Investigating the relative responses of regional monsoon dynamics to snow darkening and direct radiative effects of dust and carbonaceous aerosols over the Indian subcontinent

2020 ◽  
Vol 55 (3-4) ◽  
pp. 1011-1030 ◽  
Author(s):  
Sushant Das ◽  
Filippo Giorgi ◽  
Graziano Giuliani
Keyword(s):  
Indian Subcontinent ◽  
Carbonaceous Aerosols ◽  
Radiative Effects ◽  
Monsoon Dynamics ◽  
Regional Monsoon

scholarly journals Characteristics, seasonality and sources of carbonaceous and ionic components in the tropical Indian aerosols

2011 ◽  
Vol 11 (2) ◽  
pp. 3937-3976 ◽  
Author(s):  
C. M. Pavuluri ◽  
K. Kawamura ◽  
S. G. Aggarwal ◽  
T. Swaminathan
Keyword(s):  
Organic Carbon ◽  
Atmospheric Aerosols ◽  
Atmospheric Transport ◽  
Indian Subcontinent ◽  
Ionic Species ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Mass Fractions ◽  
High Concentrations ◽  
Ionic Components

Abstract. To better characterize South and Southeast Asian aerosols, PM10 samples collected from tropical Chennai, India (13.04° N; 80.17° E) were analyzed for carbonaceous and water-soluble ionic components. Concentration ranges of elemental carbon (EC) and organic carbon (OC) were 2.4–14 μg m−3 and 3.2–15.6 μg m−3 in winter samples whereas they were 1.1–2.5 μg m−3 and 4.1–17.6 μg m−3 in summer samples, respectively. Concentration of secondary organic carbon (SOC) retrieved from EC-tracer method was 4.6 ± 2.8 μg m−3 in winter and 4.3 ± 2.8 μg m−3 in summer. SO42- (8.8 ± 2.5 μg m−3 and 4.1 ± 2.7 μg m−3 in winter and summer, respectively) was found as the most abundant ionic species (57% on average, n = 49), followed by NH4+ (15%) > NO3− > Cl− > K+> Na+ > Ca2+ > MSA− > Mg2+. The mass fractions of EC, organic matter (OM) and ionic species varied seasonally, following the air mass trajectories and corresponding source strength. Based on mass concentration ratios of selected components and relations of EC and OC to marker species, we found that biofuel/biomass burning is the major source of atmospheric aerosols in South and Southeast Asia. The high concentrations of SOC and WSOC/OC ratios (ave. 0.45; n = 49) as well as good correlations between SOC and WSOC suggest that the secondary production of organic aerosols during long-range atmospheric transport is also significant in this region. This study provides the baseline data of carbonaceous aerosols for southern part of the Indian subcontinent.

scholarly journals Submicron particles influenced by mixed biogenic and anthropogenic emissions: high-resolution aerosol mass spectrometry results from the Carbonaceous Aerosols and Radiative Effects Study (CARES)

2012 ◽  
Vol 12 (2) ◽  
pp. 5601-5658 ◽  
Author(s):  
A. Setyan ◽  
Q. Zhang ◽  
M. Merkel ◽  
W. B. Knighton ◽  
Y. Sun ◽  
...  
Keyword(s):  
High Resolution ◽  
Submicron Particles ◽  
Biogenic Emissions ◽  
Anthropogenic Emissions ◽  
Carbonaceous Aerosols ◽  
Mass Loading ◽  
Radiative Effects ◽  
Large Variability ◽  
Aerosol Mass ◽  
Urban Plumes

