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@ARTICLE{Charlesworth:884897,
      author       = {Charlesworth, Edward J. and Dugstad, Ann-Kristin and
                      Fritsch, Frauke and Jöckel, Patrick and Ploeger, Felix},
      title        = {{I}mpact of {L}agrangian {T}ransport on
                      {L}ower-{S}tratospheric {T}ransport {T}ime {S}cales in a
                      {C}limate {M}odel},
      journal      = {Atmospheric chemistry and physics / Discussions},
      volume       = {458},
      issn         = {1680-7367},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2020-03302},
      pages        = {},
      year         = {2020},
      abstract     = {We investigate the impact of model trace gas transport
                      schemes on the representation of transport processes in the
                      upper troposphere and lower stratosphere. Towards this end,
                      the Chemical Lagrangian Model of the Stratosphere (CLaMS)
                      was coupled to the ECHAM/MESSy Atmospheric Chemistry (EMAC)
                      model and results from the two transport schemes were
                      compared. Advection in CLaMS was driven by the EMAC
                      simulation winds and thereby the only differences in
                      transport between the two sets of results were caused by
                      differences in the transport schemes. To analyze the time
                      scales of large-scale transport, multiple
                      tropical-surface-emitted tracer pulses were performed to
                      calculate age of air spectra, while smaller-scale transport
                      was analyzed via idealized, radioactively-decaying tracers
                      emitted in smaller regions (nine grid cells) within the
                      stratosphere. The results show that stratospheric transport
                      barriers are significantly stronger for Lagrangian
                      EMAC-CLaMS transport due to reduced numerical diffusion. In
                      particular, stronger tracer gradients emerge around the
                      polar vortex, at the subtropical jets, and at the edge of
                      the tropical pipe. Inside the polar vortex, the more
                      diffusive EMAC flux-form semi-Lagrangian transport scheme
                      results in a substantially higher amount of air with ages
                      from 0 to 2 years (up to a factor 5 higher). In the
                      lowermost stratosphere, air is much younger in EMAC, owing
                      to stronger diffusive cross-tropopause transport.
                      Conversely, EMAC-CLaMS shows a summertime lowermost
                      stratosphere age inversion – a layer of older air residing
                      below younger air (an eave). This pattern is caused by
                      strong poleward transport above the subtropical jet, and is
                      entirely blurred by diffusive cross-tropopause transport in
                      EMAC. Potential consequences from the choice of the
                      transport scheme on CCM and geoengineering simulations are
                      discussed.},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {244 - Composition and dynamics of the upper troposphere and
                      middle atmosphere (POF3-244)},
      pid          = {G:(DE-HGF)POF3-244},
      typ          = {PUB:(DE-HGF)16},
      doi          = {10.5194/acp-2020-458},
      url          = {https://juser.fz-juelich.de/record/884897},
}