1,1,1,1,1,1,2,3,3,6,7,4- 1Johannes Gutenberg University Mainz, Institute for Atmospheric Physics, Physics, Mainz, Germany (hoor@uni-mainz.de)
- 2Insttute for Atmospheric and Environmental Sciences, Goethe University, Frankfurt/Main, Germany
- 3Institute for Atmospheric Chemistry, Max-Planck Institute for Chemistry, Mainz, Germany
- 4Institute of Climate and Energy Systems (ICE-4), Forschungszentum Jülich, Germany
- 5Institute for Atmospheric and Environmental Research, Bergische Universität, Wuppertal, Germany
- 6Institute of Meteorology and Climate and Research (IMK-ASF), Karlsruhe Institute for Technology, Karlsruhe, Germany
- 7Institute for Atmospheric Physics, German Aerospace Center, DLR, Wessling, Germany
The composition of the UTLS plays a critical role in shaping Earth’s radiation budget, large-scale dynamics, and not least surface weather and air quality. Yet, its high spatiotemporal variability - driven by diverse transport and mixing pathways on different time scales - remains poorly quantified, limiting predictive capabilities.
In this study, we use a trace gas budget approach to quantify contributions of different transport and mixing pathways into the lowermost stratosphere (LMS). Especially the contribution of aged and partially chemically processed polar vortex air masses is difficult to determine due to isentropic transport and mixing with air masses originating in the extratropical troposphere.
We present an empirical approach using in-situ N2O, NOy, SF6 and CO measurements from three winter-to-spring aircraft campaigns using the HALO aircraft (ASCCI 2025, SouthTRAC 2019 and POLSTRACC 2016). We apply the contrasting trace gas lifetimes (N₂O: ~100 years; CO: ~months) to partition LMS air masses into three dynamically distinct fractions constituting of 1) a tropospheric fraction of air transported and mixed across the extratropical tropopause, 2) a stratospheric fraction, originating from diabatic downwelling and 3) a further separation of the stratospheric contribution accounting for vortex and extra-vortex air.
We present climatologies of the individual contributions, comparing the three campaigns. A focus is set on the evolution of the vortex fraction from winter to spring. Furthermore, robust validation against independent CH₄, SF6 and NOy measurements builds confidence in the framework’s ability to reconstruct distributions of other long-lived species from the three resolved fractions. We furthermore argue that the N2O-CO budget approach provides a quantitative, observation-based separation of LMS transport pathways, enabling improved evaluation of climate models and process studies.
How to cite: Hoor, P., Weyland, F., Bense, V., Bozem, H., Blumenroth, J., Emig, N., Kunkel, D., Lachnitt, H.-C., Engel, A., Joppe, P., Ort, L., Lauther, V., Ploeger, F., Sinnhuber, B.-M., Strobel, J., Volk, M., Ziereis, H., Zahn, A., and Riese, M.: Empirical air mass budgets in the winter-spring lower stratosphere from in-situ measurements during ASCCI, SouthTRAC and POLSTRACC missions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16654, https://doi.org/10.5194/egusphere-egu26-16654, 2026.
