scholarly journals Natural processes dominate the pollution levels during COVID-19 lockdown over India

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Venkat Ratnam Madineni ◽  
Hari Prasad Dasari ◽  
Ramakrishna Karumuri ◽  
Yesubabu Viswanadhapalli ◽  
Prasad Perumal ◽  
...  
Keyword(s):  
South India ◽  
Anthropogenic Activities ◽  
Gangetic Plain ◽  
Pollution Levels ◽  
Natural Processes ◽  
Range Transport ◽  
Northwest India ◽  
Indo Gangetic Plain ◽  
Pollution Concentrations ◽  
Natural Laboratory

AbstractThe lockdown measures that were taken to combat the COVID-19 pandemic minimized anthropogenic activities and created natural laboratory conditions for studying air quality. Both observations and WRF-Chem simulations show a 20–50% reduction (compared to pre-lockdown and same period of previous year) in the concentrations of most aerosols and trace gases over Northwest India, the Indo Gangetic Plain (IGP), and the Northeast Indian regions. It is shown that this was mainly due to a 70–80% increase in the height of the boundary layer and the low emissions during lockdown. However, a 60–70% increase in the pollutants levels was observed over Central and South India including the Arabian sea and Bay of Bengal during this period, which is attributed to natural processes. Elevated (dust) aerosol layers are transported from the Middle East and Africa via long-range transport, and a decrease in the wind speed (20–40%) caused these aerosols to stagnate, enhancing the aerosol levels over Central and Southern India. A 40–60% increase in relative humidity further amplified aerosol concentrations. The results of this study suggest that besides emissions, natural processes including background meteorology and dynamics, play a crucial role in the pollution concentrations over the Indian sub-continent.

scholarly journals Large contrast in the vertical distribution of aerosol optical properties and radiative effects across the Indo-Gangetic Plain during the SWAAMI–RAWEX campaign

2018 ◽  
Vol 18 (23) ◽  
pp. 17669-17685 ◽  
Author(s):  
Aditya Vaishya ◽  
Surendran Nair Suresh Babu ◽  
Venugopalan Jayachandran ◽  
Mukunda M. Gogoi ◽  
Naduparambil Bharathan Lakshmi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Anthropogenic Activities ◽  
Eastern Coast ◽  
Biomass Combustion ◽  
Spectral Variation ◽  
Vertical Profiles ◽  
Industrial Emissions ◽  
Gangetic Plain ◽  
Indo Gangetic Plain

Abstract. Measurements of the vertical profiles of the optical properties (namely the extinction coefficient and scattering and absorption coefficients respectively σext ∕ σscat ∕ σabs) of aerosols have been made across the Indo-Gangetic Plain (IGP) using an instrumented aircraft operated from three base stations – Jodhpur (JDR), representing the semi-arid western IGP; Varanasi (VNS), the central IGP characterized by significant anthropogenic activities; and the industrialized coastal location in the eastern end of the IGP (Bhubaneswar, BBR) – just prior to the onset of the Indian summer monsoon. The vertical profiles depicted region-specific absorption characteristics, while the scattering characteristics remained fairly uniform across the region, leading to a west–east gradient in the vertical structure of single-scattering albedo (SSA). Integrated from near the ground to 3 km, the highest absorption coefficient and hence the lowest SSA occurred in the central IGP (Varanasi). Size distribution, inferred from the spectral variation of the scattering coefficient, showed a gradual shift from coarse-particle dominance in the western IGP to strong accumulation dominance in the eastern coast with the central IGP coming in between, arising from a change in the aerosol type from a predominantly natural (dust and sea salt) type in the western IGP to a highly anthropogenic type (industrial emissions, fossil fuel and biomass combustion) in the eastern IGP, with the central IGP exhibiting a mixture of both. Aerosol-induced short-wave radiative forcing, estimated using altitude-resolved SSA information, revealed significant atmospheric warming in the central IGP, while a top-of-atmosphere cooling is seen, in general, in the IGP. Atmospheric heating rate profiles, estimated using altitude-resolved SSA and column-averaged SSA, revealed considerable underestimation in the latter case, emphasizing the importance and necessity of having altitude-resolved SSA information as against a single value for the entire column.

