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@ARTICLE{BartolomeGarcia:892450,
      author       = {Bartolome Garcia, Irene and Spang, Reinhold and Ungermann,
                      Jörn and Griessbach, Sabine and Krämer, Martina and
                      Höpfner, Michael and Riese, Martin},
      title        = {{O}bservation of cirrus clouds with {GLORIA} during the
                      {WISE} campaign: detection methods and cirrus
                      characterization},
      journal      = {Atmospheric measurement techniques},
      volume       = {14},
      number       = {4},
      issn         = {1867-8548},
      address      = {Katlenburg-Lindau},
      publisher    = {Copernicus},
      reportid     = {FZJ-2021-02088},
      pages        = {3153 - 3168},
      year         = {2021},
      abstract     = {Cirrus clouds contribute to the general radiation budget of
                      the Earth and play an important role in climate projections.
                      Of special interest are optically thin cirrus clouds close
                      to the tropopause due to the fact that their impact is not
                      yet well understood. Measuring these clouds is challenging
                      as both high spatial resolution as well as a very high
                      detection sensitivity are needed. These criteria are
                      fulfilled by the infrared limb sounder GLORIA (Gimballed
                      Limb Observer for Radiance Imaging of the Atmosphere). This
                      study presents a characterization of observed cirrus clouds
                      using the data obtained by GLORIA aboard the German research
                      aircraft HALO during the WISE (Wave-driven ISentropic
                      Exchange) campaign in September and October 2017. We
                      developed an optimized cloud detection method based on the
                      cloud index and the extinction coefficient retrieved at the
                      microwindow 832.4–834.4 cm−1. We derived
                      macro-physical characteristics of the detected cirrus clouds
                      such as cloud top height, cloud bottom height, vertical
                      extent and cloud top position with respect to the
                      tropopause. The fraction of cirrus clouds detected above the
                      tropopause is on the order of $13 \%$ to $27 \%.$ In
                      general, good agreement with the clouds predicted by the
                      ERA5 reanalysis dataset is obtained. However, cloud
                      occurrence is $≈ 50 \%$ higher in the observations for
                      the region close to and above the tropopause. Cloud bottom
                      heights are also detected above the tropopause. However,
                      considering the uncertainties, we cannot confirm the
                      formation of unattached cirrus layers above the tropopause.},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {211 - Die Atmosphäre im globalen Wandel (POF4-211) / 2A3 -
                      Remote Sensing (CARF - CCA) (POF4-2A3) / DFG project
                      316588738 - Zirrus Wolken in der extratropsichen
                      Tropopausen- und unteren Stratosphären-Region},
      pid          = {G:(DE-HGF)POF4-211 / G:(DE-HGF)POF4-2A3 /
                      G:(GEPRIS)316588738},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000646583600001},
      doi          = {10.5194/amt-14-3153-2021},
      url          = {https://juser.fz-juelich.de/record/892450},
}