Project A01:
Impact of aircraft emissions and convection on the composition of the UTLS

Brief Summary

The composition and the radiative balance of the tropopause region can be influenced by natural and anthropogenic aerosols. Also, aircraft act as a direct source of aerosols into this region. In cold and humid conditions, engine-emitted aerosols can promote the formation of contrails and perturb natural cirrus clouds. Studies suggest that the climate impact from contrails could be comparable with that from all aircraft CO2 emissions since beginning of commercial air traffic. To enhance our understanding of contrail formation and climate impact, and assess the potential of mitigation strategies, targeted in-flight measurements are required.

Aerosol precursors can be transported into the tropopause region by convective systems. New particle formation in the outflow of convective systems has been found to depend on the concentrations of aerosol precursor species. In-situ measurements of gas phase sulphur dioxide and nitric acid can help to investigate the dependency of new particle formation on these precursor gases, in particular in the extratropical UTLS.

During the HALO aircraft campaigns AEROCLOUD-FIRE in 2027 and CONTANGO-FIRE in 2028, the project A01 will measure sulphur dioxide and nitric acid, along with microphysical properties of contrails and cirrus clouds over America and Europe.

Within TPChange Phase II, A01 aims to partially answer questions related to RQ-A1, RQ-A2, RQ-A3, and RQ-C1. More specifically, the project will utilize data from the two HALO missions to address the following key questions: How do aircraft emissions influence the chemical composition, microphysical processes and the radiative balance of the tropopause region? And, how does aerosol and ice nucleation within extratropical convective outflows depend on the concentrations of precursor gases SO2 and HNO3? The data will be used to evaluate a contrail model (CoCiP), and climate models (EMAC, ICON), closely collaborating with 8 other projects in TPChange research areas A, B, C, and Z.

Photo of a contrail forming behind an aircraft (A321neo) with modern lean-burn LEAP-1A engines.

Project Poster

Evaluation Poster Phase I in 2025

Members

Publications

De La Torre Castro, E., C. G. Beer, T. Jurkat-Witschas, D. Sauer, M. Righi, J. Hendricks, and C. Voigt (2025): A combined observational and modelling approach to evaluate aerosol-cirrus interactions at high and mid-latitudes. EGUsphere 2025, 1–30. doi: 10.5194/egusphere-2025-3913

Ehrlich, A., S. Crewell, A. Herber, M. Klingebiel, C. Lüpkes, M. Mech, S. Becker, S. Borrmann, H. Bozem, M. Buschmann, H.-C. Clemen, E. De La Torre Castro, H. Dorff, R. Dupuy, O. Eppers, F. Ewald, G. George, A. Giez, S. Grawe, C. Gourbeyre, J. Hartmann, E. Jäkel, P. Joppe, O. Jourdan, Z. Jurányi, B. Kirbus, J. Lucke, A. E. Luebke, M. Maahn, N. Maherndl, C. Mallaun, J. Mayer, S. Mertes, G. Mioche, M. Moser, H. Müller, V. Pörtge, N. Risse, G. Roberts, S. Rosenburg, J. Röttenbacher, M. Schäfer, J. Schaefer, A. Schäfler, I. Schirmacher, J. Schneider, S. Schnitt, F. Stratmann, C. Tatzelt, C. Voigt, A. Walbröl, A. Weber, B. Wetzel, M. Wirth, and M. Wendisch (2025): A comprehensive in situ and remote sensing data set collected during the HALO–(AC)3 aircraft campaign. Earth System Science Data 17 (3), 1295–1328. doi: 10.5194/essd-17-1295-2025.

