TPChange
The Tropopause in a Changing Atmosphere - DFG TRR 301
TPChange is a DFG-funded Transregional Collaborative Research Center (CRC). Phase I started in July 2021 and ran until December 2025. Phase II runs from January 2026 until June 2029. TPChange focuses on the UTLS region (upper troposphere/lower stratosphere), with the goal to specify the impact of UTLS processes on composition, dynamics and ultimately on future climate and climate variability.
More information can be found on the TPChange homepage.
In phase II, our sub-project (A04, led by J. Schneider, Y. Li, and A. Vogel), focusses on the interactions between aerosol particles in the UTLS and the formation of cirrus clouds. This project contains three work packages (WP): In WP1, led by MPIC, we will use mass spectrometer data from past and upcoming aircraft-based measurements to extend the available data set on UTLS aerosol composition. This data set will allow for a better understanding of the aerosol properties, sources, and transport pathways in the UTLS. Additionally, the TPChange consortium will conduct a dedicated aircraft campaign (TPEx-II) with a small research aircraft (Learjet) equipped with a towed sensor shuttle. Here, A04 will measure small scale gradients of trace gases including water vapour, temperature, aerosol particles, and cirrus occurrence in the mid-latitude UTLS. In WP2, led by Yun Li of the Research Center Jülich, we will analyze these data with respect to cirrus occurrence, supporting modelling studies which up to now have difficulties resolving such a small vertical range. To achieve a better understanding of the interactions between aerosol particles and cirrus clouds, WP3 (led by Alexander Vogel of the Goethe University Frankfurt) will study the chemical processing and the ice nucleation ability of typical UTLS aerosol components during a laboratory campaign at the renewed cloud simulation chamber of KIT (Karlsruhe Institute of Technology). These measurements will specifically focus on particle emissions from aircraft, such as lubrication oil, under temperature conditions relevant for the UTLS.
In phase I, our sub-project (A04, led by F. Köllner, J. Schneider, and S. Borrmann) studied aerosol chemical composition and dynamics in the UTLS region from tropical monsoon to extratropical regions by using aircraft-based in-situ mass-spectrometric measurements. This included conducting a detailed analysis of particle composition data from previous and upcoming tropical missions with the research aircraft HALO, HIAPER, and Geophysica as well as studying small-scale aerosol dynamics in the extratropical UTLS.
Field campaigns:
ACCLIP campaign
In July-August 2022, AG Borrmann/Köllner participated in the NASA mission “ACCLIP“ (Asian Summer Monsoon Chemical and Climate Impact Project) with the mass spectrometer ERICA onboard the G-V „HIAPER“. The mission wss conducted out of South Korea and aimed for investigating the impacts of Asian gas and aerosol emissions on global chemistry and climate via the linkage of Asian Summer Monsoon (ASM) convection and associated large-scale dynamics.
PHILEAS campaign
Also associated to TPChange is the HALO mission „PHILEAS“ which is funded by the DFG-SPP 1294 „HALO“. It was conducted between August and October 2023. The first and third phases of PHILEAS took place out of Oberpfaffenhofen, Germany, the second (main) phase out of Anchorage, Alaska.
TPEx-I campaign (Learjet)
The main CRC field campaign in phase I (TPEx-I) was conducted in June 2024. We operated two UHSAS (one in the cabin, one in the towed sensor shuttle “TOSS”) to study small-scale aerosol gradients in the tropopause region. Furthermore, we operated the CARIBIC-AMS and a Grimm Sky-OPC in the Learjet cabin to measure aerosol composition.
People involved:
Phase I: F. Köllner, J. Schneider, S. Borrmann, O. Eppers, P. Joppe, J. Wilsch, P. Brauner, O. Appel, A. Hünig, S. Molleker, A. Dragoneas
Phase II: J. Schneider, N.N.
Instruments:
CARIBIC-AMS, UHSAS-A, UHSAS-G, ERICA
Results:
Bozem, H., Joppe, P., Li, Y., Emig, N., Afchine, A., Breuninger, A., Curtius, J., Hofmann, S., Ismayil, S., Kandler, K., Kunkel, D., Kutschka, A., Lachnitt, H.-C., Petzold, A., Richter, S., Röschenthaler, T., Rolf, C., Schneider, L., Schneider, J., Vogel, A., and Hoor, P.: The TropoPause Composition TOwed Sensor Shuttle (TPC-TOSS): a new airborne dual platform approach for atmospheric composition measurements at the tropopause, Atmos. Meas. Tech., 18, 6545–6568, https://doi.org/10.5194/amt-18-6545-2025, 2025.
Joppe, P., Schneider, J., Wilsch, J., Bozem, H., Breuninger, A., Curtius, J., Ebert, M., Emig, N., Hoor, P., Ismayil, S., Kandler, K., Kunkel, D., Kurth, I., Lachnitt, H.-C., Li, Y., Miltenberger, A., Richter, S., Rolf, C., Schneider, L., Schwenk, C., Spelten, N., Vogel, A. L., Cheng, Y., and Borrmann, S.: Transport of Biomass Burning Aerosol into the Extratropical Tropopause Region over Europe via Warm Conveyor Belt Uplift, Atmos. Chem. Phys., 25, 15077–15103, https://doi.org/10.5194/acp-25-15077-2025, 2025.
Schneider, J., Schulz, C., Rubach, F., Ludwig, A., Wilsch, J., Joppe, P., Gurk, C., Molleker, S., Poulain, L., Obersteiner, F., Gehrlein, T., Bönisch, H., Zahn, A., Hoor, P., Emig, N., Bozem, H., Borrmann, S., and Hermann, M.: CARIBIC-AMS: a fully automated aerosol mass spectrometer for operation on routine passenger flights (IAGOS-CARIBIC) – instrument description and first flight application, Atmos. Meas. Tech., 18, 5103–5128, https://doi.org/10.5194/amt-18-5103-2025, 2025.
Joppe, P., Schneider, J., Kaiser, K., Fischer, H., Hoor, P., Kunkel, D., Lachnitt, H.-C., Marsing, A., Röder, L., Schlager, H., Tomsche, L., Voigt, C., Zahn, A., and Borrmann, S.: The influence of extratropical cross-tropopause mixing on the correlation between ozone and sulfate aerosol in the lowermost stratosphere, Atmos. Chem. Phys., 24, 7499–7522, https://doi.org/10.5194/acp-24-7499-2024, 2024.