Lower tropospheric aerosol loadings over South Africa: The relative contribution of aeolian dust, industrial emissions, and biomass burning

Piketh, S.; Annegarn, H. J.; Tyson, Peter

doi:10.1029/1998jd100014

Cited by 85 publications

(97 citation statements)

References 25 publications

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“…2c). Aerosols associated with these high-level trajectories are likely to have originated in the north-easterly outflow of the Angolan plume (Tyson et al, 1996), where Fe is introduced principally from mineral dust (Piketh et al, 1999), but also possibly from biomass burning (Maenhaut et al, 1996). Soluble aerosol Fe concentrations were significantly lower than the total aerosol Fe values reported in previous studies (4-6.5 pmol m À3 : V .…”

Section: Aerosol and Rain Ironcontrasting

confidence: 53%

Atmospheric iron deposition and sea-surface dissolved iron concentrations in the eastern Atlantic Ocean

Sarthou¹,

Baker²,

Blain³

et al. 2003

Deep Sea Research Part I: Oceanographic Research Papers

182

145

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Atmospheric iron and underway sea-surface dissolved (o0.2 mm) iron (DFe) concentrations were investigated along a north-south transect in the eastern Atlantic Ocean (27 N/16 W-19 S/5 E). Fe concentrations in aerosols and dry deposition fluxes of soluble Fe were at least two orders of magnitude higher in the Saharan dust plume than at the equator or at the extreme south of the transect. A weaker source of atmospheric Fe was also observed in the South Atlantic, possibly originating in southern Africa via the north-easterly outflow of the Angolan plume. Estimations of total atmospheric deposition fluxes (dry plus wet) of soluble Fe suggested that wet deposition dominated in the intertropical convergence zone, due to the very high amount of precipitation and to the fact that a substantial part of Fe was delivered in dissolved form. On the other hand, dry deposition dominated in the other regions of the transect (73-97%), where rainfall rates were much lower. Underway sea-surface DFe concentrations ranged 0.02-1.1 nM. Such low values (0.02 nM) are reported for the first time in the Atlantic Ocean and may be (co)-limiting for primary production. A significant correlation (Spearman's rho=0.862, po0:01) was observed between mean DFe concentrations and total atmospheric deposition fluxes, confirming the importance of atmospheric deposition on the iron cycle in the Atlantic. Residence time of DFe in the surface waters relative to atmospheric inputs were estimated in the northern part of our study area (1778 to 28716 d). These values confirmed the rapid removal of Fe from the surface waters, possibly by colloidal aggregation. r

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Section: Aerosol and Rain Ironcontrasting

confidence: 53%

Atmospheric iron deposition and sea-surface dissolved iron concentrations in the eastern Atlantic Ocean

Sarthou¹,

Baker²,

Blain³

et al. 2003

Deep Sea Research Part I: Oceanographic Research Papers

182

145

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“…Aerosols at Mongu and Skukuza have similar size and distribution properties, although the former is significantly more absorbing (SSA lower by about 0.05), likely due in part to the contribution from nonabsorbing sulfates to the aerosol at Skukuza (Piketh et al, 1999); i.e. the aerosol columns here are less "pure" smoke than elsewhere.…”

Section: Discussion Of Aerosol Propertiesmentioning

confidence: 94%

“…Note that Cuiaba can also sample forest burning from the north, while Skukuza includes a sulfate contribution from industrial sources (Piketh et al, 1999). Mukdahan has a similar SSA to these sites, although with a size distribution and asymmetry parameter closer to Yakutsk/Tomsk 22.…”

Section: Discussion Of Aerosol Propertiesmentioning

confidence: 99%

AERONET-based models of smoke-dominated aerosol near source regions and transported over oceans, and implications for satellite retrievals of aerosol optical depth

