New Publication: Variability of black and brown carbon concentrations

We are currently in the middle of the dry season in the central Amazon basin, where ATTO is located. This time of year is always characterized by lots of biomass burnings, both natural and anthropogenic. Fires produce aerosols, such as black and brown carbon. But the situation isn’t the same every year.

First-author Jorge Saturno just published the study in Atmospheric Chemistry and Physics (ACP) Issue 18. It is available Open Access and thus freely available for everyone.

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Smoke from biomass burning rises into the atmosphere over the central Amazon basin. © NASA

Soot and other aerosols from biomass burning can influence regional and global weather and climate. Lixia Liu and her colleagues studied how this affects the Amazon Basin during the dry season. While there are many different interactions between biomass burning aerosols and climate, they found that they overall lead to fewer and weaker rain events in the Amazon rainforest.

When forests burn those fires produce a lot of smoke. And that smoke usually contains soot, also called “black carbon”. Black carbon particles are aerosols that absorb radiation and as such can warm the Earth’s atmosphere and climate. But we still have much to learn about aerosols, their properties, and distribution in the atmosphere. One of those things is the question of how black carbon emitted from biomass burning in Africa (i.e. forests, grasslands, savannas etc.) is transported across the Atlantic and into the Amazon basin, and what role it plays there. Bruna Holanda and her co-authors tackled this in their new study published in ACP.

New Publication: Aerosol composition and cloud dynamics

The properties and dynamics of clouds are strongly dependent on the types and amounts of aerosol particles in the atmosphere. They act as so-called cloud condensation nuclei as they initiate the formation of cloud droplets. Therefore, it is crucial to gain a sound understanding of the emission patterns, properties, and seasonal variability of aerosols in relation to the cloud life cycles. In order to achieve this goal, our aerosol group was able to record such data at ATTO. Over the course of a full year, they continuously measured aerosols and their properties in the atmosphere at the 80 m tower. Thus, they created the first such long-term record in the Amazon.

The results of the study were published in two parts; the first was released in 2016 and focused on the parameterization of the aerosol properties. This provides the scientific community with input for models to better predict atmospheric cycling and future climate. Because clouds are such a vital and highly complex component of the climate system, it is important for models to get them “right” in order to make reliable predictions.

In this newly published second part of the study, the authors focused on defining the most distinctive states of aerosol composition and associated cloud formation conditions in the ATTO region. They distinguished between four separate regimes that alternate throughout the year. For example, they discovered that the atmosphere is practically pristine during certain episodes in the wet season (from March to May), with no detectable influence of pollution. However, throughout the rest of the year, “foreign” aerosols arrive at the site in varying amounts. They include natural aerosol particles such as Saharan dust, but also pollutants such as smoke from biomass burning (wildfires and much more often deforestation fires) within the Amazon or even in Africa.

Part 1 and Part 2 of this study were published by first author Mira Pöhlker in Atmospheric Chemistry and Physics (ACP) Issues 16 and 18. They are available Open Access and thus freely available for everyone.

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The Amazon rain forest plays a major role in global hydrological cycling. Biogenic aerosols, such as pollen, fungi, and spores likely influence the formation of clouds and precipitation. However, there are many different types of bioaerosols. The particles vary considerably in size, morphology, mixing state, as well as behavior like hygroscopicity (how much particles attract water) and metabolic activity. Therefore, it is likely that not only the amount of bioaerosols affects the hydrological cycle, but also the types of aerosols present.

SEM images of different types of bioaerosols. @Sachin Patade / Uni Lund

Bioaerosols may act as cloud condensation nuclei and ice nuclei, thereby influencing the formation of clouds and precipitation. But so far there is less knowledge about the ice nucleation activity of each bioaerosol group and atmospheric models hitherto have not differentiated between them. Patade et al. created a new empirical parameterization for five groups of bioaerosols, based on analysis of the characteristics of bioaerosols at ATTO: fungal spores, bacteria, pollen, plant/animal/viral detritus, and algae. This makes it possible for any cloud model to access the role of an individual group of bioaerosols in altering cloud properties and precipitation formation.

The majority of global precipitation is formed through the pathway of ice nucleation, but we’re facing large knowledge gaps that include the distribution, seasonal variations and sources of ice-nucleating particles. To fill some of those knowledge gaps, Jann Schrod and his co-authors produced a record of long-term measurements of INPs. They collected data for nearly two years at four different locations. One of those sites was ATTO.

