Effect of COVID-19 shutdown on aerosol direct radiative forcing over the Indo-Gangetic Plain outflow region of the Bay of Bengal

During Diwali festival, extensive burning of crackers and fireworks is made. Weeklong intensive observational campaign for aerosol study was carried out at a representative urban location in the eastern Indo-Gangetic Plain (IGP), Varanasi (25.3°N, 83.0°E), from October 29 to November 04, 2005 (Diwali on November 01, 2005), to investigate behavioral change of aerosol properties and radiative forcing between firework affected and nonaffected periods. Results show a substantial increase (~27%) in aerosol optical depth, aerosol absorption coefficients, and aerosol scattering coefficients during affected period as compared to non-affected periods. Magnitudes of radiative forcing at top of atmosphere during affected and non-affected periods are found to be +10 ± 1 and +12 ± 1 Wm−2, respectively, which are −31 ± 7 and −17 ± 5 Wm−2, respectively, at surface. It suggests an additional cooling of ~20% at top of atmosphere, ~45% cooling at surface, and additional atmospheric heating of 0.23 Kday−1during fireworks affected period, which is ~30% higher than the non-affected period average.

Download Full-text

Development of a Regression Model for Estimating Daily Radiative Forcing Due to Atmospheric Aerosols from Moderate Resolution Imaging Spectrometers (MODIS) Data in the Indo Gangetic Plain (IGP)

Atmosphere ◽

10.3390/atmos9100405 ◽

2018 ◽

Vol 9 (10) ◽

pp. 405 ◽

Cited By ~ 1

Author(s):

Shreemat Shrestha ◽

Murray Peel ◽

Graham Moore

Keyword(s):

Regression Model ◽

Water Vapour ◽

Atmospheric Aerosols ◽

Radiative Forcing ◽

Crop Production ◽

Atmospheric Water ◽

Gangetic Plain ◽

Atmospheric Water Vapour ◽

Station Data ◽

Indo Gangetic Plain

The assessment of direct radiative forcing due to atmospheric aerosols (ADRF) in the Indo Gangetic Plain (IGP), which is a food basket of south Asia, is important for measuring the effect of atmospheric aerosols on the terrestrial ecosystem and for assessing the effect of aerosols on crop production in the region. Existing comprehensive analytical models to estimate ADRF require a large number of input parameters and high processing time. In this context, here, we develop a simple model to estimate daily ADRF at any location on the surface of the IGP through multiple regressions of AErosol RObotic NETwork (AERONET) aerosol optical depth (AOD) and atmospheric water vapour using data from 2002 to 2015 at 10 stations in the IGP. The goodness of fit of the model is indicated by an adjusted R2 value of 0.834. The Jackknife method of deleting one group (station data) was employed to cross validate and study the stability of the regression model. It was found to be robust with an adjusted R2 fluctuating between 0.813 and 0.842. In order to use the year-round ADRF model for locations beyond the AERONET stations in the IGP, AOD, and atmospheric water vapour products from MODIS Aqua and Terra were compared against AERONET station data and they were found to be similar. Using MODIS Aqua and Terra products as input, the year-round ADRF regression was evaluated at the IGP AERONET stations and found to perform well with Pearson correlation coefficients of 0.66 and 0.65, respectively. Using ADRF regression model with MODIS inputs allows for the estimation of ADRF across the IGP for assessing the aerosol impact on ecosystem and crop production.

Download Full-text

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-17669-2018 ◽

2018 ◽

Vol 18 (23) ◽

pp. 17669-17685 ◽

Cited By ~ 16

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.

Download Full-text

Absorbing Refractive Index and Direct Radiative Forcing of Atmospheric Brown Carbon over Gangetic Plain

ACS Earth and Space Chemistry ◽

10.1021/acsearthspacechem.7b00074 ◽

2017 ◽

Vol 2 (1) ◽

pp. 31-37 ◽

Cited By ~ 14

Author(s):

P. M. Shamjad ◽

R. V. Satish ◽

Navaneeth M. Thamban ◽

N. Rastogi ◽

S. N. Tripathi

Keyword(s):

Refractive Index ◽

Radiative Forcing ◽

Gangetic Plain ◽

Brown Carbon ◽

Direct Radiative Forcing

Download Full-text

Assessment of Indoor & Outdoor Black Carbon emissions in rural areas of Indo-Gangetic Plain: seasonal characteristics, source apportionment and radiative forcing

Atmospheric Environment ◽

10.1016/j.atmosenv.2018.07.057 ◽

2018 ◽

Vol 191 ◽

pp. 227-240 ◽

Cited By ~ 2

Author(s):

Mohammad Arif ◽

Rajesh Kumar ◽

Ramesh Kumar ◽

Eric Zusman ◽

Ramesh P. Singh ◽

...