Composition and mineralogy of iron-manganese concretions from some soils of the Indo-Gangetic plain in Northwest India

Geoderma ◽  
1977 ◽  
Vol 18 (4) ◽  
pp. 241-249 ◽  
Author(s):  
P.S Sidhu ◽  
J.L Sehgal ◽  
M.K Sinha ◽  
N.S Randhawa
Keyword(s):  
Gangetic Plain ◽  
Northwest India ◽  
Iron Manganese ◽  
Indo Gangetic Plain

scholarly journals Deposition of light-absorbing particles in glacier snow of the Sunderdhunga Valley, the southern forefront of Central Himalaya

2020 ◽  
Author(s):  
Jonas Svensson ◽  
Johan Ström ◽  
Henri Honkonen ◽  
Eija Asmi ◽  
Nathaniel B. Dkhar ◽  
...  
Keyword(s):  
Large Scale ◽  
Anthropogenic Activities ◽  
Central Himalaya ◽  
Snow Layer ◽  
Gangetic Plain ◽  
Central Himalayas ◽  
Indo Gangetic Plain ◽  
The Himalaya ◽  
Very High ◽  
Fractional Absorption

Abstract. Anthropogenic activities on the Indo-Gangetic Plain emit vast amounts of light-absorbing particles (LAP) into the atmosphere, modifying the atmospheric radiation scheme. With transport to the nearby Himalayan mountains and deposition to its surfaces the particles contribute to glacier and snowmelt via darkening of the highly reflective snow. The Central Himalayas have been identified as a region where LAP are especially pronounced in glacier snow, but still remain a region where measurements of LAP in the snow are scarce. Here we study the deposition of LAP in five snow pits sampled in 2016 (and one from 2015) from two glaciers in the Sunderdhunga valley, state of Uttarakhand, India, Central Himalaya. The snow pits display a distinct melt layer interleaved by younger snow above, and older snow below. The LAP exhibit a large vertical distribution in these different snow layers. For the analyzed elemental carbon (EC), the younger snow layers in the different pits show similarities, and can be characterized by a deposition constant of about 50 µg m−2 mm−1 while the old snow layers also indicate similar values, and can be described with deposition constant of roughly 150 µg m−2 mm−1. The melt layer, contrarily, display no similar trends between the pits. Instead, it is characterized by very high amounts of LAP, and differ in orders of magnitude for concentration between the pits. The melt layer is likely a result of strong melting that took place during the summers of 2015 and 2016. The mineral dust fractional absorption is slightly below 50 % for the young and old snow layer, whereas in the melt layer is the dominating light absorbing constituent, thus, highlighting the importance of dust in the region. Our results indicate the problems with complex topography in the Himalaya, but nonetheless, can be useful in large-scale assessments of LAP in Himalayan snow.

scholarly journals Deposition of light-absorbing particles in glacier snow of the Sunderdhunga Valley, the southern forefront of the central Himalayas

2021 ◽  
Vol 21 (4) ◽  
pp. 2931-2943
Author(s):  
Jonas Svensson ◽  
Johan Ström ◽  
Henri Honkanen ◽  
Eija Asmi ◽  
Nathaniel B. Dkhar ◽  
...  
Keyword(s):  
Large Scale ◽  
Elemental Carbon ◽  
Snow Water Equivalent ◽  
Anthropogenic Activities ◽  
Gangetic Plain ◽  
Central Himalayas ◽  
Snow Water ◽  
Indo Gangetic Plain ◽  
Very High ◽  
Fractional Absorption

