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Miltenberger, AK, Field, PR, Hill, AA et al. (5 more authors) (2018) Aerosol-cloud interactions in mixed-phase convective clouds - Part 1: Aerosol perturbations. Atmospheric Chemistry and Physics, 18 (5). pp. 3119-3145. ISSN 1680-7316
Abstract
Changes induced by perturbed aerosol conditions in moderately deep mixed-phase convective clouds (cloud top height 5 km) developing along sea-breeze convergence lines are investigated with high-resolution numerical model simulations. The simulations utilise the newly developed Cloud-AeroSol Interacting Microphysics (CASIM) module for the Unified Model (UM), which allows for the representation of the two-way interaction between cloud and aerosol fields. Simulations are evaluated against observations collected during the COnvective Precipitation Experiment (COPE) field campaign over the southwestern peninsula of the UK in 2013. The simulations compare favourably with observed thermodynamic profiles, cloud base cloud droplet number concentrations (CDNC), cloud depth, and radar reflectivity statistics. Including the modification of aerosol fields by cloud microphysical processes improves the correspondence with observed CDNC values and spatial variability, but reduces the agreement with observations for average cloud size and cloud top height. < br > < br > Accumulated precipitation is suppressed for higher-aerosol conditions before clouds become organised along the sea-breeze convergence lines. Changes in precipitation are smaller in simulations with aerosol processing. The precipitation suppression is due to less efficient precipitation production by warm-phase microphysics, consistent with parcel model predictions. < br > < br > In contrast, after convective cells organise along the sea-breeze convergence zone, accumulated precipitation increases with aerosol concentrations. Condensate production increases with the aerosol concentrations due to higher vertical velocities in the convective cores and higher cloud top heights. However, for the highest-aerosol scenarios, no further increase in the condensate production occurs, as clouds grow into an upper-level stable layer. In these cases, the reduced precipitation efficiency (PE) dominates the precipitation response and no further precipitation enhancement occurs. Previous studies of deep convective clouds have related larger vertical velocities under high-aerosol conditions to enhanced latent heating from freezing. In the presented simulations changes in latent heating above the 0°C are negligible, but latent heating from condensation increases with aerosol concentrations. It is hypothesised that this increase is related to changes in the cloud field structure reducing the mixing of environmental air into the convective core. < br > < br > The precipitation response of the deeper mixed-phase clouds along well-established convergence lines can be the opposite of predictions from parcel models. This occurs when clouds interact with a pre-existing thermodynamic environment and cloud field structural changes occur that are not captured by simple parcel model approaches.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) 2018, Author(s). This work is distributed under the Creative Commons Attribution 4.0 License. This licence does not affect the Crown copyright work, which is reusable under the Open Government Licence (OGL). The Creative Commons Attribution 4.0 License and the OGL are interoperable and do not conflict with, reduce, or limit each other. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > National Centre for Atmos Science (NCAS) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 22 Mar 2018 09:54 |
Last Modified: | 27 Mar 2018 15:15 |
Status: | Published |
Publisher: | European Geosciences Union |
Identification Number: | 10.5194/acp-18-3119-2018 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:128871 |
Available Versions of this Item
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Aerosol-cloud interactions in mixed-phase convective clouds. Part 1: Aerosol perturbations. (deposited 25 Sep 2018 09:20)
- Aerosol-cloud interactions in mixed-phase convective clouds - Part 1: Aerosol perturbations. (deposited 22 Mar 2018 09:54) [Currently Displayed]