [ 6 , 17 ]. Coal-fired power plants are densely located in the Indo-Gangetic Plain (IGP) and are considered as one of the sources of atmospheric pollution in the IGP [ 18 , 19 , 20 , 21 , 22 , 23 ]. The coal-fired thermal power plants are one of the major energy sources in India, the density of these power plants are very high in the northern and south-east parts of India, especially in the IGP.…”

Section: Introductionmentioning

confidence: 99%

Elevated Black Carbon Concentrations and Atmospheric Pollution around Singrauli Coal-Fired Thermal Power Plants (India) Using Ground and Satellite Data

Kumar

2018

IJERPH

The tropospheric NO2 concentration from OMI AURA always shows high concentrations of NO2 at a few locations in India, one of the high concentrations of NO2 hotspots is associated with the locations of seven coal-fired Thermal Power plants (TPPs) in Singrauli. Emissions from TPPs are among the major sources of black carbon (BC) soot in the atmosphere. Knowledge of BC emissions from TPPs is important in characterizing regional carbonaceous particulate emissions, understanding the fog/haze/smog formation, evaluating regional climate forcing, modeling aerosol optical parameters and concentrations of black carbon, and evaluating human health. Furthermore, elevated BC concentrations, over the Indo-Gangetic Plain (IGP) and the Himalayan foothills, have emerged as an important subject to estimate the effects of deposition and atmospheric warming of BC on the accelerated melting of snow and glaciers in the Himalaya. For the first time, this study reports BC concentrations and aerosol optical parameters near dense coal-fired power plants and open cast coal mining adjacent to the east IGP. In-situ measurements were carried out in Singrauli (located in south-east IGP) at a fixed site about 10 km from power plants and in transit measurements in close proximity to the plants, for few days in the month of January and March 2013. At the fixed site, BC concentration up to the 95 μgm−3 is observed with strong diurnal variations. BC concentration shows two maxima peaks during early morning and evening hours. High BC concentrations are observed in close proximity to the coal-fired TPPs (>200 μgm−3), compared to the outside domain of our study region. Co-located ground-based sunphotometer measurements of aerosol optical depth (AOD) show strong spatial variability at the fixed site, with AOD in the range 0.38–0.58, and the highest AOD in the range 0.7–0.95 near the TPPs in transit measurements (similar to the peak of BC concentrations). Additionally, the Angstrom exponent was found to be in the range 0.4–1.0 (maximum in the morning time) and highest in the proximity of TPPs (~1.0), suggesting abundance of fine particulates, whereas there was low Angstrom exponent over the surrounding coal mining areas. Low Angstrom exponent is characterized by dust from the unpaved roads and nearby coal mining areas. MODIS derived daily AOD shows a good match with the MICROTOPS AOD. The CALIPSO derived subtypes of the aerosol plot shows that the aerosols over Singrauli region are mainly dust, polluted dust, and elevated smoke. The preliminary study for few days provides information about the BC concentrations and aerosol optical properties from Singrauli (one of the NO2 hotspot locations in India). This preliminary study suggests that long-term continuous monitoring of BC is needed to understand the BC concentrations and aerosol optical properties for better quantification and the estimation of the emission to evaluate radiative forcing in the region.