Vertical and horizontal distribution of submicron aerosol chemical composition and physical characteristics across northern India during pre-monsoon and monsoon seasons

Abstract. The vertical distribution in the physical and chemical properties of submicron aerosol has been characterised across northern India for the first time using airborne in situ measurements. This study focusses primarily on the Indo-Gangetic Plain, a low-lying area in the north of India which commonly experiences high aerosol mass concentrations prior to the monsoon season. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights in the region during the 2016 pre-monsoon (11 and 12 June) and monsoon (30 June to 11 July) seasons. Inside the Indo-Gangetic Plain boundary layer, organic matter dominated the submicron aerosol mass (43&thinsp;%) followed by sulfate (29&thinsp;%), ammonium (14&thinsp;%), nitrate (7&thinsp;%) and black carbon (7&thinsp;%). However, outside the Indo-Gangetic Plain, sulfate was the dominant species, contributing 44&thinsp;% to the total submicron aerosol mass in the boundary layer, followed by organic matter (30&thinsp;%), ammonium (14&thinsp;%), nitrate (6&thinsp;%) and black carbon (6&thinsp;%). Chlorine mass concentrations were negligible throughout the campaign. Black carbon mass concentrations were higher inside the Indo-Gangetic Plain (2&thinsp;µg&thinsp;m−3) compared to outside (1&thinsp;µg&thinsp;m−3). Nitrate appeared to be controlled by thermodynamic processes, with increased mass concentration in conditions of lower temperature and higher relative humidity. Increased mass and number concentrations were observed inside the Indo-Gangetic Plain and the aerosol was more absorbing in this region, whereas outside the Indo-Gangetic Plain the aerosol was larger in size and more scattered in nature, suggesting greater dust presence, especially in north-western India. The aerosol composition remained largely similar as the monsoon season progressed, but the total aerosol mass concentrations decreased by ∼50&thinsp;% as the rainfall arrived; the pre-monsoon average total mass concentration was 30&thinsp;µg&thinsp;m−3 compared to a monsoon average total mass concentration of 10–20&thinsp;µg&thinsp;m−3. However, this mass concentration decrease was less noteworthy (∼20&thinsp;%–30&thinsp;%) over the Indo-Gangetic Plain, likely due to the strength of emission sources in this region. Decreases occurred in coarse mode aerosol, with the fine mode fraction increasing with monsoon arrival. In the aerosol vertical profile, inside the Indo-Gangetic Plain during the pre-monsoon, organic aerosol and absorbing aerosol species dominated in the lower atmosphere (&lt;1.5&thinsp;km), with sulfate, dust and other scattering aerosol species enhanced in an elevated aerosol layer above 1.5&thinsp;km with maximum aerosol height ∼6&thinsp;km. The elevated concentration of dust at altitudes &gt;1.5&thinsp;km is a clear indication of dust transport from the Great Indian Desert, also called the Thar Desert, in north-western India. As the monsoon progressed into this region, the elevated aerosol layer diminished, the aerosol maximum height reduced to ∼2&thinsp;km. The dust and sulfate-dominated aerosol layer aloft was removed upon monsoon arrival, highlighted by an increase in fine mode fraction throughout the profile.

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Vertical and horizontal distribution of sub-micron aerosol chemical composition and physical characteristics across Northern India, during the pre-monsoon and monsoon seasons

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acp-2018-1109 ◽

2018 ◽

pp. 1-31

Author(s):

James Brooks ◽

James D. Allan ◽

Paul I. Williams ◽

Dantong Liu ◽

Cathryn Fox ◽

...

