Closure studies in mixed-phase and ice clouds over Cyprus: is there agreement between ice nuclei and ice crystal number concentration?
Date Issued
March 2018
Abstract
Combined aerosol and cloud measurements with polarization/Raman lidar and
wind Doppler lidar were performed during field campaigns in Cyprus in 2015 and 2017/18.
One of the goals was to investigate the relationship between the ice-nucleating particle
concentration (INPC) outside mixed-phase and cirrus clouds and the ice crystal number
concentration (ICNC) within the observed altocumulus and cirrus layers or just below cloud
base (in the virga region). In a cooperation of the Cyprus University of Technology (CUT) and
the Leibniz Institute for Tropospheric Research (TROPOS) we developed a new technique to
derived height profiles of INPC from polarization lidar measurements. The Doppler lidar, on
the other hand, measures the fall velocity of ice crystals from which the effective size of
crystals can be estimated and together with the optical properties (from the polarization lidar
observations) the ice crystal number concentration can be estimated as well. We present case
studies of INPC profiles and ICNC estimates for altocumulus layers (between 5-7 km height)
and in cirrus clouds (between 9-10 km height). Good agreement, but also strong deviations
between the INPC and ICNC values were found. This will be discussed in the presentation.
wind Doppler lidar were performed during field campaigns in Cyprus in 2015 and 2017/18.
One of the goals was to investigate the relationship between the ice-nucleating particle
concentration (INPC) outside mixed-phase and cirrus clouds and the ice crystal number
concentration (ICNC) within the observed altocumulus and cirrus layers or just below cloud
base (in the virga region). In a cooperation of the Cyprus University of Technology (CUT) and
the Leibniz Institute for Tropospheric Research (TROPOS) we developed a new technique to
derived height profiles of INPC from polarization lidar measurements. The Doppler lidar, on
the other hand, measures the fall velocity of ice crystals from which the effective size of
crystals can be estimated and together with the optical properties (from the polarization lidar
observations) the ice crystal number concentration can be estimated as well. We present case
studies of INPC profiles and ICNC estimates for altocumulus layers (between 5-7 km height)
and in cirrus clouds (between 9-10 km height). Good agreement, but also strong deviations
between the INPC and ICNC values were found. This will be discussed in the presentation.
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