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Volume 18, issue 19 | Copyright
Atmos. Chem. Phys., 18, 14351-14370, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 09 Oct 2018

Research article | 09 Oct 2018

Ice crystal number concentration estimates from lidar–radar satellite remote sensing – Part 2: Controls on the ice crystal number concentration

Edward Gryspeerdt1, Odran Sourdeval2,a, Johannes Quaas2, Julien Delanoë3, Martina Krämer4, and Philipp Kühne2 Edward Gryspeerdt et al.
  • 1Space and Atmospheric Physics Group, Imperial College London, London, UK
  • 2Institute for Meteorology, Universität Leipzig, Leipzig, Germany
  • 3Laboratoire Atmosphères, Milieux, Observations Spatiales/IPSL/UVSQ/CNRS/UPMC, Guyancourt, France
  • 4Forschungszentrum Jülich, Institut für Energie und Klimaforschung (IEK-7), Jülich, Germany
  • anow at: Laboratoire d'Optique Atmosphérique, Université Lille 1, Villeneuve d'Ascq, France

Abstract. The ice crystal number concentration (Ni) is a key property of ice clouds, both radiatively and microphysically. Due to sparse in situ measurements of ice cloud properties, the controls on the Ni have remained difficult to determine. As more advanced treatments of ice clouds are included in global models, it is becoming increasingly necessary to develop strong observational constraints on the processes involved.

This work uses the DARDAR-Nice Ni retrieval described in Part 1 to investigate the controls on the Ni at a global scale. The retrieved clouds are separated by type. The effects of temperature, proxies for in-cloud updraft and aerosol concentrations are investigated. Variations in the cloud top Ni (Ni(top)) consistent with both homogeneous and heterogeneous nucleation are observed along with differing relationships between aerosol and Ni(top) depending on the prevailing meteorological situation and aerosol type. Away from the cloud top, the Ni displays a different sensitivity to these controlling factors, providing a possible explanation for the low Ni sensitivity to temperature and ice nucleating particles (INP) observed in previous in situ studies.

This satellite dataset provides a new way of investigating the response of cloud properties to meteorological and aerosol controls. The results presented in this work increase our confidence in the retrieved Ni and will form the basis for further study into the processes influencing ice and mixed phase clouds.

Publications Copernicus
Short summary
The concentration of ice crystals in a cloud affects both the properties and the life cycle of the cloud. This work uses a new satellite retrieval to investigate controls on the ice crystal concentration at a global scale. Both temperature and vertical wind speed in a cloud have a strong impact on the concentration of ice crystals. The ice crystal number is also related to the aerosol environment; defining this relation opens up new ways to investigate human impacts on clouds and the climate.
The concentration of ice crystals in a cloud affects both the properties and the life cycle of...