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@ARTICLE{KienastSjgren:820661,
      author       = {Kienast-Sjögren, Erika and Rolf, Christian and Seifert,
                      Patric and Krieger, Ulrich K. and Luo, Bei P. and Krämer,
                      Martina and Peter, Thomas},
      title        = {{C}limatological and radiative properties of midlatitude
                      cirrus clouds derived by automatic evaluation of lidar
                      measurements},
      journal      = {Atmospheric chemistry and physics},
      volume       = {16},
      number       = {12},
      issn         = {1680-7324},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2016-05930},
      pages        = {7605 - 7621},
      year         = {2016},
      abstract     = {Cirrus, i.e., high, thin clouds that are fully glaciated,
                      play an important role in the Earth's radiation budget as
                      they interact with both long- and shortwave radiation and
                      affect the water vapor budget of the upper troposphere and
                      stratosphere. Here, we present a climatology of midlatitude
                      cirrus clouds measured with the same type of ground-based
                      lidar at three midlatitude research stations: at the Swiss
                      high alpine Jungfraujoch station (3580 m a.s.l.), in
                      Zürich (Switzerland, 510 m a.s.l.), and in Jülich
                      (Germany, 100 m a.s.l.). The analysis is based on
                      13 000 h of measurements from 2010 to 2014. To
                      automatically evaluate this extensive data set, we have
                      developed the Fast LIdar Cirrus Algorithm (FLICA), which
                      combines a pixel-based cloud-detection scheme with the
                      classic lidar evaluation techniques. We find mean cirrus
                      optical depths of 0.12 on Jungfraujoch and of 0.14 and 0.17
                      in Zürich and Jülich, respectively.Above Jungfraujoch,
                      subvisible cirrus clouds (τ < 0.03) have been observed
                      during $6 \%$ of the observation time, whereas above
                      Zürich and Jülich fewer clouds of that type were observed.
                      Cirrus have been observed up to altitudes of
                      14.4 km a.s.l. above Jungfraujoch, whereas they have
                      only been observed to about 1 km lower at the other
                      stations. These features highlight the advantage of the
                      high-altitude station Jungfraujoch, which is often in the
                      free troposphere above the polluted boundary layer, thus
                      enabling lidar measurements of thinner and higher clouds. In
                      addition, the measurements suggest a change in cloud
                      morphology at Jungfraujoch above ∼ 13 km, possibly
                      because high particle number densities form in the observed
                      cirrus clouds, when many ice crystals nucleate in the high
                      supersaturations following rapid uplifts in lee waves above
                      mountainous terrain.The retrieved optical properties are
                      used as input for a radiative transfer model to estimate the
                      net cloud radiative forcing, CRFNET, for the analyzed cirrus
                      clouds. All cirrus detected here have a positive CRFNET.
                      This confirms that these thin, high cirrus have a warming
                      effect on the Earth's climate, whereas cooling clouds
                      typically have cloud edges too low in altitude to satisfy
                      the FLICA criterion of temperatures below −38 °C. We
                      find CRFNET = 0.9 W m−2 for Jungfraujoch and
                      1.0 W m−2 (1.7 W m−2) for Zürich (Jülich).
                      Further, we calculate that subvisible cirrus (τ < 0.03)
                      contribute about $5 \%,$ thin cirrus
                      (0.03 < τ < 0.3) about $45 \%,$ and opaque cirrus
                      (0.3 < τ) about $50 \%$ of the total cirrus radiative
                      forcing.},
      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},
      UT           = {WOS:000379417300008},
      doi          = {10.5194/acp-16-7605-2016},
      url          = {https://juser.fz-juelich.de/record/820661},
}