Measurements of irradiance attenuation and estimation of aerosol single scattering albedo for biomass burning aerosols in Amazonia

Eck, T. F.; Holben, B. N.; Slutsker, I.; Setzer, Alberto

doi:10.1029/98jd00399

Cited by 160 publications

(133 citation statements)

References 30 publications

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“…Indeed, in regions close to deforestation zones (e.g. Rondonia in Brazil, much of Southeast Asia), the presence of a dryseason burning haze is well documented, and can reduce solar radiation reaching the land surface by more than 15% (Eck et al 1998). In figure 2 we report the temporal trend from the Southern Hemisphere data in Stanhill & Cohen (2001) as this is more likely to mirror the tropical trend than the Northern Hemisphere, which has larger industrialized areas than either the Southern Hemisphere or the tropics.…”

Section: Environmental Changes Over the Past Three Decadesmentioning

confidence: 99%

Fingerprinting the impacts of global change on tropical forests

Lewis

Malhi

Phillips

2004

Phil. Trans. R. Soc. Lond. B

226

252

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Recent observations of widespread changes in mature tropical forests such as increasing tree growth, recruitment and mortality rates and increasing above-ground biomass suggest that 'global change' agents may be causing predictable changes in tropical forests. However, consensus over both the robustness of these changes and the environmental drivers that may be causing them is yet to emerge. This paper focuses on the second part of this debate. We review (i) the evidence that the physical, chemical and biological environment that tropical trees grow in has been altered over recent decades across large areas of the tropics, and (ii) the theoretical, experimental and observational evidence regarding the most likely effects of each of these changes on tropical forests. Ten potential widespread drivers of environmental change were identified: temperature, precipitation, solar radiation, climatic extremes (including El Niñ oSouthern Oscillation events), atmospheric CO 2 concentrations, nutrient deposition, O 3 /acid depositions, hunting, land-use change and increasing liana numbers. We note that each of these environmental changes is expected to leave a unique 'fingerprint' in tropical forests, as drivers directly force different processes, have different distributions in space and time and may affect some forests more than others (e.g. depending on soil fertility). Thus, in the third part of the paper we present testable a priori predictions of forest responses to assist ecologists in attributing particular changes in forests to particular causes across multiple datasets. Finally, we discuss how these drivers may change in the future and the possible consequences for tropical forests.

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Section: Environmental Changes Over the Past Three Decadesmentioning

confidence: 99%

Fingerprinting the impacts of global change on tropical forests

Lewis

Malhi

Phillips

2004

Phil. Trans. R. Soc. Lond. B

226

252

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“…During the dry season in the Amazon region, large amounts of such particles are emitted from biomass burning activities to the atmosphere (Andreae et al, 1991;Yamasoe et al, 2000). Measurements performed in the region showed significant reduction of downward solar total and photosynthetically active irradiance at the surface (Schafer et al, 2002;Procopio et al, 2004;Eck et al, 1998). On the other hand, diffuse fraction of PAR can increase from 19% with a clear atmosphere up to 80% under heavy smoke conditions (Yamasoe et al, 2006 1 ).…”

Section: Introductionmentioning

confidence: 99%

Effect of smoke and clouds on the transmissivity of photosynthetically active radiation inside the canopy

Yamasoe¹,

Randow

Manzi

et al. 2006

Atmos. Chem. Phys.

