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Isoprene nitrates drive new particle formation in Amazon’s upper troposphere

2024; Nature Portfolio; Volume: 636; Issue: 8041 Linguagem: Inglês

10.1038/s41586-024-08192-4

1476-4687

Joachim Curtius, Martin Heinritzi, Lisa Beck, Mira L. Pöhlker, Nidhi Tripathi, Bianca Krumm, Philip Holzbeck, Clara M. Nussbaumer, Lianet Hernández Pardo, Thomas Klimach, K. Barmpounis, Simone T. Andersen, Roman Bardakov, Birger Bohn, Micael A. Cecchini, Jean‐Pierre Chaboureau, Thibaut Dauhut, Dirk Dienhart, Raphael Dörich, Achim Edtbauer, Andreas Giez, Arndt Hartmann, Bruna A. Holanda, Philipp Joppe, Katharina Kaiser, Timo Keber, Hannah Klebach, Ovid O. Krüger, Andreas Kürten, Christian Mallaun, Daniel Marno, Mónica Martínez, Carolina Monteiro, Carolina Nelson, Linda Ort, Subha S. Raj, Sarah Richter, Akima Ringsdorf, Fábio Lopes Rocha, Mario Simon, Sreedev Sreekumar, Anywhere Tsokankunku, Gabriela Rosalino Unfer, Isabella D. Valenti, Nijing Wang, Andreas Zahn, Marcel Zauner-Wieczorek, Rachel I. Albrecht, Meinrat O. Andreae, Paulo Artaxo, John N. Crowley, Horst Fischer, Hartwig Harder, Dirceu Luís Herdies, Luiz A. T. Machado, Christopher Pöhlker, Ulrich Pöschl, Anna Possner, Andrea Pozzer, Johannes Schneider, Jonathan Williams, Jos Lelieveld,

Atmospheric Ozone and Climate

Abstract New particle formation (NPF) in the tropical upper troposphere is a globally important source of atmospheric aerosols 1–4 . It is known to occur over the Amazon basin, but the nucleation mechanism and chemical precursors have yet to be identified 2 . Here we present comprehensive in situ aircraft measurements showing that extremely low-volatile oxidation products of isoprene, particularly certain organonitrates, drive NPF in the Amazonian upper troposphere. The organonitrates originate from OH-initiated oxidation of isoprene from forest emissions in the presence of nitrogen oxides from lightning. Nucleation bursts start about 2 h after sunrise in the outflow of nocturnal deep convection, producing high aerosol concentrations of more than 50,000 particles cm − 3 . We report measurements of characteristic diurnal cycles of precursor gases and particles. Our observations show that the interplay between biogenic isoprene, deep tropical convection with associated lightning, oxidation photochemistry and the low ambient temperature uniquely promotes NPF. The particles grow over time, undergo long-range transport and descend through subsidence to the lower troposphere, in which they can serve as cloud condensation nuclei (CCN) that influence the Earth’s hydrological cycle, radiation budget and climate 1,4–8 .