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Air pollution is one of the main environmental problems in the metropolitan area of Sao Paulo (MASP) in Brazil, with frequent exceedances of air quality standards. Occasionally, the exceedance events last many days, resulting in continuous exposure to concentrations above the standards, with impacts to human health. In this air pollution long-term study, a method was developed to identify persistent exceedance events (PEE) of particulate matter (PM10) and ozone (O3) and associated surface weather patterns. Between 2005 and 2017, 119 PEE were identified, with exceedances occurring simultaneously in at least 50% of monitoring stations along 3 to 14 consecutive days. Median PM10 and O3 concentrations increased by 60% during the events. Mean fields of sea level pressure from global reanalysis data revealed the influence of high-pressure systems and pre-frontal conditions. PM10 events were frequent in austral winter and mostly driven by anomalous atmospheric circulation with a wind change to northwest. On the other hand, O3 events were common in the spring, associated with higher positive anomalies of temperature and solar radiation. Overall, results show that PEE span a regional scale, differing from ordinary exceedance events that can be driven by local conditions. Policy makers should be aware of the frequency of PEE in the development of mitigation measures against the exposure to harmful levels of air pollutants. The concept of PEE can be applied to other metropolitan areas and may support the development of data-driven air quality predictive models based on current or forecasted weather conditions.

The Saharan Air Layer is a mass of hot, dry air laden with dust that forms over the Sahara and moves towards the Atlantic Ocean. This air mass contains soil dust particles emitted by the action of winds on the African continent. Between June and August, the large-scale patterns of wind circulation transport dust from the Sahara across the tropical North Atlantic Ocean,affecting parts of the Caribbean, Central America, Mexico, even some regions of the United States, and the Mediterranean and Southern Europe. Between December and April, wind circulation patterns facilitate dust transportation from the Sahara to the northern parts of South America and the Amazon. This dust transportation a phenomenon of interest to geosciencesand public health because of the potential health impacts of dust dispersion and circulation in the atmosphere. Thus, we assessed the relationship between exposure to Saharan dust (SahD) and its implications for human health in the Americas. We performed a nonsystematic review in the PubMed, Google Scholar, EMBASE, and Scielo databases of studies published between 2000 and 2020 in Portuguese, English, French, or Spanish using the search words “Saharan dust,” or “mineral dust,” or “desert dust,” and “human health.” The available direct air pollutants measurements indicate that the pollution level in the cities affected on a constant and prolonged basis is high versus acceptable standards. Further, this review also showed that the negative health effects of SahD are sparsely studied in the Americas.

A situação da Floresta Amazônica está em constante debate na comunidade científica devido a sua relevância tanto no contexto climático quanto na biodiversidade nacional. A análise dos dados coletados na região é vista como poderoso recurso não somente para identificar e mitigar a ação antrópica, mas também para entender o complexo ecossistema existente. Este artigo apresenta uma análise seguindo os princípios FAIR de dois bancos de dados disponíveis na internet e que possuem dados relacionados a medições climáticas da Floresta Amazônica.

Air pollution is one the main environmental problems in urban areas likethe Metropolitan Area of São Paulo (MASP) in Brazil, where millions ofinhabitants are exposed to pollution concentrations above the standards,with potential health impacts. Exposure is unequal throughout MASP,relying on the dynamics of local emission sources interplaying with weatherand climate in a regional scale. The ABC region — ABC standing for SantoAndré, São Bernardo do Campo and São Caetano do Sul, the cities thearea originally comprised of — is MASP’s largest industrial center, sitting inits southeast border, and encloses environmental protection areas. Thatleads to a unique emission profile that differ from the metropolis center.This study aims to characterize the variability of atmospheric pollutantsin the ABC region in 2015, investigating possible sources and associationswith surface meteorological conditions. Multivariate statistical analyseswere applied to data from seven air quality monitoring stations andsurface meteorological variables. Results show that São Bernardo doCampo stood out, with O3 concentrations 20% higher (43±19 μg.m-3)than the other sites, while São Caetano do Sul had the highest annualmean PM10 concentrations (39±19 μg.m-3), mostly related to vehicularemissions. Relative humidity was negatively correlated with primarypollutants, while temperature and radiation correlated with O3. Unusuallyhigh O3 concentrations were observed in January of 2015, concomitantwith negative anomalies of precipitation and relative humidity, likelyassociated with the 2014/2015 summer drought event in SoutheastBrazil. Overall, results show that local emission sources significantlyimpact air pollution loading and its diurnal variability, particularly in thecase of primary pollutants. Climate modulates the seasonal concentrationvariability, and regional scale weather phenomena may impact air qualityconditions. To reach concentration standards everywhere, policy makersmust be aware of processes occurring in different spatial scales thatdetermine air quality. A poluição atmosférica é um dos principais problemas ambientais em áreasurbanas como a Região Metropolitana de São Paulo (RMSP), no Brasil, ondemilhões de habitantes estão expostos a concentrações acima dos padrões,com potenciais impactos à saúde. A exposição à poluição atmosférica édesigual na RMSP, dependendo da dinâmica de fontes emissoras locais eda influência do tempo e do clima em escala regional. A região do ABC —sigla originada a partir das iniciais de suas cidades originais: Santo André,São Bernardo do Campo e São Caetano do Sul — é o maior centro industrialda RMSP, localizada em sua fronteira sudeste, e inclui áreas de proteçãoambiental. Essas características resultam em um perfil de emissõessingular, que difere do centro da metrópole. Este estudo visa caracterizara variabilidade na concentração de poluentes atmosféricos na região doABC em 2015, investigando possíveis fontes e associações a condiçõesmeteorológicas de superfície. Análises estatísticas multivariadas foramaplicadas a dados de qualidade do ar de sete estações de monitoramento evariáveis meteorológicas de superfície. São Bernardo do Campo se destacou,com concentrações de O3 20% maiores (43±19 μg.m-3) do que as outrasestações, enquanto São Caetano do Sul apresentou a maior média anualde PM10 (39±19 μg.m-3), relacionada principalmente a emissões veiculares.A umidade relativa apresentou correlação negativa com os poluentesprimários, enquanto a temperatura e a radiação se correlacionaram aoO3. Elevadas concentrações de O3 foram atipicamente observadas emjaneiro de 2015 (59±19 μg.m-3), simultaneamente a anomalias negativasde precipitação e umidade relativa, possivelmente associadas ao evento deseca no Sudeste do Brasil no verão de 2014/2015. Os resultados mostramque fontes emissoras locais podem impactar significativamente a carga depoluição e sua variabilidade diurna, especialmente no caso de poluentesprimários. O clima modula a variabilidade sazonal das concentrações, efenômenos meteorológicos de escala regional podem impactar a qualidadedo ar. Para atingir os padrões de concentração em toda a parte, o poderpúblico deve ficar atento aos processos que ocorrem em diferentes escalasespaciais e que determinam a qualidade do ar.