GRAEGOR detector unit for measuring trace gases like nitrogen in the laboratory container. © Robbie Ramsay / University of Edinburgh

Ramsay et al. measured inorganic trace gases such as ammonia and nitric acid and aerosols in the dry season at ATTO. They are to serve as baseline values for their concentration and fluxes in the atmosphere and are a first step in deciphering exchange processes of inorganic trace gases between the Amazon rainforest and the atmosphere.

Smoke from biomass burning rises into the atmosphere over the central Amazon basin. © NASA

Soot and other aerosols from biomass burning can influence regional and global weather and climate. Lixia Liu and her colleagues studied how this affects the Amazon Basin during the dry season. While there are many different interactions between biomass burning aerosols and climate, they found that they overall lead to fewer and weaker rain events in the Amazon rainforest.

Graphical Abstract

In a new study, Dr. Haijie Tong and co-authors studied a subset of PM2.5, the so-called highly oxygenated molecules (HOMs) and its relationship with radical yield and aerosol oxidative potential. They analyzed fine particulate matter in the air in multiple locations. This including the highly polluted megacity Bejing and in the pristine rainforest at ATTO. They wanted to get insights into the chemical characteristic and evolutions of these HOM particles. In particular, they wanted to find out more about the potential of HOMs to form free radicals. These are highly reactive species with unpaired electrons.

Wu et al. collected and analyzed aerosols in two locations: the city of Manaus, a large urban area in Brazil, and the ATTO site in the heart of the forest. The aerosol compositions varied largly. At ATTO most aerosols were emitted by the forest itself, while in Manaus, anthropogenic aerosols were very common. The results were published in ACP.

Moran-Zuloaga et al. analyzed the coarse fraction of aerosols every 5 minutes for over 3 years at ATTO. They found that the composition remains fairly constant throughout the year, except for a short period in the wet season when Saharan dust occurs regularly. They published their results in ACP.

New publication: African volcanic emissions reach Amazon

By the long-range transport of particles, such as sulfate, across the Atlantic to the Amazon rainforest and to better understand atmospheric cycling. A good opportunity for that arose in 2014. Some of the most active volcanoes worldwide, the Nyamuragira and Mount Nyiragongo volcanoes in Congo in Central Africa, erupted violently.

During this eruption, they emitted a lot of sulfur dioxide (SO2) into the atmosphere. This gas that is later converted to sulfate particles by oxidation. Usually, these particles are diluted in the atmosphere as they mix with other particles. It thus becomes difficult to distinguish them far away from their source. However, the emissions of 2014 were so strong that the sulfate particles originating from the volcanic gas were observed over the Amazon rainforest by ground-based instruments at our ATTO site (specifically at the 80 m tall triangular mast) and by aircraft measurements (during the ACRIDICON-CHUVA campaign). This observation is now being used by ATTO scientists as a case study to understand how gas and particle emissions from Africa are transported over the Atlantic Ocean and reach the Amazon Basin.

For scale, the volcanoes in Congo are almost 10,000 km away from ATTO, and it took the particles around 2 weeks to bridge that distance!

The full study was just published in Atmospheric Chemistry and Physics (ACP) Issue 18 by first author Jorge Saturno. It is available Open Access and thus freely available for everyone.

Similar articles

GRAEGOR detector unit for measuring trace gases like nitrogen in the laboratory container. © Robbie Ramsay / University of Edinburgh

Ramsay et al. measured inorganic trace gases such as ammonia and nitric acid and aerosols in the dry season at ATTO. They are to serve as baseline values for their concentration and fluxes in the atmosphere and are a first step in deciphering exchange processes of inorganic trace gases between the Amazon rainforest and the atmosphere.

Smoke from biomass burning rises into the atmosphere over the central Amazon basin. © NASA

Soot and other aerosols from biomass burning can influence regional and global weather and climate. Lixia Liu and her colleagues studied how this affects the Amazon Basin during the dry season. While there are many different interactions between biomass burning aerosols and climate, they found that they overall lead to fewer and weaker rain events in the Amazon rainforest.

When forests burn those fires produce a lot of smoke. And that smoke usually contains soot, also called “black carbon”. Black carbon particles are aerosols that absorb radiation and as such can warm the Earth’s atmosphere and climate. But we still have much to learn about aerosols, their properties, and distribution in the atmosphere. One of those things is the question of how black carbon emitted from biomass burning in Africa (i.e. forests, grasslands, savannas etc.) is transported across the Atlantic and into the Amazon basin, and what role it plays there. Bruna Holanda and her co-authors tackled this in their new study published in ACP.

Saturno et al. analyzed the concentration of black and brown carbon in the atmosphere above the Amazon. They found that the dry season is characterized by lots of biomass burnings, which produce a lot of black and brown carbon. But they also sound significant interannual variations. The results were published in ACP.

