Vertical profiles of black carbon aerosols over the urban locations in South India

Safai, P.D.; Raju, M.P.; Maheshkumar, R. S.; Kulkarni, J. R.; Rao, P. S. P.; Devara, P. C. S.

doi:10.1016/j.scitotenv.2012.05.058

Cited by 41 publications

(24 citation statements)

References 33 publications

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“…Sinha et al (2013) found that aerosols within atmospheric boundary layer (ABL) over a tropical urban station Hyderabad, India dominated the column aerosol loading with ABL-AOD, contributing not less than 50 % throughout the year. Over urban locations in South India, BC mass loadings decreased approximately monotonically from the surface to an altitude of 7 km (Safai et al, 2012). Atmospheric species concentrated in the ABL are "occasionally transported to the free troposphere in 'uplifted plumes' via systematic vertical motions of air" (Moteki et al, 2012).…”

Section: Xu Et Al: Similarities and Differences Of Aerosol Opticamentioning

confidence: 99%

Similarities and differences of aerosol optical properties between southern and northern sides of the Himalayas

Panday

et al. 2014

Atmos. Chem. Phys.

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Abstract. The Himalaya mountains along the southern edge of the Tibetan Plateau act as a natural barrier for the transport of atmospheric aerosols from the polluted regions of South Asia to the main body of the Tibetan Plateau. In this study, we investigate the seasonal and diurnal variations of aerosol optical properties measured at two Aerosol Robotic Network (AERONET) sites on the southern side of the Himalaya (Pokhara, 812 m above sea level (a.s.l.) and EVK2-CNR, 5079 m a.s.l. in Nepal) and one on the northern side (Qomolangma (Mt. Everest) station for Atmospheric and Environmental Observation and Research, Chinese Academy of Sciences (QOMS_CAS) in Tibet, 4076 m a.s.l. in China). While observations at QOMS_CAS and EVK2-CNR can generally be representative of a remote background atmosphere, Pokhara is a lower-elevation suburban site with much higher aerosol load due to both the influence of local anthropogenic activities and to its proximity to the Indo-Gangetic Plains. The annual mean aerosol optical depth (AOD) during the investigated period was 0.05 at QOMS_CAS, 0.04 at EVK2-CNR and 0.51 at Pokhara, respectively. Seasonal variations of aerosols are profoundly affected by large-scale atmospheric circulation. Vegetation fires, peaking during April in the Himalayan region and northern India, contribute to a growing fine mode AOD at the three stations. Dust transported to these sites, wind erosion and hydrated/cloudprocessed aerosols lead to an increase in coarse mode AOD during the monsoon season at QOMS_CAS and EVK2-CNR. Meanwhile, coarse mode AOD at EVK2-CNR is higher than at QOMS_CAS in August and September, indicating that the transport of coarse mode aerosols from the southern to the northern side may be effectively reduced. The effect of precipitation scavenging is clearly seen at Pokhara, which sees significantly reduced aerosol loads during the monsoon season. Unlike the seasonal variations, diurnal variations are mainly influenced by meso-scale systems and local topography. The diurnal pattern in precipitation appears to contribute to diurnal changes in AOD through the effect of precipitation scavenging. AOD exhibits diurnal patterns related to emissions in Pokhara, while it does not at the other two high-altitude sites. At EVK2-CNR, the daytime airflow carries aerosols up from lower-altitude polluted regions, leading to increasing AOD, while the other two stations are less influenced by valley winds. Surface heating influences the local convection, which further controls the vertical aerosol exchange and the diffusion rate of pollution to the surrounding areas. Fine and coarse mode particles Published by Copernicus Publications on behalf of the European Geosciences Union. C. Xu et al.: Similarities and differences of aerosol optical propertiesare mixed together on the southern side of the Himalaya in spring, which may lead to the greater inter-annual difference in diurnal cycles of Ångström exponent (AE) at EVK2-CNR than that at QOMS_CAS.

