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@ARTICLE{Hoffmann:906976,
      author       = {Hoffmann, Lars and Spang, Reinhold},
      title        = {{A}n assessment of tropopause characteristics of the {ERA}5
                      and {ERA}-{I}nterim meteorological reanalyses},
      journal      = {Atmospheric chemistry and physics},
      volume       = {22},
      number       = {6},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2022-01789},
      pages        = {4019 - 4046},
      year         = {2022},
      abstract     = {The tropopause layer plays a key role in manifold processes
                      in atmospheric chemistry and physics. Here we compare the
                      representation and characteristics of the lapse rate
                      tropopause according to the definition of the World
                      Meteorological Organization (WMO) as estimated from European
                      Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis
                      data. Our study is based on 10-year records (2009 to 2018)
                      of ECMWF's state-of-the-art reanalysis ERA5 and its
                      predecessor ERA-Interim. The intercomparison reveals notable
                      differences between ERA5 and ERA-Interim tropopause data, in
                      particular on small spatiotemporal scales. The monthly mean
                      differences of ERA5 minus ERA-Interim tropopause heights
                      vary between −300 m at the transition from the tropics
                      to the extratropics (near 30∘ S and 30∘ N) to
                      150 m around the Equator. Mean tropopause temperatures are
                      mostly lower in ERA5 than in ERA-Interim, with a maximum
                      difference of up to −1.5 K in the tropics. Monthly
                      standard deviations of tropopause heights of ERA5 are up to
                      350 m or $60 \%$ larger than for ERA-Interim. Monthly
                      standard deviations of tropopause temperatures of ERA5
                      exceed those of ERA-Interim by up to 1.5 K or $30 \%.$
                      The occurrence frequencies of double-tropopause events in
                      ERA5 exceed those of ERA-Interim by up to 25 percentage
                      points at middle latitudes. We attribute the differences
                      between the ERA5 and ERA-Interim tropopause data and the
                      larger, more realistic variability of ERA5 to improved
                      spatiotemporal resolution and better representation of
                      geophysical processes in the forecast model as well as
                      improvements in the data assimilation scheme and the
                      utilization of additional observations in ERA5. The improved
                      spatiotemporal resolution of ERA5 allows for a better
                      representation of mesoscale features, in particular of
                      gravity waves, which affect the temperature profiles in the
                      upper troposphere and lower stratosphere (UTLS) and thus the
                      tropopause height estimates. We evaluated the quality of the
                      ERA5 and ERA-Interim reanalysis tropopause data by
                      comparisons with COSMIC and MetOp Global Positioning System
                      (GPS) satellite observations as well as high-resolution
                      radiosonde profiles. The comparison indicates an uncertainty
                      of the first tropopause for ERA5 (ERA-Interim) of about
                      ±150 to ±200 m (±250 m) based on radiosonde data and
                      ±120 to ±150 m (±170 to ±200 m) based on the
                      coarser-resolution GPS data at different latitudes.
                      Consequently, ERA5 will provide more accurate information
                      than ERA-Interim for future tropopause-related studies.},
      cin          = {JSC / IEK-7 / CASA},
      ddc          = {550},
      cid          = {I:(DE-Juel1)JSC-20090406 / I:(DE-Juel1)IEK-7-20101013 /
                      I:(DE-Juel1)CASA-20230315},
      pnm          = {5111 - Domain-Specific Simulation Data Life Cycle Labs
                      (SDLs) and Research Groups (POF4-511) / 2112 - Climate
                      Feedbacks (POF4-211) / DFG project 410579391 - Transportwege
                      für Aerosol und Spurengase im Asiatischen Monsun in der
                      oberen Troposphäre und unteren Stratosphäre},
      pid          = {G:(DE-HGF)POF4-5111 / G:(DE-HGF)POF4-2112 /
                      G:(GEPRIS)410579391},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000776518900001},
      doi          = {10.5194/acp-22-4019-2022},
      url          = {https://juser.fz-juelich.de/record/906976},
}