Relationships between Immersion Freezing and Crystal Habit for Arctic Mixed-Phase Clouds—A Numerical Study
The number concentration of ice particles in Arctic mixed-phase clouds is a major controlling factor of cloud lifetime. The relationships between ice nucleation mode and ice crystal habit development are not yet constrained by observations. This study uses a habit-predicting microphysical scheme wit...
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Online Access: | http://www.osti.gov/servlets/purl/1673391 https://www.osti.gov/biblio/1673391 https://doi.org/10.1175/jas-d-20-0078.1 |
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ftosti:oai:osti.gov:1673391 2023-07-30T04:01:19+02:00 Relationships between Immersion Freezing and Crystal Habit for Arctic Mixed-Phase Clouds—A Numerical Study Hashino, Tempei de Boer, Gijs Okamoto, Hajime Tripoli, Gregory J. 2020-10-19 application/pdf http://www.osti.gov/servlets/purl/1673391 https://www.osti.gov/biblio/1673391 https://doi.org/10.1175/jas-d-20-0078.1 unknown http://www.osti.gov/servlets/purl/1673391 https://www.osti.gov/biblio/1673391 https://doi.org/10.1175/jas-d-20-0078.1 doi:10.1175/jas-d-20-0078.1 2020 ftosti https://doi.org/10.1175/jas-d-20-0078.1 2023-07-11T09:48:23Z The number concentration of ice particles in Arctic mixed-phase clouds is a major controlling factor of cloud lifetime. The relationships between ice nucleation mode and ice crystal habit development are not yet constrained by observations. This study uses a habit-predicting microphysical scheme within a 3D large-eddy simulation model to evaluate the relationship between immersion freezing and ice habit in a simulated Arctic mixed-phase cloud case. Three immersion freezing parameterizations are considered: a volume-dependent freezing scheme (VF), a parameterization limited to activated droplets (C-AC), and a parameterization limited to coarse aerosol particles (C-CM). Both C-AC and C-CM are based on classical nucleation theory. The freezing rate with VF is found to be greater in downdraft regions than in updraft regions due to the downdraft having a higher number concentration of large droplets. Here, the C-AC cases show active freezing of small droplets near cloud top, whereas in the C-CM cases, mainly the 8–32-μm-sized droplets freeze in updraft regions near the cloud base. Because the initial crystal size is assumed to affect the axis ratio of hexagonal plates, the VF cases produce crystals with larger axis ratios, resulting in smaller mode radii than the C-AC cases. In all cases, irregular polycrystals dominate near cloud top and a band-like structure develops within the cloud, which qualitatively agrees with previous observations. In the VF and C-CM cases, unactivated large droplets arising from coarse-mode aerosol particles contributed significantly to the freezing rate, producing an important influence on crystal habit. Other/Unknown Material Arctic SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Arctic Journal of the Atmospheric Sciences 77 7 2411 2438 |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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ftosti |
language |
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description |
The number concentration of ice particles in Arctic mixed-phase clouds is a major controlling factor of cloud lifetime. The relationships between ice nucleation mode and ice crystal habit development are not yet constrained by observations. This study uses a habit-predicting microphysical scheme within a 3D large-eddy simulation model to evaluate the relationship between immersion freezing and ice habit in a simulated Arctic mixed-phase cloud case. Three immersion freezing parameterizations are considered: a volume-dependent freezing scheme (VF), a parameterization limited to activated droplets (C-AC), and a parameterization limited to coarse aerosol particles (C-CM). Both C-AC and C-CM are based on classical nucleation theory. The freezing rate with VF is found to be greater in downdraft regions than in updraft regions due to the downdraft having a higher number concentration of large droplets. Here, the C-AC cases show active freezing of small droplets near cloud top, whereas in the C-CM cases, mainly the 8–32-μm-sized droplets freeze in updraft regions near the cloud base. Because the initial crystal size is assumed to affect the axis ratio of hexagonal plates, the VF cases produce crystals with larger axis ratios, resulting in smaller mode radii than the C-AC cases. In all cases, irregular polycrystals dominate near cloud top and a band-like structure develops within the cloud, which qualitatively agrees with previous observations. In the VF and C-CM cases, unactivated large droplets arising from coarse-mode aerosol particles contributed significantly to the freezing rate, producing an important influence on crystal habit. |
author |
Hashino, Tempei de Boer, Gijs Okamoto, Hajime Tripoli, Gregory J. |
spellingShingle |
Hashino, Tempei de Boer, Gijs Okamoto, Hajime Tripoli, Gregory J. Relationships between Immersion Freezing and Crystal Habit for Arctic Mixed-Phase Clouds—A Numerical Study |
author_facet |
Hashino, Tempei de Boer, Gijs Okamoto, Hajime Tripoli, Gregory J. |
author_sort |
Hashino, Tempei |
title |
Relationships between Immersion Freezing and Crystal Habit for Arctic Mixed-Phase Clouds—A Numerical Study |
title_short |
Relationships between Immersion Freezing and Crystal Habit for Arctic Mixed-Phase Clouds—A Numerical Study |
title_full |
Relationships between Immersion Freezing and Crystal Habit for Arctic Mixed-Phase Clouds—A Numerical Study |
title_fullStr |
Relationships between Immersion Freezing and Crystal Habit for Arctic Mixed-Phase Clouds—A Numerical Study |
title_full_unstemmed |
Relationships between Immersion Freezing and Crystal Habit for Arctic Mixed-Phase Clouds—A Numerical Study |
title_sort |
relationships between immersion freezing and crystal habit for arctic mixed-phase clouds—a numerical study |
publishDate |
2020 |
url |
http://www.osti.gov/servlets/purl/1673391 https://www.osti.gov/biblio/1673391 https://doi.org/10.1175/jas-d-20-0078.1 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_relation |
http://www.osti.gov/servlets/purl/1673391 https://www.osti.gov/biblio/1673391 https://doi.org/10.1175/jas-d-20-0078.1 doi:10.1175/jas-d-20-0078.1 |
op_doi |
https://doi.org/10.1175/jas-d-20-0078.1 |
container_title |
Journal of the Atmospheric Sciences |
container_volume |
77 |
container_issue |
7 |
container_start_page |
2411 |
op_container_end_page |
2438 |
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1772812051206373376 |