New particle formation (NPF), referring to the nucleation of molecular clusters and their subsequent growth into the cloud condensation nuclei (CCN) size range, is a globally significant and climate-relevant source of atmospheric aerosols. Classical NPF exhibiting continuous growth from a few nanometers to the Aitken mode around 60–70 nm is widely observed in the planetary boundary layer (PBL) around the world but not in central Amazonia. Here, classical NPF events are rarely observed within the PBL, but instead, NPF begins in the upper troposphere (UT), followed by downdraft injection of sub-50 nm (CN) particles into the PBL and their subsequent growth. Central aspects of our understanding of these processes in the Amazon have remained enigmatic, however. Based on more than 6 years of aerosol and meteorological data from the Amazon Tall Tower Observatory (ATTO; February 2014 to September 2020), we analyzed the diurnal and seasonal patterns as well as meteorological conditions during 254 of such Amazonian growth events on 217 event days, which show a sudden occurrence of particles between 10 and 50 nm in the PBL, followed by their growth to CCN sizes. The occurrence of events was significantly higher during the wet season, with 88 % of all events from January to June, than during the dry season, with 12 % from July to December, probably due to differences in the condensation sink (CS), atmospheric aerosol load, and meteorological conditions. Across all events, a median growth rate (GR) of 5.2 nm h−1 and a median CS of 1.1 × 10−3 s−1 were observed. The growth events were more frequent during the daytime (74 %) and showed higher GR (5.9 nm h−1) compared to nighttime events (4.0 nm h−1), emphasizing the role of photochemistry and PBL evolution in particle growth. About 70 % of the events showed a negative anomaly of the equivalent potential temperature (Δθe′) – as a marker for downdrafts – and a low satellite brightness temperature (Tir) – as a marker for deep convective clouds – in good agreement with particle injection from the UT in the course of strong convective activity. About 30 % of the events, however, occurred in the absence of deep convection, partly under clear-sky conditions, and with a positive Δθe′ anomaly. Therefore, these events do not appear to be related to downdraft transport and suggest the existence of other currently unknown sources of sub-50 nm particles.

Biomass burning emissions in Amazonia change the atmospheric composition and aerosol properties during the dry season. We investigated fine-mode aerosol chemical composition and optical properties with an intensive field experiment in the dry-to-wet season transition in 2018 in Southwestern Amazonia. Aerosol composition and physical properties were measured using ACSMs, aethalometers, nephelometers, SMPSs, and CPCs. PM1 mass concentrations showed a mean value of 12.4 ± 10.1 μg m−3. Organic matter was the major constituent of PM1, contributing more than 75%, whereas black carbon (BC) contributed ∼15%, and inorganics were less than 10%. The organic fraction of PM1 was apportioned by positive-matrix factorization (PMF), resolving 4 organic aerosol (OA) factors: two oxygenated OAs (OOA-1 and OOA-2), one hydrocarbon-like (HOA), and one biomass burning OA (BBOA). A low single scattering albedo (637 nm) of 0.77 ± 0.08 was observed, suggesting a significant absorption material. BC and brown carbon (BrC) contributions to the absorption coefficient (470 nm) were retrieved, and BrC corresponded, on average, to 20% of total absorption. The mass scattering (MSE) and absorption efficiencies (MAE) of PM1 particles were determined by multilinear regression (MLR), using the PMF factors as predictor variables. Overall, organic aerosols showed significant light absorption in the UV-vis wavelength range and strong spectral dependence indicating the presence of organic species that act as BrC, predominantly associated with biomass burning OAs. Our results emphasize the need for a better understanding of links between aerosol composition and optical properties, including the absorption spectra of BrC in the Amazon.

