The Amazon Boundary Layer Experiment (ABLE 2A): dry season 1985

Harriss, Robert C.; Wofsy, Steven C.; Garstang, Michael; Browell, E. V.; Molion, Luiz Carlos Baldicero; McNeal, Robert J.; Hoell, J. M.; Bendura, R. J.; Beck, Sherwin M.; Garcia, Roberto; Riley, James T.; Snell, R. L.

doi:10.1029/jd093id02p01351

Cited by 163 publications

(63 citation statements)

References 30 publications

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“…The ABLE-2 project consisted of two expeditions: the first in the Amazonian dry season (ABLE-2A) during July-August 1985 and the second in the wet season (ABLE-2B) during April-May 1987 (Harriss et al, 1988. Greco et al (1990) have described the rainfall and kinematics of the central Amazon using GOES (Geostationary Operational Environmental Satellite) imagery, revealing the importance of tropical squall lines in the rainfall regime of the Amazon.…”

Section: Knowledge About Cloud Process In the Amazon Acquired During mentioning

confidence: 99%

“…The evolution of the boundary layer in the Amazon region has been studied during intensive field observations conducted in different subregions in the Amazon Basin, including the Amazon Boundary Layer Experiment (ABLE 2A, 2B; see Harriss et al, 1988Harriss et al, , 1990, the Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS; see Gash et al, 1996), the Large-Scale Biosphere Atmosphere experiment in Amazonia (LBA; see Silva , the Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud-Resolving Modelling and to the Global Precipitation Measurement (CHUVA; Machado et al, 2014) combined with ACRIDICON (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems; , and the Green Ocean Amazon GoAmazon2014/5 . Fisch et al (2004) have indicated that the evolution of the boundary layer in the Amazon is linked to land cover and soil moisture, with a deeper mixed layer in the dry season over deforested areas and a shallower mixed layer over forested areas.…”

Section: The Amazon Forest Climatementioning

confidence: 99%

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Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA

et al. 2018

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Abstract. This study provides an overview of precipitation processes and their sensitivities to environmental conditions in the Central Amazon Basin near Manaus during the GoAmazon2014/5 and ACRIDICON-CHUVA experiments. This study takes advantage of the numerous measurement platforms and instrument systems operating during both campaigns to sample cloud structure and environmental conditions during 2014 and 2015; the rainfall variability among seasons, aerosol loading, land surface type, and topography has been carefully characterized using these data. Differences between the wet and dry seasons were examined from a variety of perspectives. The rainfall rates distribution, total amount of rainfall, and raindrop size distribution (the massweighted mean diameter) were quantified over both seasons.The dry season generally exhibited higher rainfall rates than the wet season and included more intense rainfall periods. However, the cumulative rainfall during the wet season was 4 times greater than that during the total dry season rainfall, as shown in the total rainfall accumulation data. The typical size and life cycle of Amazon cloud clusters (observed by satellite) and rain cells (observed by radar) were examined, as were differences in these systems between the seasons. Moreover, monthly mean thermodynamic and dynamic variables were analysed using radiosondes to elucidate the differences in rainfall characteristics during the wet and dry seasons. The sensitivity of rainfall to atmospheric aerosol loading was discussed with regard to mass-weighted mean diameter and rain rate. This topic was evaluated only durPublished by Copernicus Publications on behalf of the European Geosciences Union. L. A. T. Machado et al.: Overview: Precipitation characteristics and sensitivities to environmental conditionsing the wet season due to the insignificant statistics of rainfall events for different aerosol loading ranges and the low frequency of precipitation events during the dry season. The impacts of aerosols on cloud droplet diameter varied based on droplet size. For the wet season, we observed no dependence between land surface type and rain rate. However, during the dry season, urban areas exhibited the largest rainfall rate tail distribution, and deforested regions exhibited the lowest mean rainfall rate. Airplane measurements were taken to characterize and contrast cloud microphysical properties and processes over forested and deforested regions. Vertical motion was not correlated with cloud droplet sizes, but cloud droplet concentration correlated linearly with vertical motion. Clouds over forested areas contained larger droplets than clouds over pastures at all altitudes. Finally, the connections between topography and rain rate were evaluated, with higher rainfall rates identified at higher elevations during the dry season.