Keyword(s):

Black Carbon ◽

Total Mass ◽

Mass Concentration ◽

Monsoon Season ◽

Aerosol Layer ◽

Gangetic Plain ◽

Submicron Aerosol ◽

Aerosol Mass ◽

Indo Gangetic Plain ◽

Mass Concentrations

Abstract. The vertical distribution in the physical and chemical properties of submicron aerosol has been characterised across northern India for the first time using airborne in-situ measurements. This study focusses primarily on the Indo-Gangetic Plain, a low-lying area in the north of India which commonly experiences high aerosol mass concentrations prior to the monsoon season. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights in the region during the 2016 pre-monsoon (11th and 12th June) and monsoon (30th June to 11th July) seasons. Inside the Indo-Gangetic Plain boundary layer, organic matter dominated the submicron aerosol mass (43&thinsp;%) followed by sulphate (29&thinsp;%), ammonium (14&thinsp;%), nitrate (7&thinsp;%) and black carbon (7&thinsp;%). However, outside the Indo-Gangetic Plain, sulphate was the dominant species contributing 44&thinsp;% to the total submicron aerosol mass in the boundary layer, followed by organic matter (30&thinsp;%), ammonium (14&thinsp;%), nitrate (6&thinsp;%) and black carbon (6&thinsp;%). Chlorine mass concentrations were negligible throughout the campaign. Black carbon mass concentrations were higher inside the Indo-Gangetic Plain (2&thinsp;µg/m3 std) compared to outside (1&thinsp;µg/m3 std). Nitrate appeared to be controlled by thermodynamic processes, with increased mass concentration in conditions of lower temperature and higher relative humidity. Increased mass and number concentrations were observed inside the Indo-Gangetic Plain and the aerosol was more absorbing in this region, whereas outside the Indo-Gangetic Plain the aerosol was larger in size and more scattering in nature, suggesting greater dust presence especially in northwest India. The aerosol composition remained largely similar as the monsoon season progressed, but the total aerosol mass concentrations decreased by ~&thinsp;50&thinsp;% as the rainfall arrived; the pre-monsoon average total mass concentration was 30&thinsp;µg/m3 std compared to a monsoon average total mass concentration of 10&ndash;20&thinsp;µg/m3 std. However, this mass concentration decrease was less noteworthy (~&thinsp;20&ndash;30&thinsp;%) over the Indo-Gangetic Plain, likely due to the strength of emission sources in this region. Decreases occurred in coarse mode aerosol, with the fine mode fraction increasing with monsoon arrival. In the aerosol vertical profile, inside the Indo-Gangetic Plain during the pre-monsoon, organic aerosol and absorbing aerosol species dominated in the lower atmosphere (<&thinsp;1.5&thinsp;km) with sulphate, dust and other scattering aerosol species enhanced in an elevated aerosol layer above 1.5&thinsp;km with maximum aerosol height ~&thinsp;6&thinsp;km. As the monsoon progressed into this region, the elevated aerosol layer diminished, the aerosol maximum height reduced to ~&thinsp;2&thinsp;km and the total mass concentrations decreased by ~&thinsp;50&thinsp;%. The dust and sulphate-dominated aerosol layer aloft was removed upon monsoon arrival, highlighted by an increase in fine mode fraction throughout the profile.

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Airborne in situ measurements of aerosol size distributions and black carbon across the Indo-Gangetic Plain during SWAAMI–RAWEX

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-8593-2020 ◽

2020 ◽

Vol 20 (14) ◽

pp. 8593-8610 ◽

Cited By ~ 1

Author(s):

Mukunda Madhab Gogoi ◽

Venugopalan Nair Jayachandran ◽

Aditya Vaishya ◽

Surendran Nair Suresh Babu ◽

Sreedharan Krishnakumari Satheesh ◽

...

Keyword(s):

