Aerosol Radiative Forcing and Forcing Efficiency in the UVB for Regions Affected by Saharan and Asian Mineral Dust

García, Omaira; Díaz, A. M.; Expósito, Francisco J.; Dı́az, J. P.; Redondas, Alberto; Sasaki, T.

doi:10.1175/2008jas2816.1

Cited by 12 publications

(7 citation statements)

References 23 publications

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“…Furthermore, there are notable episodes of mineral dust transport from the Gobi-Taklamakan deserts during spring and at the beginning of summer (e.g. Arimoto et al, 2006;García et al, 2009). The south-eastern region of Asia is especially significant because it reflects the growing industrial development of countries such as China.…”

Section: Urban-industrialmentioning

confidence: 99%

“…An AOD average of 0.1 ± 0.1 is obtained in this time period in contrast to 0.02 ± 0.01 recorded during the rest of the year, which approaches the multi-year AOD mean of MLO, 0.04 ± 0.01. This seasonality is governed by the regional meteorological conditions (Azores High and North African Low), which also affect the regions 1 and 2 (Díaz et al, 2006;García et al, 2009). Therefore, the winter can be considered as representative of free troposphere conditions (AOD season mean of 0.03 ± 0.02) to estimate the aerosol radiative forcing in this region.…”

Section: Free Tropospherementioning

confidence: 99%

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Shortwave radiative forcing and efficiency of key aerosol types using AERONET data

et al. 2012

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Abstract. The shortwave radiative forcing ( F ) and the radiative forcing efficiency ( F eff ) of natural and anthropogenic aerosols have been analyzed using estimates of radiation both at the Top (TOA) and at the Bottom Of Atmosphere (BOA) modeled based on AERONET aerosol retrievals. Six main types of atmospheric aerosols have been compared (desert mineral dust, biomass burning, urbanindustrial, continental background, oceanic and free troposphere) in similar observational conditions (i.e., for solar zenith angles between 55 • and 65 • ) in order to compare the nearly same solar geometry. The instantaneous F averages obtained vary from −122 ± 37 Wm −2 (aerosol optical depth, AOD, at 0.55 µm, 0.85 ± 0.45) at the BOA for the mixture of desert mineral dust and biomass burning aerosols in West Africa and −42 ± 22 Wm −2 (AOD = 0.9 ± 0.5) at the TOA for the pure mineral dust also in this region up to −6 ± 3 Wm −2 and −4 ± 2 Wm −2 (AOD = 0.03 ± 0.02) at the BOA and the TOA, respectively, for free troposphere conditions. This last result may be taken as reference on a global scale. Furthermore, we observe that the more absorbing aerosols are overall more efficient at the BOA in contrast to at the TOA, where they backscatter less solar energy into the space. The analysis of the radiative balance at the TOA shows that, together with the amount of aerosols and their absorptive capacity, it is essential to consider the surface albedo of the region on which they are. Thus, we document that in regions with high surface reflectivity (deserts and snow conditions) atmospheric aerosols lead to a warming of the Earthatmosphere system.

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Section: Urban-industrialmentioning

confidence: 99%

Section: Free Tropospherementioning

confidence: 99%

Shortwave radiative forcing and efficiency of key aerosol types using AERONET data

et al. 2012

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“…Lower single scattering albedo and effective radius are also recorded. Consequently the aerosol mixture in winter has a greater absorption capacity than the pure mineral, since biomass burning particles (elemental carbon) enhance the absorption of solar radiation (higher imaginary part of refractive index) [ Arimoto et al , 2006; Lyamani et al , 2006; Derimian et al , 2008; García et al , 2008b]. For example, during the winter the interannual average of single scattering albedo derived by AERONET, ω (0.44/0.67/0.87/1.02 μ m) = 0.84/0.88/0.90/0.91 ± (0.04–0.05) and ω = 0.83/0.86/0.87/0.88 ± (0.05–0.07) for Ilorin and Djougou, respectively, are lower than those observed at these stations during the rest of the year of ω = 0.90/0.94/0.95/0.96 ± 0.04 in Ilorin and ω = 0.89/0.93/0.95/0.96 ± 0.04 at Djougou, revealing most absorbing aerosols during winter (Figure 2c).…”

Section: Site Descriptionsmentioning

confidence: 99%

Radiative forcing under mixed aerosol conditions

et al. 2011

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[1] The mixture of mineral dust with biomass burning or urban-industrial aerosols presents significant differences in optical properties when compared to those of the individual constituents, leading to different impacts on solar radiation levels. This effect is assessed by estimating the direct radiative forcing (DF) of these aerosols from solar flux models using the radiative parameters derived from the Aerosol Robotic Network (AERONET). These data reveal that, in oceanic and vegetative covers (surface albedo (SA) < 0.30), the aerosol effect at the top of atmosphere (TOA)

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“…Studies on the evaluation of radiative effects of desert dust on UVB irradiance levels by means of radiative forcing and forcing efficiency over Sahara-Sahel and Gibo deserts show that the net effect of radiative forcing estimates for the two regions in the UVB spectral range are comparable (Garcіa et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Investigation of Radiative Characteristics of the Kenyan Atmosphere due to Aerosols Using Sun Spectrophotometry Measurements and the COART Model

Makokha

Angeyo

2013

Aerosol Air Qual. Res.

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Variations in the radiative characteristics of aerosols can be used to quantify their effects on climate. This study evaluated the temporal-spatial variability of aerosol radiative characteristics at λ = 440 nm, λ = 675 nm, λ = 870 nm and λ = 1020 nm over the Nairobi-1°S, 36°E, Mbita-0°S, 34°E and Malindi-2°S, 40°E sites of Kenya. Aerosol optical properties from AERONET were used as inputs in the Coupled Ocean Atmosphere Radiative Transfer (COART) code to model aerosol radiative effects. The results over Nairobi showed an increase in reflectance of 2.6%, 6.7%, 7.2% and 2.4% for 2006-2007 at the specified wavelengths, respectively. Drops of 2.7%, 12.2%, 50.6% and 25.6% were noted in the same wavelengths for the 2007-2008 period. The reflectance over Mbita (0.2284) was higher than that over Nairobi (0.1396) at λ = 675 nm for 2007, due to biomass burning at site. Maritime conditions and aerosols coupled with long range transport of monsoon winds explain the higher reflectance observed over Malindi when compared to Nairobi, except for λ = 440 nm in 2008. This is as a result of aerosols from vehicular and industrial emissions that dominate the λ = 440 nm over Nairobi. The variability of downward and upward spectral irradiance measured at the surface and 12 km levels depended on the wavelength of measurement, but was temporally invariant. Upward irradiance decreased with increasing Solar Zenith Angles (SZAs) due to strong Fresnel reflection at large angles. The equality in the upwelling irradiances at the two atmospheric levels at all sites for λ = 870 nm and λ = 1020 nm was due to the near IR absorption by aerosols. The radiant flux lost in the spectral range 440-1020 nm remained relatively constant over the study sites, and thus the influence of aerosols on radiative characteristics was independent of both site and period of study.

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Aerosol Radiative Forcing and Forcing Efficiency in the UVB for Regions Affected by Saharan and Asian Mineral Dust

Cited by 12 publications

References 23 publications

Shortwave radiative forcing and efficiency of key aerosol types using AERONET data

Shortwave radiative forcing and efficiency of key aerosol types using AERONET data

Radiative forcing under mixed aerosol conditions

Investigation of Radiative Characteristics of the Kenyan Atmosphere due to Aerosols Using Sun Spectrophotometry Measurements and the COART Model

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