Analysis of Aerosol Optical Properties due to a Haze Episode in the Himalayan Foothills: Implications for Climate Forcing

Alam, Khan; Khan, Razaullah; Sorooshian, Armin; Blaschke, Thomas; Bibi, Samina; Bibi, Humera

doi:10.4209/aaqr.2017.06.0222

Cited by 18 publications

(10 citation statements)

References 82 publications

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“…The seasonal reduction in median ASY values from 440 to 1020 nm in this study was only 0.02 for DJF, MAM, and SON, whereas it was 0.05 for JJA mostly due to an abnormally high value of 0.74 at 440 nm in August. These reductions are not as pronounced as the previously mentioned studies (Alam et al., 2014, 2018; Bibi et al., 2016; Yu et al., 2016), which presumably is due to the higher relative abundance of sea salt at Bermuda compared to sites closer to sources of fine anthropogenic aerosols. At fixed AOD, fine particles have been shown to exhibit lower ASY values as compared to coarse particles (Bi et al., 2014).…”

Section: Resultscontrasting

confidence: 47%

“…Values for Bermuda are fairly similar to those reported for other regions at various wavelengths (Table 2), including 0.7 (550 nm) for the U.S. East Coast (Hartley & Hobbs, 2001). Past studies suggest that a decreasing trend in ASY with increasing wavelength owes to aerosols being predominantly smaller in size (Alam et al., 2014, 2018; Bibi et al., 2016; Yu et al., 2016). The seasonal reduction in median ASY values from 440 to 1020 nm in this study was only 0.02 for DJF, MAM, and SON, whereas it was 0.05 for JJA mostly due to an abnormally high value of 0.74 at 440 nm in August.…”

Section: Resultsmentioning

confidence: 99%

“…10.1029/2020JD034038 10 of 24 ously mentioned studies (Alam et al, 2014(Alam et al, , 2018Bibi et al, 2016;Yu et al, 2016), which presumably is due to the higher relative abundance of sea salt at Bermuda compared to sites closer to sources of fine anthropogenic aerosols. At fixed AOD, fine particles have been shown to exhibit lower ASY values as compared to coarse particles (Bi et al, 2014).…”

Section: Asymmetry Factormentioning

confidence: 99%

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An Aerosol Climatology and Implications for Clouds at a Remote Marine Site: Case Study Over Bermuda

et al. 2021

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Aerosol characteristics and aerosol–cloud interactions remain uncertain in remote marine regions. We use over a decade of data (2000–2012) from the NASA AErosol RObotic NETwork, aerosol and wet deposition samples, satellite remote sensors, and models to examine aerosol and cloud droplet number characteristics at a representative open ocean site (Bermuda) over the Western North Atlantic Ocean (WNAO). Annual mean values were as follows: aerosol optical depth (AOD) = 0.12, Ångström Exponent (440/870 nm) = 0.95, fine mode fraction = 0.51, asymmetry factor = 0.72 (440 nm) and 0.68 (1020 nm), and Aqua‐MODIS cloud droplet number concentrations = 51.3 cm−3. The winter season (December–February) was characterized by high sea salt optical thickness and the highest aerosol extinction in the lowest 2 km. Extensive precipitation over the WNAO in winter helps contribute to the low FMFs in winter (∼0.40–0.50) even though air trajectories often originate over North America. Spring and summer had more pronounced influence from sulfate, dust, organic carbon, and black carbon. Volume size distributions were bimodal with a dominant coarse mode (effective radii: 1.85–2.09 µm) and less pronounced fine mode (0.14–0.16 µm), with variability in the coarse mode likely due to different characteristic sizes for transported dust (smaller) versus regional sea salt (larger). Extreme pollution events highlight the sensitivity of this site to long‐range transport of urban emissions, dust, and smoke. Differing annual cycles are identified between AOD and cloud droplet number concentrations, motivating a deeper look into aerosol–cloud interactions at this site.

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Section: Resultscontrasting

confidence: 47%

Section: Resultsmentioning

confidence: 99%

Section: Asymmetry Factormentioning

confidence: 99%

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An Aerosol Climatology and Implications for Clouds at a Remote Marine Site: Case Study Over Bermuda

et al. 2021

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“…Finally, all of these parameters have been supported by the additional data, such as optical thickness of clouds, satellite AOD, cloud fraction from MODIS (moderate resolution imaging spectroradiometer), which widely used for analyzing the aerosol distributions from regional to global scales [70]. The MODIS sensors take~5 min to collect a~2300 km scene during the overpass [8,71] that, occurs two timed a day (~10.30 and~13.30) above Svalbard region.…”