Black Carbon ◽

Mass Fraction ◽

Aerosol Size Distribution ◽

Size Distributions ◽

Gangetic Plain ◽

Airborne Measurements ◽

Coarse Mode ◽

Indo Gangetic Plain ◽

Very High ◽

Mass Concentrations

Abstract. During the combined South-West Asian Aerosol–Monsoon Interactions and Regional Aerosol Warming Experiment (SWAAMI–RAWEX), collocated airborne measurements of aerosol number–size distributions in the size (diameter) regime 0.5 to 20 µm and black carbon (BC) mass concentrations were made across the Indo-Gangetic Plain (IGP), for the first time, from three distinct locations, just prior to the onset of the Indian summer monsoon. These measurements provided an east–west transect of region-specific properties of aerosols as the environment transformed from mostly arid conditions of the western IGP (represented by Jodhpur, JDR) having dominance of natural aerosols to the central IGP (represented by Varanasi, VNS) having very high anthropogenic emissions, to the eastern IGP (represented by the coastal station Bhubaneswar, BBR) characterized by a mixture of the IGP outflow and marine aerosols. Despite these, the aerosol size distribution revealed an increase in coarse mode concentration and coarse mode mass fraction (fractional contribution to the total aerosol mass) with the increase in altitude across the entire IGP, especially above the well-mixed region. Consequently, both the mode radii and geometric mean radii of the size distributions showed an increase with altitude. However, near the surface and within the atmospheric boundary layer (ABL), the features were specific to the different subregions, with the highest coarse mode mass fraction (FMC∼72 %) in the western IGP and highest accumulation fraction in the central IGP with the eastern IGP in between. The elevated coarse mode fraction is attributed to mineral dust load arising from local production as well as due to advection from the west. This was further corroborated by data from the Cloud-Aerosol Transport System (CATS) on board the International Space Station (ISS), which also revealed that the vertical extent of dust aerosols reached as high as 5 km during this period. Mass concentrations of BC were moderate (∼1 µg m−3) with very little altitude variation up to 3.5 km, except over VNS where very high concentrations were seen near the surface and within the ABL. The BC-induced atmospheric heating rate was highest near the surface at VNS (∼0.81 K d−1), while showing an increasing pattern with altitude at BBR (∼0.35 K d−1 at the ceiling altitude).

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Black Carbon and Elemental Carbon from Postharvest Agricultural-Waste Burning Emissions in the Indo-Gangetic Plain

Advances in Meteorology ◽

10.1155/2014/179301 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 25

Author(s):

Atinderpal Singh ◽

Prashant Rajput ◽

Deepti Sharma ◽

M. M. Sarin ◽

Darshan Singh

Keyword(s):

Black Carbon ◽

Elemental Carbon ◽

Agricultural Waste ◽

Absorption Efficiency ◽

High Mass ◽

Gangetic Plain ◽

Entire Study ◽

Waste Burning ◽

Indo Gangetic Plain ◽

Mass Concentrations

We compare the mass concentrations of black carbon (BC) and elemental carbon (EC) from different emissions in the Indo-Gangetic Plain (IGP), using optical (Aethalometer; 880 nm) and thermooptical technique (EC-OC analyzer; 678 nm), respectively. The fractional contribution of BC mass concentration measured at two different channels (370 and 880 nm), OC/EC ratio, and non-sea-salt K+/EC ratios have been systematically monitored for representing the source characteristics of BC and EC in this study. The mass concentrations of BC varied from 8.5 to 19.6, 2.4 to 18.2, and 2.2 to 9.4 μg m−3during October-November (paddy-residue burning emission), December–March (emission from bio- and fossil-fuel combustion) and April-May (wheat-residue burning emission), respectively. In contrast, the mass concentrations of EC varied from 3.8 to 17.5, 2.3 to 8.9, and 2.0 to 8.8 μg m−3during these emissions, respectively. The BC/EC ratios conspicuously greater than 1.0 have been observed during paddy-residue burning emissions associated with high mass concentrations of EC, OC, and OC/EC ratio. The Ångström exponent (α) derived from Aethalometer data is approximately 1.5 for the postharvest agricultural-waste burning emissions, hitherto unknown for the IGP. The mass absorption efficiency (MAE) of BC and EC centers at ~1–4 m2 g−1and 2-3 m2 g−1during the entire study period in the IGP.