Abstract. The Carbonaceous Aerosols and Radiative Effects Study (CARES) took place in the Sacramento Valley of California in summer 2010. We present results obtained at Cool, CA, the T1 site of the project (~40 km downwind of urban emissions from Sacramento), where we deployed an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) in parallel with complementary instrumentation to characterize the sources and processes of submicron particles (PM1). Cool is located at the foothill of the Sierra Nevada Mountains, where intense biogenic emissions are periodically mixed with urban outflow transported by daytime southwesterly winds from the Sacramento metropolitan area. The particle mass loading was low (3.0 μg m−3 on average) and dominated by organics (80 % of the PM1 mass) followed by sulfate (9.9 %). Organics and sulfate appeared to be externally mixed, as suggested by their different time series (r2 = 0.13) and size distributions. Sulfate showed a bimodal distribution with a droplet mode peaking at $\\sim400$ nm in vacuum aerodynamic diameter (Dva), and a condensation mode at ~150 nm, while organics generally displayed a broad distribution in 60–600 nm (Dva). New particle formation and growth events were observed almost every day, emphasizing the roles of organics and sulfate in new particle growth, especially that of organics. The organic aerosol (OA) had a~nominal formula of C1H1.38N0.004O0.44, thus an average organic mass-to-carbon (OM/OC) ratio of 1.70. Two different oxygenated OA (OOA, 90 % of total OA mass) and a hydrocarbon-like OA (HOA, 10 %) were identified by Positive matrix factorization (PMF) of the high-resolution mass spectra. The more oxidized MO-OOA (O/C = 0.54) corresponded to secondary OA (SOA) primarily influenced by biogenic emissions, while the less oxidized LO-OOA (O/C = 0.42) corresponded to SOA associated with urban transport. The HOA factor corresponded to primary emissions mainly due to local traffic. Twenty three periods of urban plumes from T0 (Sacramento) to T1 (Cool) were identified using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). The average PM1 mass loading was much higher in urban plumes (3.9 μg m−3) than in air masses dominated by biogenic SOA (1.8 μg m−3). The change in OA mass relative to CO (Δ OA/Δ CO) varied in the range of 5–196 μg m−3 ppm−1, reflecting large variability in SOA production. The highest Δ OA/Δ CO were reached when urban plumes arrived at Cool in the presence of a~high concentration of biogenic volatile organic compounds (BVOCs = isoprene + monoterpenes + 2-methyl-3-buten-2-ol [MBO] + methyl chavicol). This ratio, which was 77 μg m−3 ppm−1 on average when BVOCs > 2 ppb, is much higher than when urban plumes arrived in a low biogenic VOCs environment (28 μg m−3 ppm−1 when BVOCs < 0.7 ppb) or during other periods dominated by biogenic SOA (40 μg m−3 ppm−1). The results from this study demonstrate that SOA formation is enhanced when anthropogenic emissions interact with biogenic precursors.

scholarly journals Characteristics, seasonality and sources of carbonaceous and ionic components in the tropical aerosols from Indian region

2011 ◽  
Vol 11 (15) ◽  
pp. 8215-8230 ◽  
Author(s):  
C. M. Pavuluri ◽  
K. Kawamura ◽  
S. G. Aggarwal ◽  
T. Swaminathan
Keyword(s):  
Organic Carbon ◽  
Atmospheric Aerosols ◽  
Atmospheric Transport ◽  
Indian Subcontinent ◽  
Ionic Species ◽  
Water Soluble ◽  
Indian Region ◽  
Carbonaceous Aerosols ◽  
High Concentrations ◽  
Ionic Components

Abstract. To better characterize the tropical aerosols in Indian region, PM10 samples collected from Chennai, India (13.04° N; 80.17° E) were analyzed for carbonaceous and water-soluble ionic components. Concentration ranges of elemental carbon (EC) and organic carbon (OC) were 2.4–14 μg m−3 (ave. 6.5 μg m−3) and 3.2–15.6 μg m−3 (ave. 9.1 μg m−3) in winter samples whereas they were 1.1–2.5 μg m−3 (ave. 1.6 μg m−3) and 4.1–17.6 μg m−3 (ave. 9.7 μg m−3) in summer samples, respectively. Concentration of secondary organic carbon (SOC) retrieved from EC-tracer method was 4.6±2.8 μg m−3 in winter and 4.3±2.8 μg m−3 in summer. OC accounted for 38.5±14 % (n = 49) of combined concentrations of carbonaceous and ionic components in PM10. We also found that OC concentrations are generally higher than those of SO42− (8.8±2.5 μg m−3 and 4.1±2.7 μg m−3 in winter and summer, respectively), which was the most abundant ionic species (57 %) followed by NH4+ (15 %) >NO3−>Cl−>K+>Na+> Ca2+>MSA−>Mg2+. The mass fractions of EC, organic matter (OM) and ionic species varied seasonally, following the air mass trajectories and corresponding source strength. Based on mass concentration ratios of selected components and relations of EC and OC to marker species, we found that biofuel/biomass burning is a major source of atmospheric aerosols in South and Southeast Asia. The high concentrations of SOC and WSOC/OC ratios (ave. 0.45; n = 49) as well as good correlations between SOC and WSOC suggest that the secondary production of organic aerosols during long-range atmospheric transport is also significant in this region. This study provides the baseline data of carbonaceous aerosols for southern part of the Indian subcontinent.

scholarly journals Assessment of Regional Aerosol Radiative Effects under SWAAMI Campaign – Part 1: Quality-enhanced Estimation of Columnar Aerosol Extinction and Absorption Over the Indian Subcontinent

2019 ◽  
Author(s):  
Harshavardhana Sunil Pathak ◽  
Sreedharan Krishnakumari Satheesh ◽  
Ravi Shankar Nanjundiah ◽  
Krishnaswamy Krishna Moorthy ◽  
Sivaramakrishnan Lakshmivarahan ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Large Scale ◽  
Indian Subcontinent ◽  
Indian Region ◽  
The South ◽  
Radiative Effects ◽  
Spatial Coverage ◽  
Spatially Homogeneous ◽  
Aerosol Radiative Effects ◽  
Aerosol Radiative