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Abstract. Biomass burning activities emit high concentrations of aerosol particles to the atmosphere. Such particles can interact with solar radiation, decreasing the amount of light reaching the surface and increasing the fraction of diffuse radiation through scattering processes, and thus has implications for photosynthesis within plant canopies. This work reports results from photosynthetically active radiation (PAR) and aerosol optical depth (AOD) measurements conducted simultaneously at Reserva Biológica do Jaru (Rondonia State, Brazil) during LBA/SMOCC (Large-Scale Biosphere-Atmosphere Experiment in Amazonia/ Smoke, Aerosols, Clouds, Rainfall, and Climate) and RaCCI (Radiation, Cloud, and Climate Interactions in the Amazon during the Dry-to-Wet Transition Season) field experiments from 15 September to 15 November 2002. AOD values were retrieved from an AERONET (Aerosol Robotic Network) radiometer, MODIS (Moderate Resolution Spectroradiometer) and a portable sunphotometer from the United States Department of Agriculture -Forest Service. Significant reduction of PAR irradiance at the top of the canopy was observed due to the smoke aerosol particles layer. This radiation reduction affected turbulent fluxes of sensible and latent heats. The increase of AOD also enhanced the transmission of PAR inside the canopy. As a consequence, the availability of diffuse radiation was enhanced due to light scattering by the aerosol particles. A complex relationship was identified between light availability inside the canopy and net ecosystem exchange (NEE). The results showed that the increase of aerosol optical depth corresponded to an increase of CO 2 uptake by the vegetation. However, for even higher AOD values, the Correspondence to: M. Yamasoe (akemi@model.iag.usp.br) corresponding NEE was lower than for intermediate values.As expected, water vapor pressure deficit (VPD), retrieved at 28 m height inside the canopy, can also affect photosynthesis. A decrease in NEE was observed as VPD increased. Further studies are needed to better understand these findings, which were reported for the first time for the Amazon region under smoky conditions.

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“…The latter is the ratio of the aerosol scattering coef-ficient to the total aerosol extinction coefficient (scattering plus absorption). Many studies have obtained values for w in the visible wavelengths for specific locations and times [Anderson et al, 1999;Devaux et al, 1998;Dubovik et al, 1998Dubovik et al, , 2002Eck et al, 1998;Ogren and Sheridan, 1996;Waggoner et al, 1981;Yu et al, 2000], as these wavelengths are important to climate forcing [Schwartz et al, 1995]. However, less research has been done to determine values of w in the UV wavelengths [Wenny et al, 1998;Kylling et al, 1998].…”

Section: Introductionmentioning

confidence: 99%

Aerosol single scattering albedo retrieved from measurements of surface UV irradiance and a radiative transfer model

et al. 2003

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[1] Aerosol single scattering albedo (w), the ratio of aerosol scattering coefficient to total aerosol extinction coefficient, at UV wavelengths is an important aerosol radiative parameter in determining surface UV irradiance. Surface measurements of total and diffuse UV irradiance in the summer and fall of 1999 at the seven narrowband wavelength channels of an UV multifilter rotating shadowband radiometer (UVMFR-SR) at Black Mountain, N. C., were coupled with a tropospheric ultraviolet radiative transfer model to produce values of w. Its value ranged from 0.65 to 0.91 at 300 nm, 0.71 to 0.96 at 305.5 nm, 0.73 to 0.97 at 311.4 nm, 0.74 to 0.91 at 317.6 nm, 0.76 to 0.96 at 325.4 nm, 0.77 to 0.97 at 332.4 nm, and 0.80 to 0.99 at 368 nm. Error in this procedure decreases with increasing aerosol optical depth (AOD), from ±0.63 at AOD = 0.05 to ±0.04 at AOD = 1.0 averaged over the seven wavelengths. The current values of w have a slightly wider variation than values reported from a previous study at the same site. The lower values of w could indicate that, over the site, preferential absorption of UV radiation by black carbon aerosols could be occurring. More values of w in the UV spectrum will allow for better estimation of this parameter for UV radiative transfer modeling and will lessen error in estimation of surface UV irradiances.

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Measurements of irradiance attenuation and estimation of aerosol single scattering albedo for biomass burning aerosols in Amazonia

Cited by 160 publications

References 30 publications

Fingerprinting the impacts of global change on tropical forests

Fingerprinting the impacts of global change on tropical forests

Effect of smoke and clouds on the transmissivity of photosynthetically active radiation inside the canopy

Aerosol single scattering albedo retrieved from measurements of surface UV irradiance and a radiative transfer model

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