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.

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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)!

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