New particle formation (NPF), referring to the nucleation of molecular clusters and their subsequent growth into the cloud condensation nuclei (CCN) size range, is a globally significant and climate-relevant source of atmospheric aerosols. Classical NPF exhibiting continuous growth from a few nanometers to the Aitken mode around 60–70 nm is widely observed in the planetary boundary layer (PBL) around the world, but not in central Amazonia. Here, classical NPF events are rarely observed in the PBL, but instead, NPF begins in the upper troposphere (UT), followed by downdraft injection of sub-50 nm (CN

O ozônio (O3) é um dos poluentes responsáveis pela deterioração da qualidade do ar em áreas urbanas. Trata-se de um poluente secundário, formado na atmosfera a partir de reações fotoquímicas, sendo que sua produção depende tanto de fatores meteorológicos quanto de fatores químicos. Este trabalho tem por objetivo analisar a variabilidade interanual das concentrações de O3 na região metropolitana de São Paulo entre 2005 e 2015, isolando a contribuição de fatores químicos, através da aplicação do filtro Kolmogorov–Zurbenko. Os resultados mostram que a variabilidade das condições meteorológicas explicou de 39 a 52% da variância das concentrações de O3 no período de estudo. Picos de concentração de O3 na componente de longo prazo foram atribuídos majoritariamente a fatores químicos, associados a mudanças no padrão de emissão de precursores. Nos anos em que foram observadas altas concentrações de O3 houve um aumento no consumo de gasolina em relação a etanol. Ozone (O3) is one of the main pollutants that contribute to air quality deterioration in urban areas. It is a secondary pollutant, produced in the atmosphere by photochemical reactions, in a way that its formation depends both on meteorological and chemical factors. This work aims to analyze the interannual variability of O3 concentrations at the Sao Paulo metropolitan region between 2005 and 2015, isolating the contribution of chemical factors using the Kolmogorov-Zurbenko filter. Results indicate that the variability of meteorological conditions explained from 39 to 52% of O3 concentration variance during the study period. O3 concentration peaks in the long-term time series component were mainly associated with chemical factors, associated with changes in the emission pattern of precursors. Years with high O3 concentrations occurred simultaneously with increases on the gasoline usage relative to ethanol.

Existe na comunidade de ciências atmosféricas, uma carência pelo desenvolvimento de ferramentas para visualização de dados que integrem diversos conjuntos de informações relacionadas às condições meteorológicas e ambientais. Esse trabalho tem como foco a discussão de técnicas de visualização e gerenciamento de dados ambientais orientadas por uma metodologia de análise ordenada em níveis temporais (níveis de ano, mês e dia). Foi desenvolvida uma ferramenta computacional que permitiu a integração dos níveis de análise, facilitando tirada de conclusões. Para a implementação de tal ferramenta, fez-se uso de recursos oferecidos por bibliotecas do Python.

A poluição do ar é um dos principais problemas enfrentados em regiõesurbanas, e sua percepção pela população é fundamental para a mitigaçãodo problema. Este estudo analisou a percepção da poluição do ar por doisgrupos de comerciários do município de Diadema: um atuante no centro dacidade, em uma via de intenso tráfego, e outro atuante na periferia (bairro).Os resultados demonstram que os entrevistados têm clara percepção dapoluição do ar (90% no centro e 70% no bairro) e identificaram corretamenteseu principal agente, a emissão veicular. Entretanto, a maioria dosentrevistados (65%) não se identificou como causa do problema. A percepçãodos entrevistados sobre a evolução da qualidade do ar foi coerente com dadosde concentração dos poluentes. Vale ressaltar a divergência encontradaentre a percepção dos comerciários e os índices oficiais de qualidade do ar.Não houve diferenças significativas entre as percepções dos comerciários docentro e do bairro.

Localizada na floresta amazônica, a cidade de Manaus é considerada um laboratório ideal para o estudo dos efeitos da ação antrópica no clima e nos ecossistemas terrestres em uma floresta tropical. O projeto GOAmazon 2014/15 coletou dados atmosféricos de poluentes e variáveis meteorológicas na região. Neste projeto, buscou-se realizar a coleta e o tratamento dos dados, comparando métodos de interpolação espacial, como linear, por splines e nearest neighbor, e selecionando o com o melhor desempenho para estabelecer um mapeamento das variáveis na região vento abaixo da cidade de Manaus e agregar conhecimentos sobre pluma de Manaus e seus impactos no ambiente, que possibilitarão o desenvolvimento de novos experimentos.

Air pollution is one of the main environmental problems in large urban centers, affecting people’s health and impacting quality of life. The Metropolitan Area of Sao Paulo (MASP) presents frequent exceedances of air-quality standards in inhalable particulate matter (PM10), a consequence of pollutant emissions modulated by meteorological conditions. This study aims to identify and characterize PM10persistent exceedance events (PEE) inthe MASP between 2005 and 2017, relating them to meteorological conditions. The criteria used to select the events were: (i) events that occurred in at least 50% of the air-quality monitoring stations chosen for this study and, (ii) among the events that met the first criterion, those with a duration equal to or greater than five days, which correspond to the 80% percentile of the event duration distribution. A total 71 persistent episodes of exceedance were selected. The results show that the exceedance of PM10 lasted up to 14 consecutive days and was predominant in the austral winter, accompanied by an increase in maximum temperature (T), a decrease in wind speed (WS) and relative humidity (RH), and a wind direction predominantly from the northwest during the peak concentration of the pollutant. On average, a concentration increase of 60% was observed at the peak of the PEE.

