Isoprene nitrates drive new particle formation in Amazon’s upper troposphere - Archive ouverte HAL
Article Dans Une Revue Nature Année : 2024

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

Joachim Curtius
Martin Heinritzi
Lisa J Beck
Nidhi Tripathi
Bianca E Krumm
Philip Holzbeck
Clara M Nussbaumer
Simone T Andersen
Jean-Pierre Chaboureau
Thibaut Dauhut
Dirk Dienhart
Achim Edtbauer
Andreas Giez
Antonia Hartmann
Bruna A Holanda
Katharina Kaiser
Hannah Klebach
Ovid O Krüger
Daniel Marno
Monica Martinez
Carolina Monteiro
Carolina Nelson
Linda Ort
Sarah Richter
Akima Ringsdorf
Sreedev Sreekumar
Anywhere Tsokankunku
Nijing Wang
John N Crowley
Hartwig Harder
Ulrich Pöschl
Johannes Schneider

Résumé

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 .
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hal-04819823 , version 1 (04-12-2024)

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Joachim Curtius, Martin Heinritzi, Lisa J Beck, Mira L Pöhlker, Nidhi Tripathi, et al.. Isoprene nitrates drive new particle formation in Amazon’s upper troposphere. Nature, 2024, 636 (8041), pp.124-130. ⟨10.1038/s41586-024-08192-4⟩. ⟨hal-04819823⟩
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