Abstract. Improving the accuracy of regional aerosol climate impact assessment calls for an improvement in the accuracy of regional aerosol radiative effects (ARE) estimation. One of the most important means of achieving this is to use spatially homogeneous and temporally continuous datasets of critical aerosol properties, such as spectral aerosol optical depth (AOD) and single scattering albedo (SSA), which are the most important parameters for estimating aerosol radiative effects. However, observations do not provide the above; the space-borne observations though provide wide spatial coverage, are temporally snapshots and suffer from possible sensor degradation over extended periods. On the other hand, the ground-based measurements provide more accurate and temporally continuous data, but are spatially near-point observations. Realizing the need for spatially homogeneous and temporally continuous datasets on one hand and the near-non-existence of such data over the south Asian region (which is one of the regions where aerosols show large heterogeneity in most of their properties), construction of accurate gridded aerosol products by synthesizing the long-term space-borne and ground-based data, has been taken up as an important objective of the South West Asian Aerosol Monsoon Interactions (SWAAMI), a joint Indo-UK field campaign, aiming at characterizing aerosol-monsoon links and their variabilities over the Indian region. In the Part-1 of this two-part paper, we present spatially homogeneous gridded datasets of AOD and absorption AOD (AAOD), generated for the first time over this region. These data products are developed by merging the highly accurate aerosol measurements from the dense networks of 44 (for AOD) and 34 (for AAOD) ground-based observatories of Aerosol Radiative Forcing NETwork (ARFINET) and AErosol RObotic NETwork (AERONET) spread across the Indian region, with satellite-retrieved AOD and AAOD, following statistical assimilation schemes. The satellite data used for AOD assimilation includes AODs retrieved from MODerate Imaging Spectroradiometer (MODIS) and Multiangle Imaging SpectroRadiometer (MISR) over the same domain. For AAOD, the ground-based Black Carbon (BC) mass concentration measurements from the network of 34 ARFINET observatories and satellite-based (Kalpana-1, INSAT-3A) infrared (IR) radiance measurements, are blended with gridded AAODs (500 nm, monthly mean) derived from Ozone Monitoring Instrument (OMI)-retrieved AAODs (at 354 nm and 388 nm). The details of the assimilation methods and the gridded datasets generated are presented in this paper. The merged, gridded AOD and AAOD products thus generated, are validated against the data from independent ground-based observatories, which were not used for the assimilation process, but are representative of different subregions of the complex domain. This validation exercise revealed that the independent ground-based measurements are better confirmed by merged datasets than the respective satellite products. As ensured by assimilation techniques employed, the uncertainties in merged AODs and AAODs are significantly less than those in corresponding satellite products. These merged products also exhibit all important, large-scale spatial and temporal features which are already reported for this region. Nonetheless, the merged AODs and AAODs are significantly different in magnitude, from the respective satellite products. On the background of above mentioned quality enhancements demonstrated by merged products, we have employed them for deriving the columnar SSA and analysed its spatio-temporal characteristics. The columnar SSA thus derived has demonstrated distinct seasonal variation, over various representative subregions of the study domain. The uncertainties in the derived SSA are observed to be substantially less than those in OMI SSA. On the backdrop of these benefits, the merged datasets are employed for the estimation of regional aerosol radiative effects (direct), the results of which would be presented in a companion paper; Part-2 of this two-part paper.

Role of sulphate and carbonaceous aerosols on the radiative effects of aerosols over a remote high-altitude site lachung in the Eastern Himalayas

2021 ◽  
pp. 105799
Author(s):  
B.S. Arun ◽  
Mukunda M. Gogoi ◽  
Arup Borgohain ◽  
Prashant Hegde ◽  
Shyam Sundar Kundu ◽  
...  
Keyword(s):  
High Altitude ◽  
Carbonaceous Aerosols ◽  
Radiative Effects ◽  
Eastern Himalayas

scholarly journals Overview of the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES)

2012 ◽  
Vol 12 (1) ◽  
pp. 1299-1400 ◽  
Author(s):  
R. A. Zaveri ◽  
W. J. Shaw ◽  
D. J. Cziczo ◽  
B. Schmid ◽  
R. A. Ferrare ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Climate Models ◽  
Trace Gases ◽  
Horizontal Distribution ◽  
Primary Objective ◽  
Department Of Energy ◽  
Carbonaceous Aerosol ◽  
Chemical Transformations ◽  
Carbonaceous Aerosols ◽  
Radiative Effects