The Amazon Rainforest is highlighted by the global community both for its extensive vegetation cover that constantly suffers the effects of anthropic action and for its substantial biodiversity. This dataset presents data of meteorological variables from the Amazon Rainforest region with a spatial resolution of 0.001° in latitude and longitude, resulting from an interpolation process. The original data were obtained from the GoAmazon 2014/5 project, in the Atmospheric Radiation Measurement (ARM) repository, and then processed through mathematical and statistical methods. The dataset presented here can be used in experiments in the field of Data Science, such as training models for predicting climate variables or modeling the distribution of species.

This review study aimed to determine the relationship between exposure to smoke from biomass burning in the Amazon rain forest and its implications on human health in that region in Brazil. A nonsystematic review was carried out by searching PubMed, Google Scholar, SciELO, and EMBASE databases for articles published between 2005 and 2021, either in Portuguese or in English, using the search terms “biomass burning” OR “Amazon” OR “burned” AND “human health.” The review showed that the negative health effects of exposure to smoke from biomass burning in the Amazon have been poorly studied in that region. There is an urgent need to identify effective public health interventions that can help improve the behavior of vulnerable populations exposed to smoke from biomass burning, reducing morbidity and mortality related to that exposure. RESUMO Este estudo de revisão teve como objetivo determinar a relação entre a exposição à fumaça da queima de biomassa na Floresta Amazônica e suas implicações para a saúde humana nessa região do Brasil. Foi realizada uma revisão não sistemática por meio de buscas nas bases de dados PubMed, Google Scholar, SciELO e EMBASE de artigos publicados entre 2005 e 2021, em português ou inglês, utilizando os termos de busca “biomass burning” OU “Amazon” OU “burned” E “human health”. A revisão mostrou que os efeitos negativos para a saúde resultantes da exposição à fumaça da queima de biomassa na Amazônia foram pouco estudados na região. Há uma necessidade urgente de identificar intervenções efetivas de saúde pública que possam ajudar a melhorar o comportamento das populações vulneráveis expostas à fumaça da queima de biomassa, reduzindo a morbimortalidade relacionada a essa exposição.

The decline in Amazonian deforestation rates and biomass burning activity (2001–2012) has been shown to reduce air pollutant emissions (e.g., aerosols) and improve regional air quality. However, in the Cerrado region (savannah grasslands in northeastern Brazil), satellite observations reveal increases in fire activity and tropospheric column nitrogen dioxide (an ozone precursor) during the burning season (August‐October, 2005–2016), which have partially offset these air quality benefits. Simulations from a 3‐D global chemistry transport model (CTM) capture this increase in NO2 with a surface increase of ~1 ppbv per decade. As there are limited long‐term observational tropospheric ozone records, we utilize the well‐evaluated CTM to investigate changes in ozone. Here, the CTM suggests that Cerrado region surface ozone is increasing by ~10 ppbv per decade. If left unmitigated, these positive fire‐sourced ozone trends will substantially increase the regional health risks and impacts from expected future enhancements in South American biomass burning activity under climate change.

With the mass adoption of data analysis in several scientific fields such as climatology, medicine, astronomy and astrophysics, the availability of an appropriate analytics infrastructure has becom...

Consistent long-term estimates of fire emissions are important to understand the changing role of fire in the global carbon cycle and to assess the relative importance of humans and climate in shaping fire regimes. However, there is limited information on fire emissions from before the satellite era. We show that in the Amazon region, including the Arc of Deforestation and Bolivia, visibility observations derived from weather stations could explain 61% of the variability in satellite-based estimates of bottom-up fire emissions since 1997 and 42% of the variability in satellite-based estimates of total column carbon monoxide concentrations since 2001. This enabled us to reconstruct the fire history of this region since 1973 when visibility information became available. Our estimates indicate that until 1987 relatively few fires occurred in this region and that fire emissions increased rapidly over the 1990s. We found that this pattern agreed reasonably well with forest loss data sets, indicating that although natural fires may occur here, deforestation and degradation were the main cause of fires. Compared to fire emissions estimates based on Food and Agricultural Organization's Global Forest and Resources Assessment data, our estimates were substantially lower up to the 1990s, after which they were more in line. These visibility-based fire emissions data set can help constrain dynamic global vegetation models and atmospheric models with a better representation of the complex fire regime in this region.

We use the GLOMAP global aerosol model evaluated against observations of surface particulate matter (PM2.5) and aerosol optical depth (AOD) to better understand the impacts of biomass burning on tropical aerosol over the period 2003 to 2011. Previous studies report a large underestimation of AOD over regions impacted by tropical biomass burning, scaling particulate emissions from fire by up to a factor of 6 to enable the models to simulate observed AOD. To explore the uncertainty in emissions we use three satellite-derived fire emission datasets (GFED3, GFAS1 and FINN1). In these datasets the tropics account for 66–84 % of global particulate emissions from fire. With all emission datasets GLOMAP underestimates dry season PM2.5 concentrations in regions of high fire activity in South America and underestimates AOD over South America, Africa and Southeast Asia. When we assume an upper estimate of aerosol hygroscopicity, underestimation of AOD over tropical regions impacted by biomass burning is reduced relative to previous studies. Where coincident observations of surface PM2.5 and AOD are available we find a greater model underestimation of AOD than PM2.5, even when we assume an upper estimate of aerosol hygroscopicity. Increasing particulate emissions to improve simulation of AOD can therefore lead to overestimation of surface PM2.5 concentrations. We find that scaling FINN1 emissions by a factor of 1.5 prevents underestimation of AOD and surface PM2.5 in most tropical locations except Africa. GFAS1 requires emission scaling factor of 3.4 in most locations with the exception of equatorial Asia where a scaling factor of 1.5 is adequate. Scaling GFED3 emissions by a factor of 1.5 is sufficient in active deforestation regions of South America and equatorial Asia, but a larger scaling factor is required elsewhere. The model with GFED3 emissions poorly simulates observed seasonal variability in surface PM2.5 and AOD in regions where small fires dominate, providing independent evidence that GFED3 underestimates particulate emissions from small fires. Seasonal variability in both PM2.5 and AOD is better simulated by the model using FINN1 emissions. Detailed observations of aerosol properties over biomass burning regions are required to better constrain particulate emissions from fires.