et al. 2014

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Abstract. Smoke aerosols from biomass burning are an important component of the global aerosol system. Analysis of Aerosol Robotic Network (AERONET) retrievals of aerosol microphysical/optical parameters at 10 sites reveals variety between biomass burning aerosols in different global source regions, in terms of aerosol particle size and single scatter albedo (SSA). Case studies of smoke observed at coastal/island AERONET sites also mostly lie within the range of variability at the near-source sites. Differences between sites tend to be larger than variability at an individual site, although optical properties for some sites in different regions can be quite similar. Across the sites, typical midvisible SSA ranges from ∼ 0.95-0.97 (sites dominated by boreal forest or peat burning, typically with larger fine-mode particle radius and spread) to ∼ 0.88-0.9 (sites most influenced by grass, shrub, or crop burning, typically smaller finemode particle radius and spread). The tropical forest site Alta Floresta (Brazil) is closer to this second category, although with intermediate SSA ∼ 0.92. The strongest absorption is seen in southern African savannah at Mongu (Zambia), with average midvisible SSA ∼ 0.85. Sites with stronger absorption also tend to have stronger spectral gradients in SSA, becoming more absorbing at longer wavelengths. Microphysical/optical models are presented in detail so as to facilitate their use in radiative transfer calculations, including extension to UV (ultraviolet) wavelengths, and lidar ratios. One intended application is to serve as candidate optical models for use in satellite aerosol optical depth (AOD) retrieval algorithms. The models presently adopted by these algorithms over ocean often have insufficient absorption (i.e. too high SSA) to represent these biomass burning aerosols. The underestimates in satellite-retrieved AOD in smoke outflow regions, which have important consequences for applications of these satellite data sets, are consistent with the level of underestimated absorption.

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“…Persistent atmospheric haze, often referred to as atmospheric brown cloud (ABC) (Ramanathan and Crutzen, 2003), affects broad geographic regions including the Indo-Gangetic plains (IGP) in southern Asia (Ramanathan and Carmichael, 2008), eastern China (Ma et al, 2010), southeast Asia (Engling and Gelencser, 2010), sub-Saharan Africa (Piketh et al, 1999), Mexico (Vasilyev et al, 1995), and Brazil (Kaufman et al, 1998). In southern Asia, the haze covers extensive areas particularly during the period of mid-November to midJune preceding the summer monsoon season.…”

Section: Introductionmentioning

confidence: 99%

Transport of regional pollutants through a remote trans-Himalayan valley in Nepal

Dhungel

Kathayat²,

Mahata

et al. 2018

Atmos. Chem. Phys.

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Abstract. Anthropogenic emissions from the combustion of fossil fuels and biomass in Asia have increased in recent years. High concentrations of reactive trace gases and lightabsorbing and light-scattering particles from these sources form persistent haze layers, also known as atmospheric brown clouds, over the Indo-Gangetic plains (IGP) from December through early June. Models and satellite imagery suggest that strong wind systems within deep Himalayan valleys are major pathways by which pollutants from the IGP are transported to the higher Himalaya. However, observational evidence of the transport of polluted air masses through Himalayan valleys has been lacking to date. To evaluate this pathway, we measured black carbon (BC), ozone (O 3 ), and associated meteorological conditions within the Kali Gandaki Valley (KGV), Nepal, from January 2013 to July 2015. BC and O 3 varied over both diurnal and seasonal cycles. Relative to nighttime, mean BC and O 3 concentrations within the valley were higher during daytime when the up-valley flow (average velocity of 17 m s −1 ) dominated. BC and O 3 concentrations also varied seasonally with minima during the monsoon season (July to September). Concentrations of both species subsequently increased post-monsoon and peaked during March to May. Average concentrations for O 3 during the seasonally representative months of April, August, and November were 41.7, 24.5, and 29.4 ppbv, respectively, while the corresponding BC concentrations were 1.17, 0.24, and 1.01 µg m −3 , respectively. Up-valley fluxes of BC were significantly greater than down-valley fluxes during all seasons. In addition, frequent episodes of BC concentrations 2-3 times higher than average persisted from several days to a week during non-monsoon months. Our observations of increases in BC concentration and fluxes in the valley, particularly during pre-monsoon, provide evidence that trans-Himalayan valleys are important conduits for transport of pollutants from the IGP to the higher Himalaya.

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Lower tropospheric aerosol loadings over South Africa: The relative contribution of aeolian dust, industrial emissions, and biomass burning

Cited by 85 publications

References 25 publications

Atmospheric iron deposition and sea-surface dissolved iron concentrations in the eastern Atlantic Ocean

Atmospheric iron deposition and sea-surface dissolved iron concentrations in the eastern Atlantic Ocean

AERONET-based models of smoke-dominated aerosol near source regions and transported over oceans, and implications for satellite retrievals of aerosol optical depth

Transport of regional pollutants through a remote trans-Himalayan valley in Nepal

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