Keyword(s):

Black Carbon ◽

Source Apportionment ◽

Carbon Emissions ◽

Rural Areas ◽

Radiative Forcing ◽

Gangetic Plain ◽

Seasonal Characteristics ◽

Indo Gangetic Plain

Download Full-text

The mixing state of aerosols over the Indo-Gangetic Plain and its impact on radiative forcing

Quarterly Journal of the Royal Meteorological Society ◽

10.1002/qj.1958 ◽

2012 ◽

Vol 139 (670) ◽

pp. 137-151 ◽

Cited By ~ 44

Author(s):

Rohit Srivastava ◽

S. Ramachandran

Keyword(s):

Radiative Forcing ◽

Mixing State ◽

Gangetic Plain ◽

Indo Gangetic Plain

Download Full-text

Aerosol chemistry, transport and climatic implications during extreme biomass burning emissions over Indo-Gangetic Plain

10.5194/acp-2018-446 ◽

2018 ◽

Author(s):

Nandita Singh ◽

Tirthankar Banerjee ◽

Made P. Raju ◽

Karine Deboudt ◽

Meytar Sorek-Hamer ◽

...

Keyword(s):

Biomass Burning ◽

Radiative Forcing ◽

Large Scale ◽

Regional Climate ◽

Water Soluble ◽

Submicron Particles ◽

Aerosol Layer ◽

Sudden Increase ◽

Gangetic Plain ◽

Indo Gangetic Plain

Abstract. The large-scale emissions of airborne particulates from burning of agricultural residues particularly over the upper Indo-Gangetic Plain (IGP) have often been associated with frequent formation of haze, adverse health impacts, modification in aerosol climatology and thereby aerosols impact on regional climate. In this study, short-term variations in aerosol climatology during extreme biomass burning emissions over IGP, and thereby to regional climate were investigated. Size-segregated particulate concentration was initially measured and submicron particles (PM1.1) were found to dominate particulate mass within the fine mode (PM2.1). Particulate bound water-soluble ions were mainly secondary in nature, primarily composed of sulfate and nitrate. There was evidence of gaseous NH3 dominating neutralization of acidic aerosol species (SO42−) in submicron particles, in contrast to crustal dominating neutralization in coarser particulates. Variation in black carbon mass ratio was found to be influenced by local sources, while sudden increase in concentration was consistent with high Delta-C, referring to biogenic emissions. Influence of biomass burning emissions were established using specific organic (levoglucosan), inorganic (K+ and NH4+) and satellite (UV Aerosol Index, UVAI) tracers. Levoglucosan was the most abundant within submicron particles (649±177 ng m−3), with a very high ratio (>50) against other anhydrosugars, indicating exclusive emissions from burning of agriculture residues. Temporal variations of all the tracers were consistent, while NH4+ was more closely associated to levoglucosan. Spatio-temporal distribution of aerosol and few trace gases (CO and NO2) were evaluated using both space-borne active and passive sensors, and a significant increase in columnar aerosol loading (AOD: 0.98) was evident during extreme biomass burning emissions, with presence of absorbing aerosols (UVAI > 1.5) having low aerosol layer height (~1.5 km). A strong intraseasonality in aerosol cross-sectional altitudinal profile was even noted from CALIPSO, referring dominance of smoke and polluted continental aerosols across IGP. Possible transport mechanism of biomass smoke was established using cluster analysis and concentration weighted of air mass back-trajectories. Short-wave aerosol radiative forcing (ARF) was further simulated considering intraseasonality in aerosol properties, which resulted in considerable increase of atmospheric ARF (135 Wm−2) and heating rate (4.3 K day−1) during extreme biomass burning emissions compared to non-dominating one (56 Wm−2, 1.8 K day−1). We therefore conclude that influence of biomass burning emissions on regional aerosol climatology must need to be studied in much finer scale to improve parameterization of aerosol/-climate model across the region.

Download Full-text