Optical properties of aerosol brown carbon (BrC) in the eastern Indo-Gangetic Plain

2020 ◽  
Vol 716 ◽  
pp. 137102 ◽  
Author(s):  
Archita Rana ◽  
Supriya Dey ◽  
Prashant Rawat ◽  
Arya Mukherjee ◽  
Jingying Mao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Indo Gangetic Plain

Brown carbon in the continental outflow to the North Indian Ocean

2019 ◽  
Vol 21 (6) ◽  
pp. 970-987 ◽  
Author(s):  
Srinivas Bikkina ◽  
Manmohan Sarin
Keyword(s):  
Indian Ocean ◽  
Soluble Fraction ◽  
North Indian Ocean ◽  
Water Soluble ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Water Soluble Fraction ◽  
The North ◽  
Continental Outflow ◽  
Indo Gangetic Plain

In this paper, we synthesize the size distribution and optical properties of the atmospheric water-soluble fraction of light-absorbing organic carbon (brown carbon; BrC) in the continental outflow from the Indo-Gangetic Plain (IGP) in South Asia to the North Indian Ocean.

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.

scholarly journals Direct radiative effect by brown carbon over the Indo-Gangetic Plain

2015 ◽  
Vol 15 (22) ◽  
pp. 12731-12740 ◽  
Author(s):  
A. Arola ◽  
G. L. Schuster ◽  
M. R. A. Pitkänen ◽  
O. Dubovik ◽  
H. Kokkola ◽  
...  
Keyword(s):  
Winter Season ◽  
Carbonaceous Aerosols ◽  
Radiative Effect ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Relative Significance ◽  
Aerosol Absorption ◽  
Spectrally Resolved ◽  
First Time ◽  
Indo Gangetic Plain

Abstract. The importance of light-absorbing organic aerosols, often called brown carbon (BrC), has become evident in recent years. However, there have been relatively few measurement-based estimates for the direct radiative effect of BrC so far. In earlier studies, the AErosol RObotic NETwork (AERONET)-measured aerosol absorption optical depth (AAOD) and absorption Angstrom exponent (AAE) were exploited. However, these two pieces of information are clearly not sufficient to separate properly carbonaceous aerosols from dust, while imaginary indices of refraction would contain more and better justified information for this purpose. This is first time that the direct radiative effect (DRE) of BrC is estimated by exploiting the AERONET-retrieved imaginary indices. We estimated it for four sites in the Indo-Gangetic Plain (IGP), Karachi, Lahore, Kanpur and Gandhi College. We found a distinct seasonality, which was generally similar among all the sites, but with slightly different strengths. The monthly warming effect up to 0.5 W m−2 takes place during the spring season. On the other hand, BrC results in an overall cooling effect in the winter season, which can reach levels close to −1 W m−2. We then estimated similarly also the DRE of black carbon and total aerosol, in order to assess the relative significance of the BrC radiative effect in the radiative effects of other components. Even though BrC impact seems minor in this context, we demonstrated that it is not insignificant. Moreover, we demonstrated that it is crucial to perform spectrally resolved radiative transfer calculations to obtain good estimates for the DRE of BrC.

Brown carbon aerosols in the Indo-Gangetic Plain outflow: insights from excitation emission matrix (EEM) fluorescence spectroscopy

2021 ◽  
Author(s):  
Supriya Dey ◽  
Arya Mukherjee ◽  
Anuraag J Polana ◽  
Archita Rana ◽  
Jingying Mao ◽  
...  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Excitation Emission Matrix ◽  
Indian Context ◽  
Parallel Factor ◽  
Carbon Aerosols ◽  
Indo Gangetic Plain ◽  
Eem Fluorescence

We report the first characterization of aerosol brown carbon (BrC) composition in the Indian context using excitation emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor (PARAFAC) analysis. We find...

Optical properties of atmospheric brown carbon (BrC) for photochemical and biomass burning-dominated aerosol regimes in India.

2020 ◽  
Author(s):  
Archita Rana ◽  
Supriya Dey ◽  
Sayantan Sarkar
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Global Climate ◽  
Strong Association ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
Tropospheric Chemistry ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Fluorescence Measurements

<p>Black and brown carbon (BC and BrC) are potent climate forcing agents with pronounced effects on global climate and tropospheric chemistry. Given the large heterogeneities in BC emission inventories from India and the paucity of studies on BrC characteristics, field-based measurements of BC and BrC sources and optical properties are essential to understand their impacts on regional climate. To address this issue, we report the first ground-based measurements of BC and BrC from a rural location in the highly polluted eastern Indo-Gangetic Plain (IGP) during May-November 2018 encompassing the photochemistry-dominated summer (May-June) and regional biomass burning (BB)-dominated post-monsoon (October-November) periods. A 7-wavelength Aethalometer was used for time-resolved measurements of BC mass and was supplemented by UV-Vis and fluorescence measurements of time-integrated (24 h) aqueous and organic BrC fractions, and measurements of OC, EC, WSOC, and ionic species.<br>The daily averaged BC increased 4 times during the BB regime (12.3 ± 3.9 μg m<sup>-3</sup>) as compared to summer (4.2 ± 0.8 μg m<sup>-3</sup>), while aqueous and organic BrC fractions demonstrated light absorption (babs_365) enhancements of 3-5 times during BB. For aqueous BrC, the averaged AE of 5.9-6.2 and a prominent fluorescence peak at ~420 nm suggested the presence of humic-like substances (HULIS), potentially from secondary photochemical formation during summer and primary emission during BB periods. Fluorescence and UV-Vis spectra also indicated the presence of nitroaromatic compounds, presumably from OH oxidation in summer and nighttime NO3- oxidation in the presence of enhanced NOx and precursor emission during BB. The latter was supported by the strong association between water-soluble organic carbon (WSOC; a proxy for aqueous BrC) and aerosol NO<sub>3</sub><sup>-</sup> (r=0.70, p<0.05). During BB, the fraction of water-insoluble (i.e., organic) BrC increased from 41% at 330 nm to 59 % at 550 nm while during the photochemistry-dominated summer period, the water-insoluble BrC fraction decreased from 73% at 400 nm to 41% at 530 nm, possibly due to photobleaching in the presence of OH. The BB-related BrC aerosol was also characterized by higher aromaticity and increased molecular weights of organic components as evidenced by mass absorption efficiency (MAE) ratios (MAE<sub>250</sub>/MAE<sub>365</sub>). Overall, this study established that BrC is a significant component of light-absorbing aerosol in the eastern IGP and that BrC optical properties may vary significantly in this region depending on the relative dominance of aerosol emissions and atmospheric processes.</p>

Light absorption characteristics of brown carbon during foggy and non-foggy episodes over the Indo-Gangetic Plain

2018 ◽  
Vol 9 (3) ◽  
pp. 494-501 ◽  
Author(s):  
Vikram Choudhary ◽  
Prashant Rajput ◽  
Dharmendra Kumar Singh ◽  
Amit Kumar Singh ◽  
Tarun Gupta
Keyword(s):  
Light Absorption ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Indo Gangetic Plain ◽  
Absorption Characteristics
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