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@PHDTHESIS{Costa:829847,
author = {Costa, Anja},
title = {{M}ixed-phase and ice cloud observations with
{NIXE}-{CAPS}},
volume = {397},
school = {Universität Wuppertal},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2017-03469},
isbn = {978-3-95806-273-3},
series = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
Umwelt / Energy $\&$ Environment},
pages = {xviii, 117 S.},
year = {2017},
note = {Universität Wuppertal, Diss., 2017},
abstract = {Clouds are a main component in the climate system. They
influence the energy balance of the atmosphere by changing
the earth’s albedo and greenhouse effect, and redistribute
energy by releasing and consuming latent heat in cloud
particle nucleation and dissolution processes. Climate
models therefore react sensitively on the implemented cloud
parametrizations, which have to be under constant review to
implement new insights into cloud formation and
evolutionprocesses. Ice clouds pose a particular challenge
for simulations: In mid-level and high clouds, several
possible ways for cloud glaciation and ice particle
formation compete. These processes produce particles that
vary strongly in habits, concentrations and radiative
properties. As long as it remains unclear which processes
are active, how their influence is distributed globally, how
these processes might change due to global warming, and what
the properties of the produced ice particles are, ice clouds
will remain a significant factor of uncertainty in climate
predictions. Over the last years, a number of studies has
been performed to examine these questions. The Jülich
instrument NIXE-CAPS has contributed a unique ice particle
concentration dataset that was used to evaluate global cloud
simulations. This thesis presents the extension of the
aforesaid dataset into mid-level clouds, where the
partitioning of ice and supercooled liquid water becomes
increasingly relevant. NIXE-CAPS provides three relevant
characteristics of the observed clouds: particle number
concentrations, particle size distributions and particle
asphericity - especially of small particles with diameters
below 50 $\mu$m, which have been rarely analysed so far. The
analysis of this data set was extended, evaluated and
accelerated in the course of this work: instrument
comparisons, error estimations and new corrections
complement earlier works with NIXE-CAPS. The improved
algorithms allowed a reanalysis of previous measurements and
resulted in a consistent data set covering 39 hours of
measurements within high clouds (cirrus) and over 38 hours
within mid-level clouds. With the NIXE-CAPS measurements,
the following tasks were performed: The proportions of
liquid, mixed-phase, ’small ice’, and ’large ice’
clouds were resolved for Arctic, mid-latitude and tropical
observations. Also, the new model CLaMS-Ice was evaluated
and improved with respect to its microphysical accuracy: It
provides detailed cirrus cloud simulations over a wide range
of meteorological conditions. It can thus be used for
large-scale cirrus cloud simulations which is expected to
lead to new insights regarding the global cirrus cloud
cover’s climatological characteristics.},
cin = {IEK-7},
cid = {I:(DE-Juel1)IEK-7-20101013},
pnm = {244 - Composition and dynamics of the upper troposphere and
middle atmosphere (POF3-244) / HITEC - Helmholtz
Interdisciplinary Doctoral Training in Energy and Climate
Research (HITEC) (HITEC-20170406)},
pid = {G:(DE-HGF)POF3-244 / G:(DE-Juel1)HITEC-20170406},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/829847},
}