Physical properties and concentration of aerosol particles over the Amazon tropical forest during background and biomass burning conditions

Guyon, Pascal; Graham, Bimbil; Beck, Jonathan; Boucher, Oliviér; Gerasopoulos, E.; Mayol-Bracero, O. L.; Roberts, Grégory; Artaxo, Paulo; Andreae, Meinrat O.

doi:10.5194/acp-3-951-2003

Cited by 72 publications

(64 citation statements)

References 57 publications

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“…We found low CN concentrations (300-500 cm −3 ) basinwide, confirming other local CN measurements in clean parts of Amazonia during previous campaigns Guyon et al, 2003;Andreae et al, 2004;Rissler et al, 2004;Andreae, 2009). The CO mixing ratios in the PBL were elevated by only ∼10 ppb above the values in air entering the Basin from the Atlantic, and no CO enhancement was evident in the FT.…”

Section: Discussionsupporting

confidence: 71%

Carbon monoxide and related trace gases and aerosols over the Amazon Basin during the wet and dry seasons

Artaxo²,

et al. 2012

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Abstract. We present the results of airborne measurements of carbon monoxide (CO) and aerosol particle number concentration (CN) made during the Balanço Atmosférico Regional de Carbono na Amazônia (BARCA) program. The primary goal of BARCA is to address the question of basinscale sources and sinks of CO 2 and other atmospheric carbon species, a central issue of the Large-scale BiosphereAtmosphere (LBA) program. The experiment consisted of two aircraft campaigns during November-December 2008 (BARCA-A) and May-June 2009 (BARCA-B), which covered the altitude range from the surface up to about 4500 m, and spanned most of the Amazon Basin.Based on meteorological analysis and measurements of the tracer, SF 6 , we found that airmasses over the Amazon Basin during the late dry season (BARCA-A, November 2008) originated predominantly from the Southern Hemisphere, while during the late wet season (BARCA-B, May 2009) low-level airmasses were dominated by northernhemispheric inflow and mid-tropospheric airmasses were of mixed origin. In BARCA-A we found strong influence of biomass burning emissions on the composition of the atmosphere over much of the Amazon Basin, with CO enhancements up to 300 ppb and CN concentrations approaching 10 000 cm −3 ; the highest values were in the southern part of the Basin at altitudes of 1-3 km. The CN/ CO ratios were diagnostic for biomass burning emissions, and were lower in aged than in fresh smoke. Fresh emissions indicated CO/CO 2 and CN/CO emission ratios in good agreement with previous work, but our results also highlight the need to consider the residual smoldering combustion that takes place after the active flaming phase of deforestation fires.During the late wet season, in contrast, there was little evidence for a significant presence of biomass smoke. Low CN concentrations (300-500 cm −3 ) prevailed basinwide, and CO mixing ratios were enhanced by only ∼10 ppb above the mixing line between Northern and Southern Hemisphere air. There was no detectable trend in CO with distance from the coast, but there was a small enhancement of CO in the boundary layer suggesting diffuse biogenic sources from photochemical degradation of biogenic volatile organic compounds or direct biological emission.Simulations of CO distributions during BARCA-A using a range of models yielded general agreement in spatial distribution and confirm the important contribution from biomass burning emissions, but the models evidence some systematic quantitative differences compared to observed CO concentrations. These mismatches appear to be related to problems with the accuracy of the global background fields, the role Published by Copernicus Publications on behalf of the European Geosciences Union. M. O. Andreae et al.: Carbon monoxide and related trace gases and aerosolsof vertical transport and biomass smoke injection height, the choice of model resolution, and reliability and temporal resolution of the emissions data base.

