Introduction: Observations and Modeling of the Green Ocean Amazon  (GoAmazon2014/5)

Martin, Scot T.; Artaxo, Paulo; Machado, Luiz A. T.; Manzi, A. O.; Souza, R. A. F. D.; Schumacher, Courtney; Wang, J.; Andreae, Meinrat O.; Barbosa, H. M.; Fan, Jiwen; Fisch, Gilberto; Goldstein, Allen H.; Guenther, Alex; Jimenez, José L.; Pöschl, Ulrich; Dias, M. A. Silva; Smith, James N.; Wendisch, Manfred

doi:10.5194/acp-16-4785-2016

Cited by 277 publications

(412 citation statements)

References 51 publications

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“…Measurements were made at the T3 site of the GoAmazon2014/5 Experiment (25). A PTR-TOF-MS (Ionicon Analytik) equipped with a cold trap was used to measure ISOPOOH and MVK + MACR concentrations.…”

Section: Methodsmentioning

confidence: 99%

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Isoprene photochemistry over the Amazon rainforest

Liu

Brito

Dorris

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

106

165

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Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals (ISOPOO). These radicals can react with hydroperoxyl radicals (HO 2 ) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK + MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4-0.6. This result implies a ratio of the reaction rate of ISOPOO with HO 2 to that with NO of approximately unity. A value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). This abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest.isoprene photochemistry | Amazon | organic hydroperoxides

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Section: Methodsmentioning

confidence: 99%

“…In light of these issues, the present study was undertaken to measure the sum of (1, 2 (25). A major concept of the experiment was to locate a research site (T3) several hours downwind of an urban region (specifically, 70 km west of Manaus, Amazonas, Brazil, a city of 2 million people).…”

Section: Significancementioning

confidence: 99%

Isoprene photochemistry over the Amazon rainforest

Liu

Brito

Dorris

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

106

165

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“…at the T3 site (main GoAmazon site at Manacapuru; see Martin et al, 2016, for a detailed description). The data were averaged to 5 min intervals covering the period from January 2014 to March 2015 (Thalman et al, 2017).…”

Section: Data and Methodsologymentioning

confidence: 99%

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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“…Additionally, two intensive observation periods (IOP) and long-term measurements of the GoAmazon2014/5 experiment took place at several measurement sites in the Amazon Basin, including the ATTO site. More details can be found in Martin et al (2016Martin et al ( , 2017.…”

Section: Ground Measurements Of Aerosol Physical and Chemical Propertmentioning

confidence: 99%

Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

Saturno¹,

Holanda²,

Pöhlker³

et al. 2017

Preprint

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Abstract. The Amazon rain forest is considered a very sensitive ecosystem that could be significantly affected by a changing climate. It is still one of the few places on Earth where the atmosphere in the continent approaches near-pristine conditions for some periods of the year. The Amazon Tall Tower Observatory (ATTO) has been built in central Amazonia to monitor the atmospheric and forest ecosystem conditions. The atmospheric conditions at the ATTO site oscillate between biogenic and biomass burning (BB) dominated states. By using a comprehensive ground-based aerosol measurement setup, we studied the physical and chemical properties of aerosol particles at the ATTO site. This parameterization of å abs as a function of the BC to OA mass ratio was investigated and was found applicable to tropical forest emissions but further investigation is required, especially by segregating fuel types. Additionally, important enhancements of the BC mass absorption cross-section (α abs ) were found over the measurement period. This enhancement could be linked to heavy coating of the BC aerosol particles. In the future, the BC mixing state should be systematically investigated by using different instrumental approaches.

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Introduction: Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5)

Cited by 277 publications

References 51 publications

Isoprene photochemistry over the Amazon rainforest

Isoprene photochemistry over the Amazon rainforest

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

Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

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