2024-12-04 ゲーテ大学
＜関連情報＞
- https://aktuelles.uni-frankfurt.de/english/the-amazon-rainforest-as-a-cloud-machine-how-thunderstorms-and-plant-transpiration-produce-condensation-nuclei/
- https://www.nature.com/articles/s41586-024-08192-4
- https://www.nature.com/articles/s41586-024-08196-0
アマゾンの対流圏上部でイソプレン硝酸塩が新たな粒子形成を促進 Isoprene nitrates drive new particle formation in Amazon’s upper troposphere
Joachim Curtius,Martin Heinritzi,Lisa J. Beck,Mira L. Pöhlker,Nidhi Tripathi,Bianca E. Krumm,Philip Holzbeck,Clara M. Nussbaumer,Lianet Hernández Pardo,Thomas Klimach,Konstantinos Barmpounis,Simone T. Andersen,Roman Bardakov,Birger Bohn,Micael A. Cecchini,Jean-Pierre Chaboureau,Thibaut Dauhut,Dirk Dienhart,Raphael Dörich,Achim Edtbauer,Andreas Giez,Antonia Hartmann,Bruna A. Holanda,Philipp Joppe,… Jos Lelieveld
Nature Published:04 December 2024
DOI:https://doi.org/10.1038/s41586-024-08192-4
Abstract
New particle formation (NPF) in the tropical upper troposphere is a globally important source of atmospheric aerosols1,2,3,4. It is known to occur over the Amazon basin, but the nucleation mechanism and chemical precursors have yet to be identified2. 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 climate1,4,5,6,7,8.
対流圏上層条件下におけるイソプレンからの新たな粒子形成 New particle formation from isoprene under upper-tropospheric conditions
Jiali Shen,Douglas M. Russell,Jenna DeVivo,Felix Kunkler,Rima Baalbaki,Bernhard Mentler,Wiebke Scholz,Wenjuan Yu,Lucía Caudillo-Plath,Eva Sommer,Emelda Ahongshangbam,Dina Alfaouri,João Almeida,Antonio Amorim,Lisa J. Beck,Hannah Beckmann,Moritz Berntheusel,Nirvan Bhattacharyya,Manjula R. Canagaratna,Anouck Chassaing,Romulo Cruz-Simbron,Lubna Dada,Jonathan Duplissy,Hamish Gordon,… Xu-Cheng He
Nature Published:04 December 2024
DOI:https://doi.org/10.1038/s41586-024-08196-0
Abstract
Aircraft observations have revealed ubiquitous new particle formation in the tropical upper troposphere over the Amazon1,2 and the Atlantic and Pacific oceans3,4. Although the vapours involved remain unknown, recent satellite observations have revealed surprisingly high night-time isoprene mixing ratios of up to 1 part per billion by volume (ppbv) in the tropical upper troposphere5. Here, in experiments performed with the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we report new particle formation initiated by the reaction of hydroxyl radicals with isoprene at upper-tropospheric temperatures of −30 °C and −50 °C. We find that isoprene-oxygenated organic molecules (IP-OOM) nucleate at concentrations found in the upper troposphere, without requiring any more vapours. Moreover, the nucleation rates are enhanced 100-fold by extremely low concentrations of sulfuric acid or iodine oxoacids above 105 cm−3, reaching rates around 30 cm−3 s−1 at acid concentrations of 106 cm−3. Our measurements show that nucleation involves sequential addition of IP-OOM, together with zero or one acid molecule in the embryonic molecular clusters. IP-OOM also drive rapid particle growth at 3–60 nm h−1. We find that rapid nucleation and growth rates persist in the presence of NOx at upper-tropospheric concentrations from lightning. Our laboratory measurements show that isoprene emitted by rainforests may drive rapid new particle formation in extensive regions of the tropical upper troposphere1,2, resulting in tens of thousands of particles per cubic centimetre.