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Section: Xu Et Al: Similarities and Differences Of Aerosol Opticamentioning

confidence: 99%

Similarities and differences of aerosol optical properties between southern and northern sides of the Himalayas

Panday

et al. 2014

Atmos. Chem. Phys.

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“…The Aethalometer was operated at a flow rate of 6.5 l min −1 and the observations were taken at 1 min intervals. The sampling inlet of the Aethalometer was connected to the common isokinetic Brechtel double diffuser inlet by using a 1.5 m long polyurethane tube (Safai et al , ). The particle loss was minimized using the polyurethane conductive tubing.…”

Section: Methodsmentioning

confidence: 99%

Indirect forcing of black carbon on clouds over northeast India

Panicker

Pandithurai

Safai

et al. 2016

Quart J Royal Meteoro Soc

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Black carbon (BC) induced indirect radiative forcing and cloud albedo effect has been studied for the first time over northeast India. Measurements of BC and cloud microphysical parameters were carried out during Phase‐I of the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) over northeast India (Guwahati) in 2009. Liquid water path (LWP) in the cloud layers coherent with BC on different experimental days was found to be 206–327 g m−2 over the region. Black carbon aerosol indirect effect (BCIE) for fixed LWP is found to be 0.32–0.48 on different days of observations. The indirect forcing corresponding to this BCIE has been estimated using a radiative transfer model for fixed LWP by altering the derived BC‐AOD (aerosol optical depth from measured BC profiles) and cloud effective radius (Re) combinations. The estimated average BC‐induced indirect forcing (BCIF) was −24 to −37.1 W m−2 at the surface and +2.5 to +14.8 W m−2 at the top of the atmosphere (TOA). The average albedo due to BCIF at TOA was 0.49–0.61. BCIF is found to reduce the cloud reflection by 1.5–2% over the region. The sensitivities of cloud parameters to BCIF and the albedo effect are illustrated.

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“…The sampling inlet of the Aethalometer was connected by using a 1.5 m long polyurethane tube (a non-conductive tubing to minimize the particle losses) to the common isokinetic Brechtel double diffuser inlet that was mounted on the pressurized part of the aircraft facing the airflow through a manifold within the fuselage. Standard procedures were adapted to calibrate the aircraft instruments during the campaign42. The measurement uncertainty in spite of the corrections used to the raw Aethalometer BC data was ± 15% or about 20 ng/m 3 in terms of BC mass concentration.…”

Section: Methodsmentioning

confidence: 99%

Double blanket effect caused by two layers of black carbon aerosols escalates warming in the Brahmaputra River Valley

Rahul

Bhawar

Ayantika

et al. 2014

Sci Rep

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First ever 3-day aircraft observations of vertical profiles of Black Carbon (BC) were obtained during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) conducted on 30th August, 4th and 6th September 2009 over Guwahati (26°11′N, 91°44′E), the largest metropolitan city in the Brahmaputra River Valley (BRV) region. The results revealed that apart from the surface/near surface loading of BC due to anthropogenic processes causing a heating of 2 K/day, the large-scale Walker and Hadley atmospheric circulations associated with the Indian summer monsoon help in the formation of a second layer of black carbon in the upper atmosphere, which generates an upper atmospheric heating of ~2 K/day. Lofting of BC aerosols by these large-scale circulating atmospheric cells to the upper atmosphere (4–6 Km) could also be the reason for extreme climate change scenarios that are being witnessed in the BRV region.

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Vertical profiles of black carbon aerosols over the urban locations in South India

Cited by 41 publications

References 33 publications

Similarities and differences of aerosol optical properties between southern and northern sides of the Himalayas

Similarities and differences of aerosol optical properties between southern and northern sides of the Himalayas

Indirect forcing of black carbon on clouds over northeast India

Double blanket effect caused by two layers of black carbon aerosols escalates warming in the Brahmaputra River Valley

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