The Sao Paulo Metropolitan Area is a unique case worldwide due to the extensive use of biofuel, particularly ethanol, by its large fleet of nearly 8 million cars. Based on source apportionment analysis of Organic Aerosols in downtown Sao Paulo, and using ethanol as tracer of passenger vehicles, we have identified primary emissions from light-duty-vehicles (LDV) and heavy-duty-vehicles (HDV), as well as secondary process component. Each of those factors mirror a relevant primary source or secondary process in this densely occupied area. Using those factors as predictors in a multiple linear regression analysis of a wide range of pollutants, we have quantified the role of primary LDV or HDV emissions, as well as atmospheric secondary processes, on air quality degradation. Results show a significant contribution of HDV emissions, despite contributing only about 5% of vehicles number in the region. The latter is responsible, for example, of 40% and 47% of benzene and black carbon atmospheric concentration, respectively. This work describes an innovative use of biofuel as a tracer of passenger vehicle emissions, allowing to better understand the role of vehicular sources on air quality degradation in one of most populated megacities worldwide.

In the Amazon basin, particles containing mixed sodium salts are routinely observed and are attributed to marine aerosols transported from the Atlantic Ocean. Using chemical imaging analysis, we show that, during the wet season, fungal spores emitted by the forest biosphere contribute at least 30% (by number) to sodium salt particles in the central Amazon basin. Hydration experiments indicate that sodium content in fungal spores governs their growth factors. Modeling results suggest that fungal spores account for ~69% (31–95%) of the total sodium mass during the wet season and that their fractional contribution increases during nighttime. Contrary to common assumptions that sodium-containing aerosols originate primarily from marine sources, our results suggest that locally-emitted fungal spores contribute substantially to the number and mass of coarse particles containing sodium. Hence, their role in cloud formation and contribution to salt cycles and the terrestrial ecosystem in the Amazon basin warrant further consideration., Salt particles in the Amazon basin are typically attributed to marine aerosols transported from the Atlantic Ocean. Here the authors show the potential importance of fungal spores as a source of sodium-salt particles in the Amazon rainforest.

As part of the Observations and Modeling of the Green Ocean Amazon (GoAmazon 2014/5) Experiment, detailed aerosol and trace gas measurements were conducted near Manaus, a metropolis located in the central Amazon Basin. Measurements of aerosol particles and trace gases were done downwind Manaus at the sites T2 (Tiwa Hotel) and T3 (Manacapuru), at a distance of 8 and 70 km from Manaus, respectively. Based on in-plume measurements closer to Manaus (site T2), the chemical signatures of city emissions were used to improve the interpretation of pollutant levels at the T3 site. We derived chemical and physical properties for the city's atmospheric emission ensemble, taking into account only air masses impacted by the Manaus plume at both sites, during the wet and dry season Intensive Operating Periods (IOPs). At T2, average concentrations of aerosol number (CN), CO and SO2 were 5500 cm−3 (between 10 and 490 nm), 145 ppb and 0.60 ppb, respectively, with a typical ratio ΔCN/ΔCO of 60–130 particles cm−3 ppb−1. The aerosol scattering (at RH < 60%) and absorption at 637 nm at T2 ranged from 10 to 50 M m−1 and 5–10 M m−1, respectively, leading to a mean single scattering albedo (SSA) of 0.70. In addition to identifying periods dominated by Manaus emissions at both T2 and T3, the plume transport between the two sampling sites was studied using back trajectory calculations. Results show that the presence of the Manaus plume at site T3 was important mainly during the daytime and at the end of the afternoons. During time periods directly impacted by Manaus emissions, an average aerosol number concentration of 3200 cm−3 was measured at T3. Analysis of plume evolution between T2 and T3 indicates a transport time of 4–5 h. Changes of submicron organic and sulfate aerosols ratios relative to CO (ΔOA/ΔCO and ΔSO4/ΔCO, respectively) indicate significant production of secondary organic aerosol (SOA), corresponding to a 40% mass increase in OA and a 30% in SO4 mass concentration. Similarly, during air mass arrival at T3 the SSA increased to 0.83 from 0.70 at T2, mainly associated with an increase in organic aerosol concentration. Aerosol particle size distributions show a strong decrease in the Aitken nuclei mode (10–100 nm) during the transport from T2 to T3, in particular above 30 nm, as a result of efficient coagulation processes into larger particles. A decrease of 30% in the particle number concentration and an increase of about 50 nm in geometric mean diameter were observed from T2 to T3 sites. The study of the evolution of aerosol properties downwind of the city of Manaus improves our understanding of how coupling of anthropogenic and biogenic sources may be impacting the sensitive Amazonian atmosphere. © 2018 The Authors

The physical state of atmospheric particulate matter affects its growth and reactivity, which can affect climate. Measurements of particle rebound reveal that particulate matter over the Amazon forest is usually liquid during wet and dry seasons.