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Section: Knowledge About Cloud Process In the Amazon Acquired During mentioning

confidence: 99%

Section: The Amazon Forest Climatementioning

confidence: 99%

Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA

et al. 2018

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“…Of these regions, the Amazon basin has perhaps been the focus of most international attention, due to the fact that it contains the world's largest tropical rainforest and continues to experience one of the highest rates of deforestation in the world. Measurement campaigns like the Smoke, Cloud, Aerosol and Radiation-Brazil (SCAR-B) experiment and the dry and wet season Amazon Boundary Layer Experiments (ABLE 2A and 2B) (Harriss et al, 1988;Harriss et al, 1990), have sought specifically to improve our understanding of the environmental and climatic effects of biomass burning and background aerosols in this region. As a result, it is now clear that smoke aerosols emitted in Amazonia have a very strong local impact on incoming radiation (Ross et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2003

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Abstract.We investigated the size distribution, scattering and absorption properties of Amazonian aerosols and the optical thickness of the aerosol layer under the pristine background conditions typical of the wet season, as well as during the biomass-burning-influenced dry season. The measurements were made during two campaigns in 1999 as part of the European contribution to the Large-Scale BiosphereAtmosphere Experiment in Amazonia (LBA-EUSTACH). In moving from the wet to the dry season, median particle numbers were observed to increase from values comparable to those of the remote marine boundary layer (∼400 cm −3 ) to values more commonly associated with urban smog (∼4000 cm −3 ), due to a massive injection of submicron smoke particles. Aerosol optical depths at 500 nm increased from 0.05 to 0.8 on average, reaching a value of 2 during the dry season. Scattering and absorption coefficients, measured at 550 nm, showed a concomitant increase from average values of 6.8 and 0.4 Mm −1 to values of 91 and 10 Mm −1 , respectively, corresponding to an estimated decrease in singlescattering albedo from ca. 0.97 to 0.91. The roughly tenfold increase in many of the measured parameters attests to the dramatic effect that extensive seasonal biomass burning (deforestation, pasture cleaning) is having on the composition and properties of aerosols over Amazonia. The potential exists for these changes to impact on regional and global climate through changes to the extinction of solar radiation as well as the alteration of cloud properties.Correspondence to: P. Guyon

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“…Emission and uptake of NO y in the tropics may be particularly important to atmospheric chemistry. Because photochemical reactions proceed most efficiently in the low-latitude humid tropics (Harriss et al 1988), and since tropical areas are being developed for human use at a rapid rate, it is important to measure intact, undisturbed tropical systems to allow us to understand potential impacts on the atmosphere (Crutzen 1985;McElroy and Wofsy 1986). Additionally, Matson et al (1998) have suggested atmospheric N deposition will increase in tropical forests, which could lead to increased soil NO emissions (Hall and Matson 1999).…”

Section: Introductionmentioning

confidence: 99%

Leaf uptake of nitrogen dioxide (NO2) in a tropical wet forest: implications for tropospheric chemistry

et al. 2001

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Tropical forest soils are known to emit large amounts of reactive nitrogen oxide compounds, often referred to collectively as NO y (NO y = NO + NO 2 + HNO 3 + organic nitrates). Plants are known to assimilate and emit NO y and it is therefore likely that plant canopies affect the atmospheric concentration of reactive nitrogen compounds by assimilating or emitting some fraction of the soil-emitted NO y . It is crucial to understand the magnitude of the canopy effects and the primary environmental and physiological controls over NO y exchange in order to accurately quantify regional NO y inventories and parameterize models of tropospheric photochemistry. In this study we focused on nitrogen dioxide (NO 2 ), which is the component of NO y that most directly catalyzes the chemistry of O 3 dynamics, one of the most abundant oxidative species in the troposphere, and which has been reported as the NO y species that is most readily exchanged between plants and the atmosphere. Leaf chamber measurements of NO 2 flux were measured in 25 tree species growing in a wet tropical forest in the Republic of Panama. NO 2 was emitted to the atmosphere at ambient NO 2 concentrations below 0.53-1.60 ppbv (the NO 2 compensation point) depending on species, with the highest rate of emission being 50 pmol m -2 s -1 at <0.1 ppbv. NO 2 was assimilated by leaves at ambient NO 2 concentrations above the compensation point, with the maximum observed uptake rate being 1,550 pmol m -2 s -1 at 5 ppbv. No seasonal variation in leaf NO 2 flux was observed in this study and leaf emission and uptake appeared to be primarily controlled by leaf nitrogen and stomatal conductance, respectively. When scaled to the entire canopy, soil NO emission rates to the atmosphere were estimated to be maximally altered ±19% by the overlying canopy.

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The Amazon Boundary Layer Experiment (ABLE 2A): dry season 1985

Cited by 163 publications

References 30 publications

Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA

Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA

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

Leaf uptake of nitrogen dioxide (NO2) in a tropical wet forest: implications for tropospheric chemistry

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