The role of droplet sedimentation in the evolution of low-level clouds over southern West Africa

The role of droplet sedimentation in the evolution of low-level clouds over southern West Africa

<p>Large-eddy simulations are performed to investigate the influence of cloud microphysics on the evolution of low-level clouds that form over southern West Africa during the monsoon season. We find that, even in clouds that are not precipitating, the size of cloud droplets has a non-neglig...

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Main Authors: C. Dearden, A. Hill, H. Coe, T. Choularton
Format: Article
Language:English
Published: Copernicus Publications 2018-10-01
Series:Atmospheric Chemistry and Physics
Online Access:https://www.atmos-chem-phys.net/18/14253/2018/acp-18-14253-2018.pdf
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spelling doaj-47d4abe625a248c482e06ad07c9ae1982020-11-25T01:17:17ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242018-10-0118142531426910.5194/acp-18-14253-2018The role of droplet sedimentation in the evolution of low-level clouds over southern West AfricaC. Dearden0C. Dearden1A. Hill2H. Coe3T. Choularton4Centre for Atmospheric Science, School of Earth and Environmental Science, University of Manchester, Manchester, UKnow at: Centre of Excellence for Modelling the Atmosphere and Climate, School of Earth and Environment, University of Leeds, Leeds, UKMet Office, Exeter, UKCentre for Atmospheric Science, School of Earth and Environmental Science, University of Manchester, Manchester, UKCentre for Atmospheric Science, School of Earth and Environmental Science, University of Manchester, Manchester, UK<p>Large-eddy simulations are performed to investigate the influence of cloud microphysics on the evolution of low-level clouds that form over southern West Africa during the monsoon season. We find that, even in clouds that are not precipitating, the size of cloud droplets has a non-negligible effect on liquid water path. This is explained through the effects of droplet sedimentation, which acts to remove liquid water from the entrainment zone close to cloud top, increasing the liquid water path. Sedimentation also produces a more heterogeneous cloud structure and lowers cloud base height. Our results imply that an appropriate parameterization of the effects of sedimentation is required to improve the representation of the diurnal cycle of the atmospheric boundary layer over southern West Africa in large-scale models.</p>https://www.atmos-chem-phys.net/18/14253/2018/acp-18-14253-2018.pdf
collection DOAJ
language English
format Article
sources DOAJ
author C. Dearden
C. Dearden
A. Hill
H. Coe
T. Choularton
spellingShingle C. Dearden
C. Dearden
A. Hill
H. Coe
T. Choularton
The role of droplet sedimentation in the evolution of low-level clouds over southern West Africa
Atmospheric Chemistry and Physics
author_facet C. Dearden
C. Dearden
A. Hill
H. Coe
T. Choularton
author_sort C. Dearden
title The role of droplet sedimentation in the evolution of low-level clouds over southern West Africa
title_short The role of droplet sedimentation in the evolution of low-level clouds over southern West Africa
title_full The role of droplet sedimentation in the evolution of low-level clouds over southern West Africa
title_fullStr The role of droplet sedimentation in the evolution of low-level clouds over southern West Africa
title_full_unstemmed The role of droplet sedimentation in the evolution of low-level clouds over southern West Africa
title_sort role of droplet sedimentation in the evolution of low-level clouds over southern west africa
publisher Copernicus Publications
series Atmospheric Chemistry and Physics
issn 1680-7316
1680-7324
publishDate 2018-10-01
description <p>Large-eddy simulations are performed to investigate the influence of cloud microphysics on the evolution of low-level clouds that form over southern West Africa during the monsoon season. We find that, even in clouds that are not precipitating, the size of cloud droplets has a non-negligible effect on liquid water path. This is explained through the effects of droplet sedimentation, which acts to remove liquid water from the entrainment zone close to cloud top, increasing the liquid water path. Sedimentation also produces a more heterogeneous cloud structure and lowers cloud base height. Our results imply that an appropriate parameterization of the effects of sedimentation is required to improve the representation of the diurnal cycle of the atmospheric boundary layer over southern West Africa in large-scale models.</p>
url https://www.atmos-chem-phys.net/18/14253/2018/acp-18-14253-2018.pdf
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