Abstract. Substantial uncertainties still exist in the scientific understanding of the possible interactions between urban and natural (biogenic) emissions in the production and transformation of atmospheric aerosol and the resulting impact on climate change. The US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program's Carbonaceous Aerosol and Radiative Effects Study (CARES) carried out in June 2010 in Central Valley, California, was a comprehensive effort designed to improve this understanding. The primary objective of the field study was to investigate the evolution of secondary organic and black carbon aerosols and their climate-related properties in the Sacramento urban plume as it was routinely transported into the forested Sierra Nevada foothills area. Urban aerosols and trace gases experienced significant physical and chemical transformations as they mixed with the reactive biogenic hydrocarbons emitted from the forest. Two heavily-instrumented ground sites – one within the Sacramento urban area and another about 40 km to the northeast in the foothills area – were set up to characterize the evolution of meteorological variables, trace gases, aerosol precursors, aerosol size, composition, and climate-related properties in freshly polluted and "aged" urban air. On selected days, the DOE G-1 aircraft was deployed to make similar measurements upwind and across the evolving Sacramento plume in the morning and again in the afternoon. The NASA B-200 aircraft, carrying remote sensing instruments, was also deployed to characterize the vertical and horizontal distribution of aerosols and aerosol optical properties within and around the plume. This overview provides: (a) the scientific background and motivation for the study, (b) the operational and logistical information pertinent to the execution of the study, (c) an overview of key observations and initial results from the aircraft and ground-based sampling platforms, and (d) a roadmap of planned data analyses and focused modeling efforts that will facilitate the integration of new knowledge into improved representations of key aerosol processes in climate models.

scholarly journals Overview of the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES)

2012 ◽  
Vol 12 (16) ◽  
pp. 7647-7687 ◽  
Author(s):  
R. A. Zaveri ◽  
W. J. Shaw ◽  
D. J. Cziczo ◽  
B. Schmid ◽  
R. A. Ferrare ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Climate Models ◽  
Trace Gases ◽  
Horizontal Distribution ◽  
Primary Objective ◽  
Department Of Energy ◽  
Carbonaceous Aerosol ◽  
Chemical Transformations ◽  
Carbonaceous Aerosols ◽  
Radiative Effects

Abstract. Substantial uncertainties still exist in the scientific understanding of the possible interactions between urban and natural (biogenic) emissions in the production and transformation of atmospheric aerosol and the resulting impact on climate change. The US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program's Carbonaceous Aerosol and Radiative Effects Study (CARES) carried out in June 2010 in Central Valley, California, was a comprehensive effort designed to improve this understanding. The primary objective of the field study was to investigate the evolution of secondary organic and black carbon aerosols and their climate-related properties in the Sacramento urban plume as it was routinely transported into the forested Sierra Nevada foothills area. Urban aerosols and trace gases experienced significant physical and chemical transformations as they mixed with the reactive biogenic hydrocarbons emitted from the forest. Two heavily-instrumented ground sites – one within the Sacramento urban area and another about 40 km to the northeast in the foothills area – were set up to characterize the evolution of meteorological variables, trace gases, aerosol precursors, aerosol size, composition, and climate-related properties in freshly polluted and "aged" urban air. On selected days, the DOE G-1 aircraft was deployed to make similar measurements upwind and across the evolving Sacramento plume in the morning and again in the afternoon. The NASA B-200 aircraft, carrying remote sensing instruments, was also deployed to characterize the vertical and horizontal distribution of aerosols and aerosol optical properties within and around the plume. This overview provides: (a) the scientific background and motivation for the study, (b) the operational and logistical information pertinent to the execution of the study, (c) an overview of key observations and initial findings from the aircraft and ground-based sampling platforms, and (d) a roadmap of planned data analyses and focused modeling efforts that will facilitate the integration of new knowledge into improved representations of key aerosol processes and properties in climate models.

Sati

Crisis ◽  
2005 ◽  
Vol 26 (2) ◽  
pp. 73-77 ◽  
Author(s):  
Dinesh Bhugra
Keyword(s):  
Mental Illness ◽  
Psychiatric Disorders ◽  
Indian Subcontinent ◽  
Cultural Factors ◽  
Role Expectations ◽  
Prevention Strategies ◽  
Social Causation ◽  
Gender Role Expectations ◽  
Good Wife ◽  
And Gender

Abstract. Sati as an act of ritual suicide has been reported from the Indian subcontinent, especially among the Hindus, for several centuries. Although legally proscribed, these acts occur even now in modern India. The principle behind such acts has been put forward as the principle of good wife. There is little evidence to suggest that women who commit this act suffer from a formal mental illness. Cultural factors and gender role expectations play a significant role in the act and its consequences. Using recent examples, this paper illustrates the cultural factors, which may be seen as contributing to the act of suicide. Other factors embedded in the act also emphasize that not all suicides have underlying psychiatric disorders and clinicians must take social causation into account while preparing any prevention strategies.

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