Vertical structure of aerosols and water vapor over West Africa during the African monsoon dry season

Kim, S.-W.; Chazette, Patrick; Dulac, François; Sanak, J.; Johnson, Ben; Yoon, Soon‐Chang

doi:10.5194/acp-9-8017-2009

Cited by 26 publications

(21 citation statements)

References 48 publications

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“…The difference between sites is larger than this: α abs for Bonanza Creek, Tomsk 22, and Yakutsk (but not Moscow), likely dominated by smouldering combustion, is larger than for the other sites by typically ∼ 0.4. These values are similar to those determined by other techniques over similar wavelength ranges (data analysed and collated by Kirchstetter et al, 2004), i.e. generally ∼ 1-2, with lower values associated with increased soot, and higher with increased organic carbon, although there is some sensitivity to the precise wavelength interval used in such calculations.…”

Section: A M Sayer Et Al: Smoke Aerosol Propertiessupporting

confidence: 67%

“…Note that α abs for these sites is generally more positive by 0.2-0.5 than calculations performed by Russell et al (2010) using the AERONET version 1 smoke models from Dubovik et al (2002); however, the differences between sites remain similar. Computations over other wavelength ranges (omitted for brevity) are also in the range of values for smoke aerosols determined in other studies (Kirchstetter et al, 2004;Bergstrom et al, 2007). The relationships between all these properties and wv were also explored, but in most cases omitted for brevity due to a lack of observed covariability.…”

Section: A M Sayer Et Al: Smoke Aerosol Propertiesmentioning

confidence: 99%

“…Geographical/sampling information for biomass burning AERONET land sites, along with some references for burning in these regions. Cottle et al (2014) microphysical model based on column-average aerosol properties, when applied to real satellite data, could potentially be misleading or inaccurate (Kim et al, 2009). A similar rationale applies to sites in the Indo-Gangetic Plain and Himalayas (e.g.…”

Section: Site Selectionmentioning

confidence: 99%

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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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Section: A M Sayer Et Al: Smoke Aerosol Propertiessupporting

confidence: 67%

Section: A M Sayer Et Al: Smoke Aerosol Propertiesmentioning

confidence: 99%

Section: Site Selectionmentioning

confidence: 99%

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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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“…In summertime easterly transport occurs above 1.5 km in the Saharan Air Layer (SAL) through the African Easterly Jet (AEJ) that blows over 1.5 km and is strongest at around 4.5 km at the latitude of Niamey (Kalapureddy et al, 2010). This contrasts with the surface transport pattern occurring during wintertime (Kalu, 1979;Chiapello et al, 1995;Osborne et al, 2008;Heese and Wiegner, 2008;Kim et al, 2009;Léon et al, 2009).…”

Section: Aerosol Particle Absorption Coefficientsmentioning

confidence: 42%

Airborne observations of mineral dust over western Africa in the summer Monsoon season: spatial and vertical variability of physico-chemical and optical properties

Formenti

Rajot²,

Desboeufs³

et al. 2011

Atmos. Chem. Phys.

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Abstract. We performed airborne measurements of aerosol particle concentration, composition, size distribution and optical properties over Western Africa in the corridor 2-17 • N and 3-5 • E. Data were collected on board the French ATR-42 research aircraft in June-July 2006 as part of the African Monsoon Multidisciplinary Analysis (AMMA) intensive field phases in June-July 2006 using the AVIRAD airborne aerosol sampling system.The aerosol vertical distribution was documented on an almost daily basis. In particular, the vertical distribution of mineral dust emitted locally by Mesoscale Convective Systems (MSC) was distinguished from that of mineral dust that was transported from the Saharan by the African Easterly Jet (AEJ). Mineral dust emitted in the Sahel by convectiondriven erosion was mostly confined in the boundary layer. One episode of injection of Sahelian mineral dust in the AEJ was observed. The elemental composition was found to be an element of difference between episodes, whereas the volume size distribution was more uniform.For non-mixed dust, the single scattering albedo ranged between 0.88-0.93 at 370 nm and between 0.91-0.99 at 950 nm, lower values being observed for Sahelian dust. In correspondence, the imaginary part of the complex refractive index varied between 0.002-0.004 at 370 nm and between 0.001-0.002 at 950 nm.

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“…For example, Haywood et al (2008) determined the vertical distribution of West African aerosols during the fire season, showing that a dust layer exists at the surface while an elevated smoke layer persists above. New chemically resolved aerosol observations are described in Capes et al (2009), , Kim et al (2009), Chou et al (2008), Johnson et al (2008), Osborne et al (2008), Rajot et al (2008). Heterogeneous processes have been studied by Crumeyrolle et al (2009) and Matsuki et al (2010).…”

Section: Introductionmentioning

confidence: 99%

Updated African biomass burning emission inventories in the framework of the AMMA-IDAF program, with an evaluation of combustion aerosols

et al. 2010

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Abstract. African biomass burning emission inventories for gaseous and particulate species have been constructed at a resolution of 1 km by 1km with daily coverage for the 2000-2007 period. These inventories are higher than the GFED2 inventories, which are currently widely in use. Evaluation specifically focusing on combustion aerosol has been carried out with the ORISAM-TM4 global chemistry transport model which includes a detailed aerosol module. This paper compares modeled results with measurements of surface BC concentrations and scattering coefficients from the AMMA Enhanced Observations period, aerosol optical depths and single scattering albedo from AERONET sunphotometers, LIDAR vertical distributions of extinction coefficients as well as satellite data. Aerosol seasonal and interannual evolutions over the 2004-2007 period observed at regional scale and more specifically at the Djougou (Benin) and Banizoumbou (Niger) AMMA/IDAF sites are well reproduced by our global model, indicating that our biomass burning emission inventory appears reasonable.

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Vertical structure of aerosols and water vapor over West Africa during the African monsoon dry season

Abstract: Abstract. We present observations of tropospheric aerosol and water vapor transport over West Africa and the associated meteorological conditions during the AMMA SOP-0 dry season experiment, which was conducted in West

Cited by 26 publications

References 48 publications

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

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

Airborne observations of mineral dust over western Africa in the summer Monsoon season: spatial and vertical variability of physico-chemical and optical properties

Updated African biomass burning emission inventories in the framework of the AMMA-IDAF program, with an evaluation of combustion aerosols

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