The HadGEM2 earth system climate model was used to assess the impact of biomass burning on surface ozone concentrations over the Amazon forest and its impact on vegetation, under present-day climate conditions. Here we consider biomass burning emissions from wildfires, deforestation fires, agricultural forest burning, and residential and commercial combustion. Simulated surface ozone concentration is evaluated against observations taken at two sites in the Brazilian Amazon forest for years 2010 to 2012. The model is able to reproduce the observed diurnal cycle of surface ozone mixing ratio at the two sites, but overestimates the magnitude of the monthly averaged hourly measurements by 5–15 ppb for each available month at one of the sites. We vary biomass burning emissions over South America by ±20, 40, 60, 80 and 100% to quantify the modelled impact of biomass burning on surface ozone concentrations and ozone damage on vegetation productivity over the Amazon forest. We used the ozone damage scheme in the "high" sensitivity mode to give an upper limit for this effect. Decreasing South American biomass burning emissions by 100% (i.e. to zero) reduces surface ozone concentrations (by about 15 ppb during the biomass burning season) and suggests a 15% increase in monthly mean net primary productivity averaged over the Amazon forest, with local increases up to 60%. The simulated impact of ozone damage from present-day biomass burning on vegetation productivity is about 230 TgC yr−1. Taking into account that uncertainty in these estimates is substantial, this ozone damage impact over the Amazon forest is of the same order of magnitude as the release of carbon dioxide due to fire in South America; in effect it potentially doubles the impact of biomass burning on the carbon cycle.

The Amazon Basin is a unique region to study atmospheric aerosols, given their relevance for the regional hydrological cycle and the large uncertainty of their sources. Multi-year datasets are crucial when contrasting periods of natural conditions and periods influenced by anthropogenic emissions. In the wet season, biogenic sources and processes prevail, and the Amazonian atmospheric composition resembles preindustrial conditions. In the dry season, the basin is influenced by widespread biomass burning emissions. This work reports multi-year observations of high time resolution submicrometer (10–600 nm) particle number size distributions at a rain forest site in Amazonia (TT34 tower, 60 km NW from Manaus city), between 2008 and 2010 and 2012 and 2014. The median particle number concentration was 403 cm−3 in the wet season and 1254 cm−3 in the dry season. The Aitken mode ( ∼  30–100 nm in diameter) was prominent during the wet season, while the accumulation mode ( ∼  100–600 nm in diameter) dominated the particle size spectra during the dry season. Cluster analysis identified groups of aerosol number size distributions influenced by convective downdrafts, nucleation events and fresh biomass burning emissions. New particle formation and subsequent growth was rarely observed during the 749 days of observations, similar to previous observations in the Amazon Basin. A stationary 1-D column model (ADCHEM – Aerosol Dynamics, gas and particle phase CHEMistry and radiative transfer model) was used to assess the importance of the processes behind the observed diurnal particle size distribution trends. Three major particle source types are required in the model to reproduce the observations: (i) a surface source of particles in the evening, possibly related to primary biological emissions; (ii) entrainment of accumulation mode aerosols in the morning; and (iii) convective downdrafts transporting Aitken mode particles into the boundary layer mostly during the afternoon. The latter process has the largest influence on the modeled particle number size distributions. However, convective downdrafts are often associated with rain and, thus, act as both a source of Aitken mode particles and a sink of accumulation mode particles, causing a net reduction in the median total particle number concentrations in the surface layer. Our study shows that the combination of the three mentioned particle sources is essential to sustain particle number concentrations in Amazonia.

Size-resolved measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations and hygroscopicity were conducted at the remote Amazon Tall Tower Observatory (ATTO) in the central Amazon Basin over a full seasonal cycle (Mar 2014–Feb 2015). In a companion part 1 paper, we presented an in-depth CCN characterization based on annually as well as seasonally averaged time intervals and discuss different parametrization strategies to represent the Amazonian CCN cycling in modelling studies (M. Pohlker et al., 2016b). The present part 2 study analyzes the aerosol and CCN variability in original time resolution and, thus, resolves aerosol advection and transformation for the following case studies, which represent the most characteristic states of the Amazonian atmosphere: 1. Near-pristine (NP) conditions, defined as the absence of detectable black carbon ( −3 ), showed their highest occurrence (up to 30 %) in the wet season (i.e., Mar–May). On average, the NP episodes are characterized by a bimodal aerosol size distribution (strong Aitken mode: D Ait = 70 nm, N Ait = ~ 200 cm −3 vs. weaker accumulation mode: D acc = 170 nm, N acc = ~ 60 cm −3 ), a mostly organic particle composition, and relatively low hygroscopicity levels (κ Ait = 0.12 vs. κ acc = 0.18). The NP CCN efficiency spectrum shows that the CCN population is sensitive to changes in supersaturation ( S ) over a wide S range. 2. Long-range transport (LRT) conditions frequently mix Saharan dust, African combustion smoke, and sea spray aerosols into the Amazonian wet season atmosphere. The LRT episodes (i.e., Feb–Apr) are characterized by an accumulation mode dominated size distribution ( D Ait = 80 nm, N Ait = 120 cm −3 vs. D acc = 180 nm, N acc = 300 cm −3 ), a clearly increased abundance of dust and salt compounds, and relatively high hygroscopicity levels (κ Ait = 0.18, κ acc = 0.34). The LRT CCN efficiency spectrum shows that the CCN population is highly sensitive to changes in S in the low S regime. 3. Biomass burning (BB) conditions dominate the Amazonian dry season. A selected characteristic BB episode shows a very strong accumulation mode ( D Ait = 70 nm, N Ait = ~ 140 cm −3 vs. D acc = 170 nm, N acc = ~ 3400 cm −3 ), particles with very high organic fractions (> 90 %), and correspondingly low hygroscopicity levels (κ Ait = 0.14, κ acc = 0.17). The BB CCN efficiency spectrum shows that the CCN population is highly sensitive to changes in S in the low S regime. 4. Mixed pollution conditions show the superposition of African (i.e., volcanic) and Amazonian (i.e., biomass burning) aerosol emissions during the dry season. The African aerosols showed a broad monomodal distribution ( D = 130 nm, N = ~ 1300 cm −3 ), with very high sulfate fractions (20 %), and correspondingly high hygroscopicity (κ Ait = 0.14, κ acc = 0.22). This was superimposed by fresh smoke from nearby fires with one strong mode ( D = 113 nm, N acc = ~ 2800 cm −3 ), an organic-dominated aerosol, and sharply decreased hygroscopicity (κ Ait = 0.10, κ acc = 0.20). These conditions underline the rapidly changing pollution regimes with clear impacts on the aerosol and CCN properties. Overall, this study provides detailed insights into the CCN cycling in relation to aerosol-cloud interaction in the vulnerable and climate-relevant Amazon region. The detailed analysis of aerosol and CCN key properties and particularly the extracted CCN efficiency spectra with the associated fit parameters provide a basis for an in-depth analysis of aerosol-cloud interaction in the Amazon and beyond.