Jurkat-Witschas, T., C. Voigt, S. Groß, S. Kaufmann, D. Sauer, E. D. la Torre Castro, M. Krämer, A. Schäfler, A. Afchine, R. Attinger, I. B. Garcia, C. G. Beer, L. Bugliaro, H.-C. Clemen, G. Dekoutsidis, A. Ehrlich, S. Grawe, V. Hahn, J. Hendricks, E. Järvinen, K. Thomas, K. Krüger, K. Ovid, J. Lucke, A. E. Luebke, A. Marsing, B. Mayer, J. Mayer, S. Mertes, M. Moser, H. Müller, V. Nenakhov, M. Pöhlker, U. Pöschl, V. Pörtge, M. Rautenhaus,
M. Righi, J. Röttenbacher, M. Rubin-Zuzic, J. Schaefer, M. Schnaiter, J. Schneider, U. Schumann, N. Spelten, F. Stratmann, L. Tomsche, S. Wagner, Z. Wang, A. Weber, M. Wendisch, H. Wernli, B. Wetzel, M. Wirth, A. Zahn, H. Ziereis, and M. Zöger (2025): CIRRUS-HL: Picturing high- and mid-latitude summer cirrus and contrail cirrus above Europe with airborne measurements aboard the research aircraft HALO. Bulletin of the American Meteorological Society, BAMS-D-23–0270.1. doi: 10.1175/BAMS-D-23-0270.1

Moser, M., C. Voigt, O. Eppers, J. Lucke, E. De La Torre Castro, J. Mayer, R. Dupuy, G. Mioche, O. Jourdan, H.-C. Clemen, J. Schneider, P. Joppe, S. Mertes, B. Wetzel, S. Borrmann, M. Klingebiel, M. Mech, C. Lüpkes, S. Crewell, A. Ehrlich, A. Herber, and M. Wendisch (2025a): The Arctic Low-Level Mixed-Phase Haze Regime and its Microphysical Differences to Mixed-Phase Clouds. EGUsphere 2025, [Preprint], 1–33. doi: 10.5194/egusphere-2025-3876.

Voigt, C., R. Märkl, and D. S. et al. (2025): Substantial aircraft contrail formation at low soot emission levels. Research Square, [Preprint]. doi: https://doi.org/10.21203/rs.3.rs-6559440/v1. Submitted to Nature

Voigt, C. (2025): Solving aviation’s climate-action conundrum: A decision-making tool for the aviation sector helps to assess the likelihood of a net positive outcome from climate actions that can have competing effects on warming. Nature, doi: https://doi.org/10.1038/d41586-025-02129-1

Li, X.-Y., H. Wang, M. W. Christensen, J. Chen, S. Tang, S. Kirschler, E. Crosbie, L. D. Ziemba, D. Painemal, A. F. Corral, K. A. McCauley, S. Dmitrovic, A. Sorooshian, M. Fenn, J. S. Schlosser, S. Stamnes, J. W. Hair, B. Cairns, R. Moore, R. A. Ferrare, M. A. Shook, Y. Choi, G. S. Diskin, J. DiGangi, J. B. Nowak, C. Robinson, T. J. Shingler, K. Lee Thornhill, and C. Voigt (2024): Process Modeling of Aerosol-Cloud Interaction in Summertime Precipitating Shallow Cumulus Over the Western North Atlantic. Journal of Geophysical Research: Atmospheres 129 (7), e2023JD039489. doi: https://doi.org/10.1029/2023JD039489.

Maherndl, N., M. Moser, J. Lucke, M. Mech, N. Risse, I. Schirmacher, and M. Maahn (2024): Quantifying riming from airborne data during the HALO-(AC)3 campaign. Atmospheric Measurement Techniques 17 (5), 1475–1495. doi: 10.5194/amt-17-1475-2024.

De La Torre Castro, E., T. Jurkat-Witschas, A. Afchine, V. Grewe, V. Hahn, S. Kirschler, M. Krämer, J. Lucke, N. Spelten, H. Wernli, M. Zöger, and C. Voigt (2023): Differences in microphysical properties of cirrus at high and mid-latitudes. Atmospheric Chemistry and Physics 23 (20), 13167–13189. doi: 10.5194/acp-23-13167-2023.