Section: Columnar Integrated Datamentioning

confidence: 99%

Study of Chemical and Optical Properties of Biomass Burning Aerosols during Long-Range Transport Events toward the Arctic in Summer 2017

et al. 2020

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Biomass burning related aerosol episodes are becoming a serious threat to the radiative balance of the Arctic region. Since early July 2017 intense wildfires were recorded between August and September in Canada and Greenland, covering an area up to 4674 km2 in size. This paper describes the impact of these biomass burning (BB) events measured over Svalbard, using an ensemble of ground-based, columnar, and vertically-resolved techniques. BB influenced the aerosol chemistry via nitrates and oxalates, which exhibited an increase in their concentrations in all of size fractions, indicating the BB origin of particles. The absorption coefficient data (530 nm) at ground reached values up to 0.6 Mm–1, highlighting the impact of these BB events when compared to average Arctic background values, which do not exceed 0.05 Mm–1. The absorption behavior is fundamental as implies a subsequent atmospheric heating. At the same time, the AERONET Aerosol Optical Depth (AOD) data showed high values at stations located close to or in Canada (AOD over 2.0). Similarly, increased values of AODs were then observed in Svalbard, e.g., in Hornsund (daily average AODs exceeded 0.14 and reached hourly values up to 0.5). Elevated values of AODs were then registered in Sodankylä and Andenes (daily average AODs exceeding 0.150) a few days after the Svalbard observation of the event highlighting the BB columnar magnitude, which is crucial for the radiative impact. All the reported data suggest to rank the summer 2017 plume of aerosols as one of the biggest atmosphere related environmental problems over Svalbard region in last 10 years.

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“…Comparatively moderate concentrations were noted in autumn 2015 (622 ± 277 μg m -3 ), spring 2016 (612±338 μg m -3 ) and summer 2016 (757 ± 301 μg m -3 ), while lowest concentrations were observed in the monsoon 2016 (283 ± 76 μg m -3 ). In autumn season, higher particulate concentrations were appeared due to massive burning of crop remnants so that fields can be cleared for next cultivation [27,28]. Due to heavy smog episode in autumn 2016, about 1.7 times higher PM10 concentrations were recorded as compared to autumn 2015.…”

Section: Results and Discussion Pm10 Concentrationmentioning

confidence: 99%

Elemental Composition of Particulate Matter in South-Asian Megacity (Faisalabad-Pakistan): Seasonal Behaviors, Source Apportionment and Health Risk Assessment

Alvi¹,

Mahmud²,

Kistler³

et al. 2020

Rev. Chim.

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The composition of atmospheric aerosols can help to identify pollution sources, particulate transportation and possible impacts on human health. In this study, seasonal variations and sources of elemental contents in PM10 from Faisalabad area were investigated. In total 117 samples were collected on 24 hours basis from September 2015 to December 2016. The selected trace elements, viz., Al, Ba, Ca, Fe, K, Mg, Mn, Na, P, Pb, S and Zn were measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The average PM10 concentration was found to be 744 � 392 μg m-3, exceeding the limits proposed by Pak-EPA (150 μg m-3), US-EPA (150 μg m-3) and WHO (50 μg m-3). On average concentration basis, the elements were in the order of Ca ] Al ] S ] Fe ] K ] Mg ] Zn ] Na ] Pb ] P ] Mn ] Ba. The elements apparently emitted from natural sources were dominant in spring and summer seasons, while those emitted from anthropogenic inputs were more prominent in winter and autumn seasons. A correlation analysis revealed that pairs of elements originated from common sources were suspended in the ambient air. The enrichment factors (EFs), principal component analysis (PCA) and cluster analysis (CA) indicated wind-blown dust, biomass burning, fossil fuel combustion and vehicular exhaust/non-exhaust emissions as major sources. A health risk caused by non-carcinogenic trace elements such as Pb, Zn and Mn was also assessed according to the method specified by US-EPA.

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Analysis of Aerosol Optical Properties due to a Haze Episode in the Himalayan Foothills: Implications for Climate Forcing

Cited by 18 publications

References 82 publications

An Aerosol Climatology and Implications for Clouds at a Remote Marine Site: Case Study Over Bermuda

An Aerosol Climatology and Implications for Clouds at a Remote Marine Site: Case Study Over Bermuda

Study of Chemical and Optical Properties of Biomass Burning Aerosols during Long-Range Transport Events toward the Arctic in Summer 2017

Elemental Composition of Particulate Matter in South-Asian Megacity (Faisalabad-Pakistan): Seasonal Behaviors, Source Apportionment and Health Risk Assessment

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