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Black carbon aerosol mass concentrations over Ahmedabad, an urban location in western India: Comparison with urban sites in Asia, Europe, Canada, and the United States

Journal of Geophysical Research Atmospheres ◽

10.1029/2006jd007488 ◽

2007 ◽

Vol 112 (D6) ◽

Cited By ~ 115

Author(s):

S. Ramachandran ◽

T. A. Rajesh

Keyword(s):

United States ◽

Black Carbon ◽

The United States ◽

Western India ◽

Urban Location ◽

Aerosol Mass ◽

Black Carbon Aerosol ◽

Urban Sites ◽

Mass Concentrations

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On the frequency of the 2015 monsoon season drought in the Indo-Gangetic Plain

Geophysical Research Letters ◽

10.1002/2016gl071407 ◽

2016 ◽

Vol 43 (23) ◽

pp. 12,102-12,112 ◽

Cited By ~ 32

Author(s):

Vimal Mishra ◽

Saran Aadhar ◽

Akarsh Asoka ◽

Sivananda Pai ◽

Rohini Kumar

Keyword(s):

Monsoon Season ◽

Gangetic Plain ◽

Indo Gangetic Plain

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Wintertime direct radiative effects due to black carbon (BC) over the Indo-Gangetic Plain as modelled with new BC emission inventories in CHIMERE

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-7671-2021 ◽

2021 ◽

Vol 21 (10) ◽

pp. 7671-7694

Author(s):

Sanhita Ghosh ◽

Shubha Verma ◽

Jayanarayanan Kuttippurath ◽

Laurent Menut

Keyword(s):

Black Carbon ◽

Transport Model ◽

Eastern Coast ◽

Emission Inventories ◽

Surface Cooling ◽

Gangetic Plain ◽

Bottom Up ◽

Bc Aerosols ◽

Radiative Perturbation ◽

Indo Gangetic Plain

Abstract. To reduce the uncertainty in climatic impacts induced by black carbon (BC) from global and regional aerosol–climate model simulations, it is a foremost requirement to improve the prediction of modelled BC distribution, specifically over the regions where the atmosphere is loaded with a large amount of BC, e.g. the Indo-Gangetic Plain (IGP) in the Indian subcontinent. Here we examine the wintertime direct radiative perturbation due to BC with an efficiently modelled BC distribution over the IGP in a high-resolution (0.1∘ × 0.1∘) chemical transport model, CHIMERE, implementing new BC emission inventories. The model efficiency in simulating the observed BC distribution was assessed by executing five simulations: Constrained and bottomup (bottomup includes Smog, Cmip, Edgar, and Pku). These simulations respectively implement the recently estimated India-based observationally constrained BC emissions (Constrainedemiss) and the latest bottom-up BC emissions (India-based: Smog-India; global: Coupled Model Intercomparison Project phase 6 – CMIP6, Emission Database for Global Atmospheric Research-V4 – EDGAR-V4, and Peking University BC Inventory – PKU). The mean BC emission flux from the five BC emission inventory databases was found to be considerably high (450–1000 kg km−2 yr−1) over most of the IGP, with this being the highest (> 2500 kg km−2 yr−1) over megacities (Kolkata and Delhi). A low estimated value of the normalised mean bias (NMB) and root mean square error (RMSE) from the Constrained estimated BC concentration (NMB: < 17 %) and aerosol optical depth due to BC (BC-AOD) (NMB: 11 %) indicated that simulations with Constrainedemiss BC emissions in CHIMERE could simulate the distribution of BC pollution over the IGP more efficiently than with bottom-up emissions. The high BC pollution covering the IGP region comprised a wintertime all-day (daytime) mean BC concentration and BC-AOD respectively in the range 14–25 µg m−3 (6–8 µg m−3) and 0.04–0.08 µg m−3 from the Constrained simulation. The simulated BC concentration and BC-AOD were inferred to be primarily sensitive to the change in BC emission strength over most of the IGP (including the megacity of Kolkata), but also to the transport of BC aerosols over megacity Delhi. Five main hotspot locations were identified in and around Delhi (northern IGP), Prayagraj–Allahabad–Varanasi (central IGP), Patna–Palamu (upper, lower, and mideastern IGP), and Kolkata (eastern IGP). The wintertime direct radiative perturbation due to BC aerosols from the Constrained simulation estimated the atmospheric radiative warming (+30 to +50 W m−2) to be about 50 %–70 % larger than the surface cooling. A widespread enhancement in atmospheric radiative warming due to BC by 2–3 times and a reduction in surface cooling by 10 %–20 %, with net warming at the top of the atmosphere (TOA) of 10–15 W m−2, were noticed compared to the atmosphere without BC, for which a net cooling at the TOA was exhibited. These perturbations were the strongest around megacities (Kolkata and Delhi), extended to the eastern coast, and were inferred to be 30 %–50% lower from the bottomup than the Constrained simulation.