Abstract. Anthropogenic activities on the Indo-Gangetic Plain emit vast amounts of light-absorbing particles (LAPs) into the atmosphere, modifying the atmospheric radiation state. With transport to the nearby Himalayas and deposition to its surfaces the particles contribute to glacier melt and snowmelt via darkening of the highly reflective snow. The central Himalayas have been identified as a region where LAPs are especially pronounced in glacier snow but still remain a region where measurements of LAPs in the snow are scarce. Here we study the deposition of LAPs in five snow pits sampled in 2016 (and one from 2015) within 1 km from each other from two glaciers in the Sunderdhunga Valley, in the state of Uttarakhand, India, in the central Himalayas. The snow pits display a distinct enriched LAP layer interleaved by younger snow above and older snow below. The LAPs exhibit a distinct vertical distribution in these different snow layers. For the analyzed elemental carbon (EC), the younger snow layers in the different pits show similarities, which can be characterized by a deposition constant of about 50 µg m−2 mm−1 snow water equivalent (SWE), while the old-snow layers also indicate similar values, described by a deposition constant of roughly 150 µg m−2 mm−1 SWE. The enriched LAP layer, contrarily, displays no similar trends between the pits. Instead, it is characterized by very high amounts of LAPs and differ in orders of magnitude for concentration between the pits. The enriched LAP layer is likely a result of strong melting that took place during the summers of 2015 and 2016, as well as possible lateral transport of LAPs. The mineral dust fractional absorption is slightly below 50 % for the young- and old-snow layers, whereas it is the dominating light-absorbing constituent in the enriched LAP layer, thus, highlighting the importance of dust in the region. Our results indicate the problems with complex topography in the Himalayas but, nonetheless, can be useful in large-scale assessments of LAPs in Himalayan snow.

scholarly journals Large contrast in the vertical distribution of aerosol optical properties and radiative effects across the Indo-Gangetic Plain during SWAAMI-RAWEX campaign

2018 ◽  
Author(s):  
Aditya Vaishya ◽  
Surendran Nair Suresh Babu ◽  
Venugopalan Jayachandran ◽  
Mukunda M. Gogoi ◽  
Naduparambil Bharathan Lakshmi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Anthropogenic Activities ◽  
Eastern Coast ◽  
Biomass Combustion ◽  
Spectral Variation ◽  
Vertical Profiles ◽  
Industrial Emissions ◽  
Gangetic Plain ◽  
Indo Gangetic Plain

Abstract. Measurements of the vertical profiles of the optical properties (namely the extinction / scattering and absorption coefficients; respectively σext / σscat / σabs) of aerosols have been made across the Indo-Gangetic Plain (IGP) using an instrumented aircraft operated from three base stations (Jodhpur (JDR) representing the semiarid western IGP; Varanasi (VNS) the central IGP characterized by significant anthropogenic activities; and the industrialised coastal location in the eastern end of the IGP (Bhubaneswar, BBR)), just prior to the onset of the Indian Summer monsoon. The vertical profiles depicted region-specific absorption characteristics, while the scattering characteristics remained fairly uniform across the region, leading to a west-east gradient in the vertical structure of single scattering albedo (SSA). Integrated from near ground to 3 km, the highest absorption coefficient and hence the lowest SSA occurred in the central IGP (Varanasi). Size distribution, inferred from the spectral variation of the scattering coefficient, showed a gradual shift from coarse particle dominance in the western IGP to strong accumulation dominance in the eastern coast with the central IGP coming in-between, arising from a change in the aerosol type from predominantly natural (dust and sea-salt) type in the western IGP to highly anthropogenic type (industrial emissions, fossil fuel and biomass combustion) in the eastern IGP; the central IGP exhibiting a mixture of both. Aerosol induced short-wave radiative forcing, estimated using altitude resolved SSA information, revealed significant atmospheric warming in the central IGP while a top-of-atmosphere cooling is seen, in general, in the IGP. Atmospheric heating rate profiles, estimated using altitude resolved SSA and column average SSA, revealed considerable underestimation in the latter case, emphasising the importance and necessity of having altitude resolved SSA information as against a single value for the entire column.

scholarly journals Chemical characterisation and source apportionment of PM1during massive loading at an urban location in Indo-Gangetic Plain: impact of local sources and long-range transport

Tellus B ◽  
2016 ◽  
Vol 68 (1) ◽  
pp. 30659 ◽  
Author(s):  
Prashant Rajput ◽  
Anil Mandaria ◽  
Lokesh Kachawa ◽  
Dharmendra Kumar Singh ◽  
Amit Kumar Singh ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Long Range ◽  
Long Range Transport ◽  
Gangetic Plain ◽  
Urban Location ◽  
Range Transport ◽  
Local Sources ◽  
Indo Gangetic Plain
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