Newswise — A recent study conducted by the University of Helsinki has revealed that oxidized organic molecules derived from the Amazon rainforest play a crucial role in the generation of aerosol particles in the tropical free troposphere. These aerosol particles have a significant impact on the global climate as they act as a substantial source of cloud condensation nuclei. However, the origin of these particles has been a mystery until now.
The findings, published in the National Science Review, present evidence of the existence of low-volatile organic compounds in the free tropospheric air above the Amazon. This discovery provides valuable insights into the mechanisms behind aerosol particle formation in this particular region.
Professor Federico Bianchi, the corresponding author of the paper from the University of Helsinki, emphasizes the importance of understanding oxidized organic molecules for comprehending aerosol formation in pristine environments resembling the pre-industrial era, such as the tropical free troposphere. However, studying these compounds at the molecular level is exceptionally challenging due to their minimal concentrations, particularly under high-altitude conditions.
Measurements done at the top of the Chacaltaya mountain
The researchers made a significant discovery regarding the presence of oxidized organic molecules in both the gas phase and aerosol particles in the tropical free troposphere. These molecules, primarily consisting of 4-5 carbon atoms, were found to be linked to isoprene emissions from the Amazon rainforest, even though the rainforest is located hundreds of kilometers away. These low-volatile organic compounds have the potential to nucleate or condense on newly formed nanoparticles, thus playing a crucial role in the process of aerosol formation in the tropical free troposphere.
Dr. Qiaozhi Zha, the lead author of the paper, highlights the influence of isoprene-derived oxidized organic molecules on the formation of aerosol particles on a continental scale in the tropical free troposphere. This discovery has significant implications for aerosol particles in the boundary layer, cloud formation, and ultimately global climate. The findings also provide important constraints for modeling tropical aerosols in future studies aimed at understanding their impact on climate.
To conduct their research, atmospheric scientists are carrying out field measurements at the Chacaltaya GAW station, which is part of the Global Atmosphere Watch network. This station, situated near La Paz in Bolivia, is located on the outskirts of the Amazon rainforest and stands at an elevation of 5240 meters above sea level, making it the highest atmospheric laboratory in the world.
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