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Black carbon variability since preindustrial times in Eastern part of Europe reconstructed from Mt Elbrus, Caucasus ice cores

10.5194/acp-2016-804 ◽

2016 ◽

Author(s):

Saehee Lim ◽

Xavier Faïn ◽

Patrick Ginot ◽

Vladimir Mikhalenko ◽

Stanislav Kutuzov ◽

...

Keyword(s):

Black Carbon ◽

20Th Century ◽

Biomass Burning ◽

Mass Concentration ◽

Ice Core ◽

Ice Cores ◽

Anthropogenic Emissions ◽

Ice Core Record ◽

Summer Time ◽

Mass Concentrations

Abstract. Black carbon (BC), emitted by fossil fuel combustion and biomass burning, is the second largest man-made contributor to global warming after carbon dioxide (Bond et al., 2013). However, limited information exists on its past emissions and atmospheric variability. In this study, we present the first high-resolution record of refractory BC (rBC, including mass concentration and size) reconstructed from ice cores drilled at a high-altitude Eastern European site in Mt. Elbrus (ELB), Caucasus (5115 m a.s.l.). The ELB ice core record, covering the period 1825–2013, reflects the atmospheric load of rBC particles at the ELB site transported from the European continent with a larger rBC input from sources located in the Eastern part of Europe. In the first half of the 20th century, European anthropogenic emissions resulted in a 1.5-fold increase in the ice core rBC mass concentrations as respect to its level in the preindustrial era (before 1850). The rBC mass concentrations increased by a 5-fold in 1960–1980, followed by a decrease until ~ 2000. Over the last decade, the rBC signal for summer time slightly increased. We have compared the signal with the atmospheric BC load simulated using past BC emissions (ACCMIP and MACCity inventories) and taken into account the contribution of different geographical region to rBC distribution and deposition at the ELB site. Interestingly, the observed rBC variability in the ELB ice core record since the 1960s is not in perfect agreement with the simulated atmospheric BC load. Similar features between the ice core rBC record and the best scenarios for the atmospheric BC load support that anthropogenic BC increase in the 20th century is reflected in the ELB ice core record. However, the peak in BC mass concentration observed in ~ 1970 in the ice core is estimated to occur a decade later from past inventories. BC emission inventories for the period 1960s–1970s may be underestimating European anthropogenic emissions. Furthermore, for summer time snow layers of the last 2000s, the slightly increasing trend of rBC deposition likely reflects recent changes in anthropogenic and biomass burning BC emissions in the Eastern part of Europe. Our study highlights that the past changes in BC emissions of Eastern Europe need to be considered in assessing on-going air quality regulation.

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Black Carbon physical and optical properties across northern India during pre-monsoon and monsoon seasons

10.5194/acp-2019-505 ◽

2019 ◽

Author(s):

James Brooks ◽

Dantong Liu ◽

James D. Allan ◽

Paul I. Williams ◽

Jim Haywood ◽

...