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Section: Discussionsupporting

confidence: 71%

Carbon monoxide and related trace gases and aerosols over the Amazon Basin during the wet and dry seasons

Artaxo²,

et al. 2012

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“…2) and at our ground site at the beginning of the rainy season. These values are slightly higher than the lowest campaign-average values observed previously over the Amazon [380 to 390 cm Ϫ3 (8,13)] and about twice as high as typical values in the marine boundary layer (MBL) over the Atlantic off Brazil. The slight enhancement observed during our campaign as compared to previous observations over Amazonia may be because of reduced washout during the dry season (previous data were from the wet season) or from minor smoke inputs.…”

Section: Resultsmentioning

confidence: 43%

“…Reduction of evaporation from the Mediterranean Sea by pollution from northern and eastern Europe was modeled to reduce cloud formation and precipitation over the Mediterranean region (12), in general agreement with measurements (13). However, warming of the atmosphere by similar widespread pollution aerosol over southeastern China was modeled to cause uplift of the polluted air mass over an area of 10 million km 2 , which then was replaced by cooler moist air from the nearby Pacific Ocean, causing an increase in precipitation and flooding that fits observations from this region in recent years (14).…”

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confidence: 54%

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Smoking Rain Clouds over the Amazon

Andreae

Rosenfeld

Artaxo

et al. 2004

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Heavy smoke from forest fires in the Amazon was observed to reduce cloud droplet size and so delay the onset of precipitation from 1.5 kilometers above cloud base in pristine clouds to more than 5 kilometers in polluted clouds and more than 7 kilometers in pyro-clouds. Suppression of low-level rainout and aerosol washout allows transport of water and smoke to upper levels, where the clouds appear “smoking” as they detrain much of the pollution. Elevating the onset of precipitation allows invigoration of the updrafts, causing intense thunderstorms, large hail, and greater likelihood for overshooting cloud tops into the stratosphere. There, detrained pollutants and water vapor would have profound radiative impacts on the climate system. The invigorated storms release the latent heat higher in the atmosphere. This should substantially affect the regional and global circulation systems. Together, these processes affect the water cycle, the pollution burden of the atmosphere, and the dynamics of atmospheric circulation.

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“…Over the continental Southern Hemisphere, excluding equatorial Amazonia (Guyon et al, 2003), long-term studies of atmospheric aerosols are limited compared to the vast area it covers (Jayaratne and Verma, 2001;Swap et al, 2003;Ross et al, 2003;Laakso et al, 2006;Suni et al, 2008;Rissler et al, 2006;Vakkari et al, 2011;Queface et al, 2011;Hirsikko et al, 2012;Venter al., 2012). On the African continent south of the equatorial region, number concentrations and…”

Section: Introductionmentioning

confidence: 99%

South African EUCAARI measurements: seasonal variation of trace gases and aerosol optical properties

et al. 2012

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Abstract. In this paper we introduce new in situ observations of atmospheric aerosols, especially chemical composition, physical and optical properties, on the eastern brink of the heavily polluted Highveld area in South Africa. During the observation period between 11 February 2009 and 31 January 2011, the mean particle number concentration (size range 10-840 nm) was 6310 cm −3 and the estimated volume of sub-10 µm particles 9.3 µm 3 m −3 . The aerosol absorption and scattering coefficients at 637 nm were 8.3 Mm −1 and 49.5 Mm −1 , respectively. The mean single-scattering albedo at 637 nm was 0.84 and theÅngström exponent of scattering was 1.5 over the wavelength range 450-635 nm. The mean O 3 , SO 2 , NO x and H 2 S-concentrations were 37.1, 11.5, 15.1 and 3.2 ppb, respectively. The observed range of concentrations was large and attributed to the seasonal variation of sources and regional meteorological effects, especially the anticyclonic re-circulation and strong winter-time inversions. In a global context, the levels of gases and particulates were typical for continental sites with strong anthropogenic influence, but clearly lower than the most polluted areas of southeastern Asia. Of all pollutants observed at the site, ozone is the most likely to have adverse environmental effects, as the concentrations were high also during the growing season. The measurements presented here will help to close existing gaps in the ground-based global atmosphere observation system, since very little long-term data of this nature is available for southern Africa.

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Physical properties and concentration of aerosol particles over the Amazon tropical forest during background and biomass burning conditions

Cited by 72 publications

References 57 publications

Carbon monoxide and related trace gases and aerosols over the Amazon Basin during the wet and dry seasons

Carbon monoxide and related trace gases and aerosols over the Amazon Basin during the wet and dry seasons

Smoking Rain Clouds over the Amazon

South African EUCAARI measurements: seasonal variation of trace gases and aerosol optical properties

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