Groß, S., T. Jurkat-Witschas, Q. Li, M. Wirth, B. Urbanek, M. Krämer, R. Weigel, and C. Voigt (2023): Investigating an indirect aviation effect on mid-latitude cirrus clouds – linking lidar-derived optical properties to in situ measurements. Atmospheric Chemistry and Physics 23 (14), 8369–8381. doi: https://doi.org/10.5194/acp-23-8369-2023.

Kirschler, S., C. Voigt, B. E. Anderson, G. Chen, E. C. Crosbie, R. A. Ferrare, V. Hahn, J. W. Hair, S. Kaufmann, R. H. Moore, D. Painemal, C. E. Robinson, K. J. Sanchez, A. J. Scarino, T. J. Shingler, M. A. Shook, K. L. Thornhill, E. L. Winstead, L. D. Ziemba, and A. Sorooshian (2023): Overview and statistical analysis of boundary layer clouds and precipitation over the western North Atlantic Ocean. Atmospheric Chemistry and Physics 23 (18), 10731–10750. doi: 10.5194/acp-23-10731-20.

Li, X.-Y., H. Wang, J. Chen, S. Endo, S. Kirschler, C. Voigt, E. Crosbie, L. D. Ziemba, D. Painemal, B. Cairns, J. W. Hair, A. F. Corral, C. Robinson, H. Dadashazar, A. Sorooshian, G. Chen, R. A. Ferrare, M. M. Kleb, H. Liu, R. Moore, A. J. Scarino, M. A. Shook, T. J. Shingler, K. L. Thornhill, F. Tornow, H. Xiao, and X. Zeng (2023): Large-Eddy Simulations of Marine Boundary Layer Clouds Associated with Cold-Air Outbreaks during the ACTIVATE Campaign. Part II: Aerosol–Meteorology–Cloud Interaction. Journal of the Atmospheric Sciences 80 (4), 1025–1045. doi: https://doi.org/10.1175/JAS-D-21-0324.1.

Moser, M., C. Voigt, T. Jurkat-Witschas, V. Hahn, G. Mioche, O. Jourdan, R. Dupuy, C. Gourbeyre, A. Schwarzenboeck, J. Lucke, Y. Boose, M. Mech, S. Borrmann, A. Ehrlich, A. Herber, C. Lüpkes, and M. Wendisch (2023): Microphysical and thermodynamic phase analyses of Arctic low-level clouds measured above the sea ice and the open ocean in spring and summer. Atmospheric Chemistry and Physics 23 (13), 7257–7280. doi: 10.5194/acp-23-7257-202.

Wang, Z., L. Bugliaro, T. Jurkat-Witschas, R. Heller, U. Burkhardt, H. Ziereis, G. Dekoutsidis, M. Wirth, S. Groß, S. Kirschler, S. Kaufmann, and C. Voigt (2023): Observations of microphysical properties and radiative effects of a contrail cirrus outbreak over the North Atlantic. Atmospheric Chemistry and Physics 23 (3), 1941–1961. doi: https://doi.org/10.5194/acp-23-1941-2023.

Dischl, R., S. Kaufmann, and C. Voigt (2022): Regional and Seasonal Dependence of the Potential Contrail Cover and the Potential Contrail Cirrus Cover over Europe. Aerospace 9 (9),  doi: https://doi.org/10.3390/aerospace9090485.

Li, X.-Y., H. Wang, J. Chen, S. Endo, G. George, B. Cairns, S. Chellappan, X. Zeng, S. Kirschler, C. Voigt, A. Sorooshian, E. Crosbie, G. Chen, R. A. Ferrare, W. I. Gustafson, J. W. Hair, M. M. Kleb, H. Liu, R. Moore, D. Painemal, C. Robinson, A. J. Scarino, M. Shook, T. J. Shingler, K. L. Thornhill, F. Tornow, H. Xiao, L. D. Ziemba, and P. Zuidema (2022): Large-Eddy Simulations of Marine Boundary Layer Clouds Associated with Cold-Air Outbreaks during the ACTIVATE Campaign. Part I: Case Setup and Sensitivities to Large-Scale Forcings. Journal of the Atmospheric Sciences 79 (1), 73–100. doi: https://doi.org/10.1175/JAS-D-21-0123.1.

