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A large-eddy model for cirrus clouds with explicit aerosol and ice microphysics and Lagrangian ice particle tracking

Sölch, Ingo and Kärcher, Bernd (2010) A large-eddy model for cirrus clouds with explicit aerosol and ice microphysics and Lagrangian ice particle tracking. Quarterly Journal of the Royal Meteorological Society, 136, pp. 2074-2093. DOI: 10.1002/qj.689.

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/qj.689/pdf

Abstract

We introduce a novel large-eddy model for cirrus clouds with explicit aerosol and ice microphysics, and validate its central components. A combined Eulerian/Lagrangian approach is used to simulate the formation and evolution of cirrus. While gas and size-resolved aerosol phases are treated over a fixed Eulerian grid similar to the dynamical and thermodynamical variables, the ice phase is treated by tracking a large number of simulation ice particles. The macroscopic properties of the ice phase are deduced from statistically analysing large samples of simulation ice particle properties. The new model system covers non-equilibrium growth of liquid supercooled aerosol particles, their homogeneous freezing, heterogeneous ice nucleation in the deposition or immersion mode, growth of ice crystals by deposition of water vapour, sublimation of ice crystals and their gravitational sedimentation, aggregation between ice crystals due to differential sedimentation, the effect of turbulent dispersion on ice particle trajectories, diabatic latent and radiative heating or cooling, and radiative heating or cooling of ice crystals. This suite of explicitly resolved physical processes enables the detailed simulation and analysis of the dynamical�microphysical�radiative feedbacks characteristic of cirrus. We draw special attention to the ice aggregation process which redistributes large ice crystals vertically and changes the ice particle size distributions accordingly. We find that aggregation of ice crystals is the key process to generate precipitation-sized ice crystals in stratiform cirrus. A process-oriented algorithm is developed for ice aggregation based on the trajectories and sedimentation velocities of simulation ice particles for use in the dynamically and microphysically complex, multi-dimensional large-eddy approach. By virtue of an idealized model set-up, designed to isolate the effect of aggregation on the cirrus development, we show that aggregation and its effect on the ice crystal size distribution in the model is consistent with a theoretical scaling relation, which was found to be in good agreement with in situ measurements

Document Type:Article
Title:A large-eddy model for cirrus clouds with explicit aerosol and ice microphysics and Lagrangian ice particle tracking
Authors:
AuthorsInstitution or Email of Authors
Sölch, Ingoingo.soelch@dlr.de
Kärcher, Berndbernd.kaercher@dlr.de
Date:2010
Journal or Publication Title:Quarterly Journal of the Royal Meteorological Society
Refereed publication:Yes
In Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:136
DOI:10.1002/qj.689
Page Range:pp. 2074-2093
Status:Published
Keywords:cloud-resolving models, large-eddy simulations, ice aggregation
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Atmosphären- und Klimaforschung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Ingo Sölch
Deposited On:06 Dec 2010 15:53
Last Modified:12 Dec 2013 21:08

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