New publication on aerosols in the Amazon

Scientists from our Aerosol group published a new “Long-term study on coarse mode aerosols in the Amazon rainforest with the frequent intrusion of Saharan dust plumes”.

They analyzed the coarse fraction of aerosols (those that are at least 1 micrometer in diameter) every 5 minutes for over 3 years and were surprised to find that over this period the size and abundance of these “large” aerosol particles remained fairly constant. In contrast, the smaller aerosols are heavily influenced by the seasonal occurrence of smoke from fires. This coarse fraction, however, is mainly comprised of aerosols derived from the rainforest itself (such as pollen). That pattern only changes during the wet season (December through April), when Saharan dust, sea salt particles from the Atlantic and smoke from fires in Africa episodically make their way to the Amazon. Especially in February and March, pulses of African aerosols become so frequent they are the norm rather than the exception. Our scientists then used these data to estimate how much dust is deposited in the ATTO region each year: 5-10 kg per hectare, or 0.5-1 g per square meter.

You can read the full study by lead author Daniel Moran-Zuloaga in Atmospheric Chemistry and Physics Issue 18. It is published Open Access and thus freely available online. The data set is also available for further analysis (see publication for details)!

Similar articles

The Amazon rain forest plays a major role in global hydrological cycling. Biogenic aerosols, such as pollen, fungi, and spores likely influence the formation of clouds and precipitation. However, there are many different types of bioaerosols. The particles vary considerably in size, morphology, mixing state, as well as behavior like hygroscopicity (how much particles attract water) and metabolic activity. Therefore, it is likely that not only the amount of bioaerosols affects the hydrological cycle, but also the types of aerosols present.

GRAEGOR detector unit for measuring trace gases like nitrogen in the laboratory container. © Robbie Ramsay / University of Edinburgh

Ramsay et al. measured inorganic trace gases such as ammonia and nitric acid and aerosols in the dry season at ATTO. They are to serve as baseline values for their concentration and fluxes in the atmosphere and are a first step in deciphering exchange processes of inorganic trace gases between the Amazon rainforest and the atmosphere.

Smoke from biomass burning rises into the atmosphere over the central Amazon basin. © NASA

Soot and other aerosols from biomass burning can influence regional and global weather and climate. Lixia Liu and her colleagues studied how this affects the Amazon Basin during the dry season. While there are many different interactions between biomass burning aerosols and climate, they found that they overall lead to fewer and weaker rain events in the Amazon rainforest.

When forests burn those fires produce a lot of smoke. And that smoke usually contains soot, also called “black carbon”. Black carbon particles are aerosols that absorb radiation and as such can warm the Earth’s atmosphere and climate. But we still have much to learn about aerosols, their properties, and distribution in the atmosphere. One of those things is the question of how black carbon emitted from biomass burning in Africa (i.e. forests, grasslands, savannas etc.) is transported across the Atlantic and into the Amazon basin, and what role it plays there. Bruna Holanda and her co-authors tackled this in their new study published in ACP.

Graphical Abstract

In a new study, Dr. Haijie Tong and co-authors studied a subset of PM2.5, the so-called highly oxygenated molecules (HOMs) and its relationship with radical yield and aerosol oxidative potential. They analyzed fine particulate matter in the air in multiple locations. This including the highly polluted megacity Bejing and in the pristine rainforest at ATTO. They wanted to get insights into the chemical characteristic and evolutions of these HOM particles. In particular, they wanted to find out more about the potential of HOMs to form free radicals. These are highly reactive species with unpaired electrons.

Wu et al. collected and analyzed aerosols in two locations: the city of Manaus, a large urban area in Brazil, and the ATTO site in the heart of the forest. The aerosol compositions varied largly. At ATTO most aerosols were emitted by the forest itself, while in Manaus, anthropogenic aerosols were very common. The results were published in ACP.

Saturno et al. analyzed the concentration of black and brown carbon in the atmosphere above the Amazon. They found that the dry season is characterized by lots of biomass burnings, which produce a lot of black and brown carbon. But they also sound significant interannual variations. The results were published in ACP.

Mira Pöhlker and her team continuously measured aerosols and their properties in the atmosphere at the 80 m tower at ATTO, thereby created the first such long-term record in the Amazon. They analyzed the data in two subsequent paper. The second was now published in ACP.

Saturno et al. used the eruption of two volcanoes in Congo to trace the transport of sulfate particles from Central Africa to the Amazon basin. They are using this as a case study to understand how gas and particle emissions from Africa are transported over the Atlantic Ocean. The results are published in ACP.