Keyword(s):

Physical Properties ◽

Black Carbon ◽

Mixing State ◽

Atmospheric Measurements ◽

Core Diameter ◽

Gangetic Plain ◽

North West ◽

North East ◽

Northern India ◽

Indo Gangetic Plain

Abstract. Black carbon (BC) is known to have major impacts on both climate and human health, so is therefore of global importance, particularly so in regions close to large populations that have strong sources. The physical properties and mixing state of black carbon containing particles are important determinants in these effects but information is often lacking, particularly in some of the most important regions of the globe. Detailed analysis into the vertical and horizontal BC optical and physical properties across northern India has been carried out using airborne in-situ measurements. The size-resolved mixing state of BC-containing particles was characterised using a single particle soot photometer (SP2). The study focusses on the Indo-Gangetic Plain during the pre-monsoon and monsoon seasons. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights during the pre-monsoon (11th and 12th June) and monsoon (30th June to 11th July) seasons of 2016. Over the Indo-Gangetic Plain, BC mass concentrations were greater (1.95 µg/m3) compared to north-west India (1.50 µg/m3) and north-east India (0.70 µg/m3) during the pre-monsoon. Across northern India, two distinct BC modes were recorded; a mode of small BC particles (core diameter

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Spatial, temporal and source contribution assessments of BC over the northern interior of South Africa

10.5194/acp-2016-934 ◽

2016 ◽

Author(s):

Kgaugelo Euphinia Chiloane ◽

Johan Paul Beukes ◽

Pieter Gideon van Zyl ◽

Petra Maritz ◽

Ville Vakkari ◽

...

Keyword(s):

South Africa ◽

Black Carbon ◽

Southern Africa ◽

Mass Concentration ◽

Source Region ◽

Measurement Data ◽

Concentration Data ◽

Power Stations ◽

Concentration Levels ◽

Mass Concentrations

Abstract. After carbon dioxide (CO2), aerosol black carbon (BC) is considered to be the second most important contributor to global warming. Africa is one of the least studied continents, although it is regarded as the largest source region of atmospheric BC. Southern Africa is an important sub-source region, with savannah and grassland fires likely to contribute to elevated BC mass concentration levels. South Africa is the economic and industrial hub of southern Africa. To date, little BC mass concentration data have been presented for South Africa in the peer-reviewed public domain. This paper presents equivalent black carbon (eBC) (derived from an optical absorption method) data collected from three sites, where continuous measurements have been conducted, i.e. Elandsfontein (EL), Welgegund (WG) and Marikana (MA), as well elemental carbon (EC) (determined by evolved carbon method) at five sites where samples were collected once a month on a filter and analysed off-line, i.e. Louis Trichardt (LT), Skukuza (SK), Vaal Triangle (VT), Amersfoort (AM) and Botsalano (BS). All these sites are located in the interior of South Africa. Analyses of eBC and EC spatial mass concentration patterns across the eight sites indicate that the mass concentrations in the South African interior are in general higher than what has been reported for the developed world and that different sources are likely to influence different sites. The mean eBC or EC mass concentrations for the background sites (WG, LT, SK, BS) and sites influenced by industrial activities and/or nearby settlements (EL, MA, VT and AM) ranged between 0.7 and 1.1, and 1.3 and 1.4 µg/m3, respectively. Similar seasonal patterns were observed at all three sites where continuous measurement data were collected (EL, MA and WG), with the highest eBC mass concentrations measured during June to October, indicating contributions from household combustion in the cold winter months (June–August), as well as savannah and grassland fires during the dry season (May to mid-October). Diurnal patterns of eBC at EL, MA and WG indicated maximum concentrations in the early mornings and late evenings, and minima during daytime. From the patterns it could be deduced that for MA and WG, household combustion and savannah, and grassland fires were the most significant sources, respectively. Possible contributing sources were explored in greater detail for EL, with five main sources being identified as coal-fired power stations, pyrometallurgical smelters, traffic, household combustion, as well as savannah and grassland fires. Industries on the Mpumalanga Highveld are often blamed for all forms of pollution, due to the NO2 hotspot over this area that is attributed to NOx emissions from industries and vehicle emissions from the Johannesburg-Pretoria megacity. However, a comparison of source strengths indicated that household combustion, and savannah and grassland fires were the most significant sources of eBC, particularly during winter and spring months, while coal-fired power stations, pyro-metallurgical smelters and traffic contribute to eBC mass concentration levels year round.

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