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@ARTICLE{Frey:17014,
      author       = {Frey, W. and Borrmann, S. and Kunkel, D. and Weigel, R. and
                      de Reus, M. and Schlager, H. and Roiger, A. and Voigt, C.
                      and Hoor, P. and Curtius, J. and Krämer, M. and Schiller,
                      C. and Volk, C.M. and Homan, M. and Fierli, F. and Di
                      Donfrancesco, G. and Ulanovsky, A. and Ravegnani, F. and
                      Sitnikov, N.M. and Viciani, S. and D'Amato, F. and Shur,
                      G.N. and Belyaev, G.V. and Law, K.S. and Cairo, F.},
      title        = {{I}n-situ measurements of tropical cloud properties in the
                      {W}est {A}frican monsoon: upper tropospheric ice clouds,
                      mesoscale convective system outflow, and subvisual cirrus},
      journal      = {Atmospheric chemistry and physics},
      volume       = {11},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {PreJuSER-17014},
      pages        = {5569 - 5590},
      year         = {2011},
      note         = {The SCOUT-O3 and SCOUT-AMMA projects were funded by the
                      European Commission through Contract
                      505390-GOCE-CT-2004-505390 and the EC Integrated Projects
                      AMMA-EU (Contract no. 004089-2). The M-55 Geophysica
                      campaign was supported by the EEIG-Geophysica Consortium,
                      CNRS-INSU, CNES, and EUFAR. Meteosat Second Generation data
                      were provided by the AMMA database
                      (http://aoc.amma-international.org/observation/satellite/)
                      and were processed including the flight tracks by Sylwester
                      Arabas from the University of Warsaw, Poland.Based on a
                      French initiative, AMMA was built by an international
                      scientific group and funded by a large number of agencies,
                      especially from France, the United Kingdom, the United
                      States, Africa, and - for us - German sources. It has been a
                      beneficiary of a major financial contribution from the
                      European Community Sixth Framework Programme (AMMA-EU).
                      Significant financial support for our activities with the
                      M-55 Geophysica in Australia and Burkina Faso also was
                      supplied by the Max Planck Society.For the CIP data
                      processing we gratefully acknowledge help from Aaron
                      Bansemer (NCAR, Boulder, Co, USA). For very helpful comments
                      on the manuscript we thank Jasmine Cetrone from the
                      University of Washington, Seattle, USA. We thank Stefano
                      Balestri, Ana Alfaro Martinez (ERS), and the pilots,
                      engineers, crew of the M-55 Geophysica. The local
                      authorities, scientists and staff in Ouagadougou (Burkina
                      Faso) were wonderful hosts, and we thank for their amazing
                      hospitality and support during this in many respects
                      challenging campaign in Burkina Faso, which for all of us
                      was a deeply moving life experience. Special thanks are due
                      to Toro Drabo from the University in Ouagadougou. We
                      grateful acknowledge the constructive and helpful comments
                      by Darrel Baumgardner, Grant Allen, and the two anonymous
                      referees.},
      abstract     = {In situ measurements of ice crystal size distributions in
                      tropical upper troposphere/lower stratosphere (UT/LS) clouds
                      were performed during the SCOUT-AMMA campaign over West
                      Africa in August 2006. The cloud properties were measured
                      with a Forward Scattering Spectrometer Probe (FSSP-100) and
                      a Cloud Imaging Probe (CIP) operated aboard the Russian high
                      altitude research aircraft M-55 Geophysica with the mission
                      base in Ouagadougou, Burkina Faso. A total of 117 ice
                      particle size distributions were obtained from the
                      measurements in the vicinity of Mesoscale Convective Systems
                      (MCS). Two to four modal lognormal size distributions were
                      fitted to the average size distributions for different
                      potential temperature bins. The measurements showed
                      proportionately more large ice particles compared to former
                      measurements above maritime regions. With the help of trace
                      gas measurements of NO, NOy, CO2, CO, and O-3 and satellite
                      images, clouds in young and aged MCS outflow were
                      identified. These events were observed at altitudes of 11.0
                      km to 14.2 km corresponding to potential temperature levels
                      of 346K to 356 K. In a young outflow from a developing MCS
                      ice crystal number concentrations of up to (8.3 +/- 1.6)
                      cm(-3) and rimed ice particles with maximum dimensions
                      exceeding 1.5mm were found. A maximum ice water content of
                      0.05 gm(-3) was observed and an effective radius of about 90
                      mu m. In contrast the aged outflow events were more diluted
                      and showed a maximum number concentration of 0.03 cm(-3), an
                      ice water content of 2.3x10(-4) gm(-3), an effective radius
                      of about 18 mu m, while the largest particles had a maximum
                      dimension of 61 mu m.Close to the tropopause subvisual
                      cirrus were encountered four times at altitudes of 15 km to
                      16.4 km. The mean ice particle number concentration of these
                      encounters was 0.01 cm(-3) with maximum particle sizes of
                      130 mu m, and the mean ice water content was about
                      1.4x10(-4) gm(-3). All known in situ measurements of
                      subvisual tropopause cirrus are compared and an exponential
                      fit on the size distributions is established for modelling
                      purposes.A comparison of aerosol to ice crystal number
                      concentrations, in order to obtain an estimate on how many
                      ice particles may result from activation of the present
                      aerosol, yielded low ratios for the subvisual cirrus cases
                      of roughly one cloud particle per 30 000 aerosol particles,
                      while for the MCS outflow cases this resulted in a high
                      ratio of one cloud particle per 300 aerosol particles.},
      keywords     = {J (WoSType)},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK491},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000291939800003},
      doi          = {10.5194/acp-11-5569-2011},
      url          = {https://juser.fz-juelich.de/record/17014},
}