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@INPROCEEDINGS{Turhal:1045730,
      author       = {Turhal, Katharina and Ploeger, Felix and Clemens, Jan
                      Heinrich and Birner, Thomas and Weyland, Franziska and
                      Konopka, Paul and Hoor, Peter and Podglajen, Aurelien},
      title        = {{V}ariability in {U}pper {T}roposphere – {L}ower
                      {S}tratosphere transport from model age of air},
      reportid     = {FZJ-2025-03570},
      year         = {2025},
      abstract     = {Understanding transport pathways and timescales in the
                      upper troposphere and lower stratosphere (UTLS) is essential
                      for assessing changes in atmospheric composition,
                      particularly for radiatively active trace gases. These
                      species play a crucial role in the Earth’s radiation
                      budget, yet their variability and trends remain uncertain
                      due to incomplete representation of transport processes in
                      current models.To address this, we analyze the evolution of
                      UTLS transport over the past four decades by determining the
                      Age of Air—the transit time from the troposphere into the
                      stratosphere. We employ the Chemical Lagrangian Model of the
                      Stratosphere (CLaMS), driven by ERA5 reanalysis data from
                      1979 to 2024, to investigate these research questions: 1.
                      What does the climatology of Age of Air reveal about
                      underlying transport mechanisms? 2. How have transport
                      pathways and timescales changed over the last 40 years? 3.
                      How do interannual drivers such as the Quasi-Biennial
                      Oscillation (QBO) and El Niño-Southern Oscillation (ENSO)
                      influence transport variability? 4. How do composition
                      changes in the UTLS relate to observed and modeled trends in
                      the Brewer-Dobson circulation (BDC), the tropopause, and
                      subtropical transport barriers?We assess trends, seasonal
                      cycles, and interannual variations in high-resolution Age of
                      Air spectra, mean Age of Air and the mass fractions of young
                      air. Our findings demonstrate significant improvements in
                      the representation of fast transport processes, particularly
                      in the tropics, enabled by the higher temporal resolution of
                      the simulated age spectra compared to previous studies. In
                      particular, fine-scale structure and sharp peaks in the age
                      spectra relate to fast transport processes. These insights
                      contribute to a more robust understanding of UTLS transport
                      dynamics and their role in shaping atmospheric composition
                      and climate variability.},
      month         = {Jul},
      date          = {2025-07-20},
      organization  = {Busan IAMAS-IACS-IAPSO Joint Assembly
                       2025, Busan (South Korea), 20 Jul 2025
                       - 25 Jul 2025},
      subtyp        = {After Call},
      cin          = {ICE-4},
      cid          = {I:(DE-Juel1)ICE-4-20101013},
      pnm          = {2112 - Climate Feedbacks (POF4-211) / DFG project
                      G:(GEPRIS)428312742 - TRR 301: Die Tropopausenregion in
                      einer Atmosphäre im Wandel (428312742)},
      pid          = {G:(DE-HGF)POF4-2112 / G:(GEPRIS)428312742},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/1045730},
}