Reifenberg, S. F., A. Martin, M. Kohl, S. Bacer, Z. Hamryszczak, I. Tadic, L. Röder, D. J. Crowley, H. Fischer, K. Kaiser, J. Schneider, R. Dörich, J. N. Crowley, L. Tomsche, A. Marsing, C. Voigt, A. Zahn, C. Pöhlker, B. A. Holanda, O. Krüger, U. Pöschl, M. Pöhlker, P. Jöckel, M. Dorf, U. Schumann, J. Williams, B. Bohn, J. Curtius, H. Harder, H. Schlager, J. Lelieveld, and A. Pozzer (2022): Numerical simulation of the impact of COVID-19 lockdown on tropospheric composition and aerosol radiative forcing in Europe. Atmospheric Chemistry and Physics 22 (16), 10901–10917. doi: https://doi.org/10.5194/acp-22-10901-2022.

Tomsche, L., A. Marsing, T. Jurkat-Witschas, J. Lucke, S. Kaufmann, K. Kaiser, J. Schneider, M. Scheibe, H. Schlager, L. Röder, H. Fischer, F. Obersteiner, A. Zahn, M. Zöger, J. Lelieveld, and C. Voigt (2022): Enhanced sulfur in the upper troposphere and lower stratosphere in spring 2020. Atmospheric Chemistry and Physics 22 (22), 15135–15151. doi: https://doi.org/10.5194/acp-22-15135-2022.

Tornow, F., A. S. Ackerman, A. M. Fridlind, B. Cairns, E. C. Crosbie, S. Kirschler, R. H. Moore, D. Painemal, C. E. Robinson, C. Seethala, M. A. Shook, C. Voigt, E. L. Winstead, L. D. Ziemba, P. Zuidema, and A. Sorooshian (2022): Dilution of Boundary Layer Cloud Condensation Nucleus Concentrations by Free Tropospheric Entrainment During Marine Cold Air Outbreaks. Geophysical Research Letters 49 (11), e2022GL098444. doi: https://doi.org/10.1029/2022GL098444.

Voigt, C., J. Lelieveld, H. Schlager, J. Schneider, J. Curtius, R. Meerkötter, D. Sauer, L. Bugliaro, B. Bohn, J. N. Crowley, T. Erbertseder, S. Groß, V. Hahn, Q. Li, M. Mertens, M. L. Pöhlker, A. Pozzer, U. Schumann, L. Tomsche, J. Williams, A. Zahn, M. Andreae, S. Borrmann, T. Bräuer, R. Dörich, A. Dörnbrack, A. Edtbauer, L. Ernle, H. Fischer, A. Giez, M. Granzin, V. Grewe, H. Harder, M. Heinritzi, B. A. Holanda, P. Jöckel, K. Kaiser, O. O. Krüger, J. Lucke, A. Marsing, A. Martin, S. Matthes, C. Pöhlker, U. Pöschl, S. Reifenberg, A. Ringsdorf, M. Scheibe, I. Tadic, M. Zauner-Wieczorek, R. Henke, and M. Rapp (2022): Cleaner Skies during the COVID-19 Lockdown. Bulletin of the American Meteorological Society 103 (8), E1796–E1827. doi: https://doi.org/10.1175/BAMS-D-21-0012.1.

Ziereis, H., P. Hoor, J.-U. Grooß, A. Zahn, G. Stratmann, P. Stock, M. Lichtenstern, J. Krause, V. Bense, A. Afchine, C. Rolf, W. Woiwode, M. Braun, J. Ungermann, A. Marsing, C. Voigt, A. Engel, B.-M. Sinnhuber, and H. Oelhaf (2022): Redistribution of total reactive nitrogen in the lowermost Arctic stratosphere during the coldwinter 2015/2016. Atmospheric Chemistry and Physics 22 (5), 3631–3654. doi: https://doi.org/10.5194/acp-22-3631-2022.