Project A03:
Aerosol nucleation in the upper troposphere

Brief Summary

 The project investigates the physical and chemical processes of the formation of aerosol particles in the nanometer size range in the upper troposphere and lower stratosphere (UTLS). For that purpose, gaseous species that initiate the particle formation and contribute to the initial growth will be measured with high precision instruments onboard the German research aircraft HALO. The aerosol number concentration and other properties of the newly formed particles are measured as well. Our measurements allow an analysis of the detailed processes and efficiencies of aerosol formation in the UTLS region. A dedicated measurement campaign to investigate the new particle formation in the southern hemisphere is planned to take place in Argentina during austral summer in 2028. The measurements will be accompanied by detailed process modelling of aerosol composition and size. The models will range from process models, local to regional scale chemistry-weather models up to the global scale to quantify the relevance of particles formed in the extratropical UTLS for the climate system, e.g., the direct radiative impact of fresh and aged particles as well as their role in cloud formation and modification.

The upcoming results will be compared with the findings from the first phase of TPChange during which nitrogen containing organic molecules from isoprene, a compound naturally emitted by plants, have been identified as key ingredients for new particle formation in the tropical UTLS, especially over and downwind rainforest regions. Complex chemical mechanisms lead from the originally emitted isoprene to other species, which have a high potential of either nucleating fresh particles or condensing on existing aerosols, such that the competition between the energetically preferred condensation and new particle formation is key for the understanding of amount, size and composition of the aerosol in the UTLS.

Schematic of new aerosol particle formation in the UTLS from chemically transformed isoprene compounds and their potential role in the climate system. Figure from Curtius et al., Nature, 2024.

Project Poster

Evaluation Poster Phase I in 2025

Members

Publications

Bozem, H., P. Joppe, Y. Li, N. Emig, A. Afchine, A. Breuninger, J. Curtius, S. Hofmann, S. Ismayil, K. Kandler, D. Kunkel, A. Kutschka, H.-C. Lachnitt, A. Petzold, S. Richter, T. Röschenthaler, C. Rolf, L. Schneider, J. Schneider, A. Vogel, and P. Hoor (2025): The TropoPause Composition TOwed Sensor Shuttle (TPC-TOSS): A new airborne dual platform approach for atmospheric composition measurements at the tropopause. EGUsphere 2025, [Preprint], 1–34. doi: 10.5194/egusphere-2025-3175

Breuninger, A., P. Joppe, J. Wilsch, C. Schwenk, H. Bozem, N. Emig, L. Merkel, R. Rossberg, T. Keber, A. Kutschka, P. Waleska, S. Hofmann, S. Richter, F. Ungeheuer, K. Dörholt, T. Hoffmann, A. Miltenberger, J. Schneider, P. Hoor, and A. L. Vogel (2025): Organic aerosols mixing across the tropopause and its implication for anthropogenic pollution of the UTLS. EGUsphere 2025, [Preprint], 1–30. doi: 10.5194/egusphere-2025-3129.

Jeske, A. and H. Tost (2025): The historical climate trend resulted in changed vertical transport patterns in climate model simulations. Atmospheric Chemistry and Physics 25 (21), 14435–14448. doi: 10.5194/acp-25-14435-2025.

Richter, S., T. Keber, M. Heinritzi, L. Beck, L. Merkel, S. Kirchhoff, J. Schrod, P. Weber, and J. Curtius (2025): Characterization and operation of a multi-channel Condensation Particle Counter (mc-CPC) for aircraft-based measurements. EGUsphere 2025, [Preprint], 1–38. doi: 10.5194/egusphere-2025-4349.

Vella, R., M. Forrest, A. Pozzer, A. P. Tsimpidi, T. Hickler, J. Lelieveld, and H. Tost (2025a): Influence of land cover change on atmospheric organic gases, aerosols, and radiative effects. Atmospheric Chemistry and Physics 25 (1), 243–262. doi: 10.5194/acp-25-243-2025

Vella, R., S. Gromov, C. M. Nussbaumer, L. Stecher, M. Kohl, S. Ruhl, H. Tost, J. Lelieveld, and A. Pozzer (2025b): Changes in global atmospheric oxidant chemistry from land cover conversion. Atmospheric Chemistry and Physics 25 (17), 9885–9904. doi: 10.5194/acp-25-9885-2025.

Curtius, J., M. Heinritzi, L. J. Beck, M. L. Pöhlker, N. Tripathi, B. E. Krumm, P. Holzbeck, C. M. Nussbaumer, L. Hernández Pardo, T. Klimach, K. Barmpounis, S. T. Andersen, R. Bardakov, B. Bohn, M. A. Cecchini, J.-P. Chaboureau, T. Dauhut, D. Dienhart, R. Dörich, A. Edtbauer, A. Giez, A. Hartmann, B. A. Holanda, P. Joppe, K. Kaiser, T. Keber, H. Klebach, O. O. Krüger, A. Kürten, C. Mallaun, D. Marno, M. Martinez, C. Monteiro, C. Nelson, L. Ort, S. S. Raj, S. Richter, A. Ringsdorf, F. Rocha, M. Simon, S. Sreekumar, A. Tsokankunku, G. R. Unfer, I. D. Valenti, N. Wang, A. Zahn, M. Zauner-Wieczorek, R. I. Albrecht, M. O. Andreae, P. Artaxo, J. N. Crowley, H. Fischer, H. Harder, D. L. Herdies, L. A. T. Machado, C. Pöhlker, U. Pöschl, A. Possner, A. Pozzer, J. Schneider, J. Williams, and J. Lelieveld (2024): Isoprene nitrates drive new particle formation in Amazon’s upper troposphere. Nature 636, 124–130. doi: 10.1038/s41586-024-08192-4.

Bardakov, R., J. A. Thornton, A. M. L. Ekman, R. Krejci, M. L. Pöhlker, J. Curtius, J. Williams, J. Lelieveld, and I. Riipinen (2024): High Concentrations of Nanoparticles From Isoprene Nitrates Predicted in Convective Outflow Over the Amazon. Geophysical Research Letters 51 (23), e2024GL109919 2024GL109919, e2024GL109919. doi: https://doi.org/10.1029/2024GL109919.

Abdelkader, M., G. Stenchikov, A. Pozzer, H. Tost, and J. Lelieveld (2023): The effect of ash, water vapor, and heterogeneous chemistry on the evolution of a Pinatubo-size volcanic cloud. Atmospheric Chemistry and Physics 23 (1), 471–500. doi: https://doi.org/10.5194/acp-23-471-2023.

Zauner-Wieczorek, M., M. Heinritzi, M. Granzin, T. Keber, A. Kürten, K. Kaiser, J. Schneider, and J. Curtius (2022): Mass spectrometric measurements of ambient ions and estimation of gaseous sulfuric acid in the free troposphere and lowermost stratosphere during the CAFE-EU/BLUESKY campaign. Atmospheric Chemistry and Physics 22 (17), 11781–11794. doi: 10.5194/acp-22-11781-2022.