The Observations and Modeling of the Green Ocean Amazon 2014–2015 (GoAmazon2014/5) experiment took place around the urban region of Manaus in central Amazonia across 2 years. The urban pollution plume was used to study the susceptibility of gases, aerosols, clouds, and rainfall to human activities in a tropical environment. Many aspects of air quality, weather, terrestrial ecosystems, and climate work differently in the tropics than in the more thoroughly studied temperate regions of Earth. GoAmazon2014/5, a cooperative project of Brazil, Germany, and the United States, employed an unparalleled suite of measurements at nine ground sites and on board two aircraft to investigate the flow of background air into Manaus, the emissions into the air over the city, and the advection of the pollution downwind of the city. Herein, to visualize this train of processes and its effects, observations aboard a low-flying aircraft are presented. Comparative measurements within and adjacent to the plume followed the emissions of biogenic volatile organic carbon compounds (BVOCs) from the tropical forest, their transformations by the atmospheric oxidant cycle, alterations of this cycle by the influence of the pollutants, transformations of the chemical products into aerosol particles, the relationship of these particles to cloud condensation nuclei (CCN) activity, and the differences in cloud properties and rainfall for background compared to polluted conditions. The observations of the GoAmazon2014/5 experiment illustrate how the hydrologic cycle, radiation balance, and carbon recycling may be affected by present-day as well as future economic development and pollution over the Amazonian tropical forest.

The intercontinental transport of aerosols from the Sahara desert plays a significant role in nutrient cycles in the Amazon rainforest, since it carries many types of minerals to these otherwise low-fertility lands. Iron is one of the micronutrients essential for plant growth, and its long-range transport might be an important source for the iron-limited Amazon rainforest. This study assesses the bioavailability of iron Fe(II) and Fe(III) in the particulate matter over the Amazon forest, which was transported from the Sahara desert (for the sake of our discussion, this term also includes the Sahel region). The sampling campaign was carried out above and below the forest canopy at the ATTO site (Amazon Tall Tower Observatory), a near-pristine area in the central Amazon Basin, from March to April 2015. Measurements reached peak concentrations for soluble Fe(III) (48 ng m−3), Fe(II) (16 ng m−3), Na (470 ng m−3), Ca (194 ng m−3), K (65 ng m−3), and Mg (89 ng m−3) during a time period of dust transport from the Sahara, as confirmed by ground-based and satellite remote sensing data and air mass backward trajectories. Dust sampled above the Amazon canopy included primary biological aerosols and other coarse particles up to 12 µm in diameter. Atmospheric transport of weathered Saharan dust, followed by surface deposition, resulted in substantial iron bioavailability across the rainforest canopy. The seasonal deposition of dust, rich in soluble iron, and other minerals is likely to assist both bacteria and fungi within the topsoil and on canopy surfaces, and especially benefit highly bioabsorbent species. In this scenario, Saharan dust can provide essential macronutrients and micronutrients to plant roots, and also directly to plant leaves. The influence of this input on the ecology of the forest canopy and topsoil is discussed, and we argue that this influence would likely be different from that of nutrients from the weathered Amazon bedrock, which otherwise provides the main source of soluble mineral nutrients.

