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| Titel |
A Microphysics Guide to Cirrus Clouds - Part I: Cirrus Types |
| VerfasserIn |
Martina Krämer, Christian Rolf, Anna Luebke, Armin Afchine, Nicole Spelten, Anja Costa, Jessica Meyer, Martin Zöger, Jessica Smith, Herman Robert, Bernhard Buchholz, Ebert Volker, Darrel Baumgardner, Stephan Borrmann, Marcus Klingebiel, Avallone Linnea |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250132893
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| Publikation (Nr.) |
 EGU/EGU2016-13440.pdf |
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| Zusammenfassung |
| The microphysical and radiative properties of cirrus clouds continue to be beyond
understanding and thus still represent one of the largest uncertainties in the prediction of the
Earth’s climate (IPCC, 2013). Our study provides a guide to cirrus microphysics, which is
compiled from an extensive set of model simulations, covering the broad range of
atmospheric conditions for cirrus formation and evolution (Krämer et al., 2015, ACPD). The
model results are portrayed in the same parameter space as field measurements, i.e. in the Ice
Water Content-Temperature (IWC-T) parameter space. We validate this cirrus analysis
approach by evaluating cirrus data sets from seventeen aircraft campaigns, conducted in the
last fifteen years, spending about 94 h in cirrus over Europe, Australia, Brazil as well as
Southern and Northern America. Altogether, the approach of this study is to track cirrus
IWC development with temperature by means of model simulations, compare with
observations and then assign, to a certain degree, cirrus microphysics to the observations.
Indeed, the field observations show characteristics expected from the simulated cirrus
guide. For example, high/low IWCs are found together with high/low ice crystal
concentrations.
An important finding from our study is the classification of two types of cirrus with
differing formation mechanisms and microphysical properties: the first cirrus type is rather
thin with lower IWCs and forms directly as ice (in-situ origin cirrus). The second type
consists predominantly of thick cirrus originating from mixed phase clouds (i.e. via freezing
of liquid droplets – liquid origin cirrus), which are completely glaciated while lifting to the
cirrus formation temperature region (< 235 K). In the European field campaigns, in-situ
origin cirrus occur frequently at slow updrafts in low and high pressure systems, but also in
conjunction with faster updrafts. Also, liquid origin cirrus mostly related to warm
conveyor belts are found. In the US and tropical campaigns, thick liquid origin
cirrus which are formed in large convective systems are detected more frequently. |
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