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@ARTICLE{Eichinger:1016801,
      author       = {Eichinger, Roland and Rhode, Sebastian and Garny, Hella and
                      Preusse, Peter and Pisoft, Petr and Kuchař, Aleš and
                      Jöckel, Patrick and Kerkweg, Astrid and Kern, Bastian},
      title        = {{E}mulating lateral gravity wave propagation in a global
                      chemistry–climate model ({EMAC} v2.55.2) through
                      horizontal flux redistribution},
      journal      = {Geoscientific model development},
      volume       = {16},
      number       = {19},
      issn         = {1991-959X},
      address      = {Katlenburg-Lindau},
      publisher    = {Copernicus},
      reportid     = {FZJ-2023-03785},
      pages        = {5561 - 5583},
      year         = {2023},
      abstract     = {The columnar approach of gravity wave (GW)
                      parameterisations in weather and climate models has been
                      identified as a potential reason for dynamical biases in
                      middle-atmospheric dynamics. For example, GW momentum flux
                      (GWMF) discrepancies between models and observations at
                      60∘ S arising through the lack of horizontal orographic
                      GW propagation are suspected to cause deficiencies in
                      representing the Antarctic polar vortex. However, due to the
                      decomposition of the model domains onto different computing
                      tasks for parallelisation, communication between horizontal
                      grid boxes is computationally extremely expensive, making
                      horizontal propagation of GWs unfeasible for global
                      chemistry–climate simulations.To overcome this issue, we
                      present a simplified solution to approximate horizontal GW
                      propagation through redistribution of the GWMF at one single
                      altitude by means of tailor-made redistribution maps. To
                      generate the global redistribution maps averaged for each
                      grid box, we use a parameterisation describing orography as
                      a set of mountain ridges with specified location,
                      orientation and height combined with a ray-tracing model
                      describing lateral propagation of so-generated mountain
                      waves. In the global chemistry–climate model (CCM) EMAC
                      (ECHAM MESSy Atmospheric Chemistry), these maps then allow
                      us to redistribute the GW momentum flux horizontally at one
                      level, obtaining an affordable overhead of computing
                      resources. The results of our simulations show GWMF and drag
                      patterns that are horizontally more spread out than with the
                      purely columnar approach; GWs are now also present above the
                      ocean and regions without mountains. In this paper, we
                      provide a detailed description of how the redistribution
                      maps are computed and how the GWMF redistribution is
                      implemented in the CCM. Moreover, an analysis shows why
                      15 km is the ideal altitude for the redistribution. First
                      results with the redistributed orographic GWMF provide clear
                      evidence that the redistributed GW drag in the Southern
                      Hemisphere has the potential to modify and improve Antarctic
                      polar vortex dynamics, thereby paving the way for enhanced
                      credibility of CCM simulations and projections of polar
                      stratospheric ozone.},
      cin          = {IEK-8 / IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013 / I:(DE-Juel1)IEK-7-20101013},
      pnm          = {2111 - Air Quality (POF4-211) / 2112 - Climate Feedbacks
                      (POF4-211)},
      pid          = {G:(DE-HGF)POF4-2111 / G:(DE-HGF)POF4-2112},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:001161827800001},
      doi          = {10.5194/gmd-16-5561-2023},
      url          = {https://juser.fz-juelich.de/record/1016801},
}