Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model
Aerosol particles influence cloud formation and properties. Hence climate models that aim for a physical representation of the climate system include aerosol modules. In order to represent more and more processes and aerosol species, their representation has grown increasingly detailed. However, dep...
Main Authors: | , , |
---|---|
Format: | Text |
Language: | English |
Published: |
2024
|
Subjects: | |
Online Access: | https://doi.org/10.5194/egusphere-2023-2783 https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2783/ |
id |
ftcopernicus:oai:publications.copernicus.org:egusphere116157 |
---|---|
record_format |
openpolar |
spelling |
ftcopernicus:oai:publications.copernicus.org:egusphere116157 2024-06-23T07:56:56+00:00 Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model Proske, Ulrike Ferrachat, Sylvaine Lohmann, Ulrike 2024-05-23 application/pdf https://doi.org/10.5194/egusphere-2023-2783 https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2783/ eng eng doi:10.5194/egusphere-2023-2783 https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2783/ eISSN: Text 2024 ftcopernicus https://doi.org/10.5194/egusphere-2023-2783 2024-06-13T01:23:50Z Aerosol particles influence cloud formation and properties. Hence climate models that aim for a physical representation of the climate system include aerosol modules. In order to represent more and more processes and aerosol species, their representation has grown increasingly detailed. However, depending on one's modelling purpose, the increased model complexity may not be beneficial, for example because it hinders understanding of model behaviour. Hence we develop a simplification in the form of a climatology of aerosol concentrations. In one approach, the climatology prescribes properties important for cloud droplet and ice crystal formation, the gateways for aerosols to enter the model cloud microphysics scheme. Another approach prescribes aerosol mass and number concentrations in general. Both climatologies are derived from full ECHAM-HAM simulations and can serve to replace the HAM aerosol module and thus drastically simplify the aerosol treatment. The first simplification reduces computational model time by roughly 65 %. However, the naive mean climatological treatment needs improvement to give results that are satisfyingly close to the full model. We find that mean cloud condensation nuclei (CCN) concentrations yield an underestimation of cloud droplet number concentration (CDNC) in the Southern Ocean, which we can reduce by allowing only CCN at cloud base (which have experienced hygroscopic growth in these conditions) to enter the climatology. This highlights the value of the simplification approach in pointing to unexpected model behaviour and providing a new perspective for its study and model development. Text Southern Ocean Copernicus Publications: E-Journals Southern Ocean |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Aerosol particles influence cloud formation and properties. Hence climate models that aim for a physical representation of the climate system include aerosol modules. In order to represent more and more processes and aerosol species, their representation has grown increasingly detailed. However, depending on one's modelling purpose, the increased model complexity may not be beneficial, for example because it hinders understanding of model behaviour. Hence we develop a simplification in the form of a climatology of aerosol concentrations. In one approach, the climatology prescribes properties important for cloud droplet and ice crystal formation, the gateways for aerosols to enter the model cloud microphysics scheme. Another approach prescribes aerosol mass and number concentrations in general. Both climatologies are derived from full ECHAM-HAM simulations and can serve to replace the HAM aerosol module and thus drastically simplify the aerosol treatment. The first simplification reduces computational model time by roughly 65 %. However, the naive mean climatological treatment needs improvement to give results that are satisfyingly close to the full model. We find that mean cloud condensation nuclei (CCN) concentrations yield an underestimation of cloud droplet number concentration (CDNC) in the Southern Ocean, which we can reduce by allowing only CCN at cloud base (which have experienced hygroscopic growth in these conditions) to enter the climatology. This highlights the value of the simplification approach in pointing to unexpected model behaviour and providing a new perspective for its study and model development. |
format |
Text |
author |
Proske, Ulrike Ferrachat, Sylvaine Lohmann, Ulrike |
spellingShingle |
Proske, Ulrike Ferrachat, Sylvaine Lohmann, Ulrike Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model |
author_facet |
Proske, Ulrike Ferrachat, Sylvaine Lohmann, Ulrike |
author_sort |
Proske, Ulrike |
title |
Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model |
title_short |
Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model |
title_full |
Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model |
title_fullStr |
Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model |
title_full_unstemmed |
Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model |
title_sort |
developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model |
publishDate |
2024 |
url |
https://doi.org/10.5194/egusphere-2023-2783 https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2783/ |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
eISSN: |
op_relation |
doi:10.5194/egusphere-2023-2783 https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2783/ |
op_doi |
https://doi.org/10.5194/egusphere-2023-2783 |
_version_ |
1802650336698040320 |