Deriving absorption coefficients from Aethalometer attenuation data requires different corrections to compensate for artifacts related to filter-loading effects, scattering by filter fibers, and scattering by aerosol particles. In this study, two different correction schemes were applied to seven-wavelength Aethalometer data, using multi-angle absorption photometer (MAAP) data as a reference absorption measurement at 637 nm. The compensation algorithms were compared to five-wavelength offline absorption measurements obtained with a multi-wavelength absorbance analyzer (MWAA), which serves as a multiple-wavelength reference measurement. The online measurements took place in the Amazon rainforest, from the wet-to-dry transition season to the dry season (June–September 2014). The mean absorption coefficient (at 637 nm) during this period was 1.8 ± 2.1 Mm−1, with a maximum of 15.9 Mm−1. Under these conditions, the filter-loading compensation was negligible. One of the correction schemes was found to artificially increase the short-wavelength absorption coefficients. It was found that accounting for the aerosol optical properties in the scattering compensation significantly affects the absorption Ångström exponent (åABS) retrievals. Proper Aethalometer data compensation schemes are crucial to retrieve the correct åABS, which is commonly implemented in brown carbon contribution calculations. Additionally, we found that the wavelength dependence of uncompensated Aethalometer attenuation data significantly correlates with the åABS retrieved from offline MWAA measurements.

© 2016 American Chemical Society. Airborne biological particles, such as fungal spores and pollen, are ubiquitous in the Earth's atmosphere and may influence the atmospheric environment and climate, impacting air quality, cloud formation, and the Earth's radiation budget. The atmospheric transformations of airborne biological spores at elevated relative humidity remain poorly understood and their climatic role is uncertain. Using an environmental scanning electron microscope (ESEM), we observed rupturing of Amazonian fungal spores and subsequent release of submicrometer size fragments after exposure to high humidity. We find that fungal fragments contain elements of inorganic salts (e.g., Na and Cl). They are hygroscopic in nature with a growth factor up to 2.3 at 96% relative humidity, thus they may potentially influence cloud formation. Due to their hygroscopic growth, light scattering cross sections of the fragments are enhanced by up to a factor of 10. Furthermore, rupturing of fungal spores at high humidity may explain the bursting events of new particle formation in Amazonia.

The intercontinental transport of aerosols from the Sahara is likely to play a significant role in nutrient cycles in the Amazon rainforest, since it carries many types of minerals to these otherwise low-fertility lands. Iron is one of the micronutrients essential for plant growth, and the Amazon rainforest is iron-limited. The main aim of this study was to assess the input and potential impact of iron bioavailability from Saharan dust, namely, the soluble fraction Fe(II)/Fe(III). Seven other soluble elements that are also essential for plants were measured. Dust particles entrained in the air were collected and analyzed, but not dust deposited in rainfall as atmospheric washout. The sampling campaign was carried out at the ATTO site (Amazon Tall Tower Observatory), from March to April 2015, and samplers were placed both above and below the canopy. Mineral dust aerosol at ATTO showed peak concentrations for Fe(III) (47.6 ng m−3), Fe(II) (16.2 ng m−3), Na (470 ng m−3), Ca (194 ng m−3), K (64.7 ng m−3), and Mg (88.8 ng m−3) during the presence of dust transported from the Sahara, as determined by remote ground-based and satellite sensing data and backward trajectories. Atmospheric transport of weathered Saharan dust, followed by surface deposition, results in substantial iron bioavailability across the rainforest canopy. The seasonal deposition of dust rich in soluble iron and other minerals is likely to affect both bacteria and fungi within the topsoil and on canopy surfaces, and especially benefit highly bioabsorbent epiphytes, such as lichens. In this scenario, Saharan dust can provide essential macronutrients and micronutrients to plant roots, and also directly to plant leaves. The influence on the ecology of the forest canopy and topsoil would likely be different from that of nutrients from the weathered Amazon bedrock, which provides the main source of soluble mineral nutrients.

Large conurbations are a significant source of the anthropogenic pollution and demographic differences between cities that result in a different pollution burden. The metropolitan area of São Paulo (MASP, population 20 million) accounts for one fifth of the Brazilian vehicular fleet. A feature of MASP is the amount of ethanol used by the vehicular fleet, known to exacerbate air quality. The study describes the diurnal behaviour of the submicron aerosol and relies on total particle number concentration, particle number size distribution, light scattering and light absorption measurements. Modelled planetary boundary layer (PBL) depth and air mass movement data were used to aid the interpretation. During morning rush-hour, stagnant air and a shallow PBL height favour the accumulation of aerosol pollution. During clear-sky conditions, there was a wind shift towards the edge of the city indicating a heat island effect with implications on particulate pollution levels at the site. The median total particle number concentration for the submicron aerosol typically varied in the range 1.6 × 104–3.2 × 104 cm−3 frequently exceeding 4 × 104 cm−3 during the day. During weekdays, nucleation-mode particles are responsible for most of the particles by numbers. The highest concentrations of total particle number concentrations and black carbon (BC) were observed on Fridays. Median diurnal values for light absorption and light scattering (at 637 nm wavelength) varied in the range 12–33 Mm−1 and 21–64 Mm−1, respectively. The former one is equal to 1.8–5.0 μg m−3 of BC. The growth of the PBL, from the morning rush-hour until noon, is consistent with the diurnal cycle of BC mass concentrations. Weekday hourly median single-scattering albedo (ω0) varied in the range 0.59–0.76. Overall, this suggests a top of atmosphere (TOA) warming effect. However, considering the low surface reflectance of urban areas, for the given range of ω0, the TOA radiative forcing can be either positive or negative for the sources within the MASP. On the average, weekend ω0 values were 0.074 higher than during weekdays. During 11% of the days, new particle formation (NPF) events occurred. The analysed events growth rates ranged between 9 and 25 nm h−1. Sulphuric acid proxy concentrations calculated for the site were less than 5% of the concentration needed to explain the observed growth. Thus, other vapours are likely contributors to the observed growth.