Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps
We examine the impact of horizontal resolution and model time step on the climate of the OpenIFS version 43r3 atmospheric general circulation model. A series of simulations for the period 1979–2019 are conducted with various horizontal resolutions (i.e. ∼100 , ∼50 , and ∼25 km) while maintaining the...
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ftdoajarticles:oai:doaj.org/article:282b98106f9c4d1abbda32ca55812a5f 2024-09-15T18:37:23+00:00 Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps A. Savita J. Kjellsson R. Pilch Kedzierski M. Latif T. Rahm S. Wahl W. Park 2024-02-01T00:00:00Z https://doi.org/10.5194/gmd-17-1813-2024 https://doaj.org/article/282b98106f9c4d1abbda32ca55812a5f EN eng Copernicus Publications https://gmd.copernicus.org/articles/17/1813/2024/gmd-17-1813-2024.pdf https://doaj.org/toc/1991-959X https://doaj.org/toc/1991-9603 doi:10.5194/gmd-17-1813-2024 1991-959X 1991-9603 https://doaj.org/article/282b98106f9c4d1abbda32ca55812a5f Geoscientific Model Development, Vol 17, Pp 1813-1829 (2024) Geology QE1-996.5 article 2024 ftdoajarticles https://doi.org/10.5194/gmd-17-1813-2024 2024-08-05T17:49:56Z We examine the impact of horizontal resolution and model time step on the climate of the OpenIFS version 43r3 atmospheric general circulation model. A series of simulations for the period 1979–2019 are conducted with various horizontal resolutions (i.e. ∼100 , ∼50 , and ∼25 km) while maintaining the same time step (i.e. 15 min) and using different time steps (i.e. 60, 30, and 15 min) at 100 km horizontal resolution. We find that the surface zonal wind bias is significantly reduced over certain regions such as the Southern Ocean and the Northern Hemisphere mid-latitudes and in tropical and subtropical regions at a high horizontal resolution (i.e. ∼25 km). Similar improvement is evident too when using a coarse-resolution model ( ∼100 km) with a smaller time step (i.e. 30 and 15 min). We also find improvements in Rossby wave amplitude and phase speed, as well as in weather regime patterns, when a smaller time step or higher horizontal resolution is used. The improvement in the wind bias when using the shorter time step is mostly due to an increase in shallow and mid-level convection that enhances vertical mixing in the lower troposphere. The enhanced mixing allows frictional effects to influence a deeper layer and reduces wind and wind speed throughout the troposphere. However, precipitation biases generally increase with higher horizontal resolutions or smaller time steps, whereas the surface air temperature bias exhibits a small improvement over North America and the eastern Eurasian continent. We argue that the bias improvement in the highest-horizontal-resolution (i.e. ∼25 km) configuration benefits from a combination of both the enhanced horizontal resolution and the shorter time step. In summary, we demonstrate that, by reducing the time step in the coarse-resolution ( ∼100 km) OpenIFS model, one can alleviate some climate biases at a lower cost than by increasing the horizontal resolution. Article in Journal/Newspaper Southern Ocean Directory of Open Access Journals: DOAJ Articles Geoscientific Model Development 17 4 1813 1829 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geology QE1-996.5 |
spellingShingle |
Geology QE1-996.5 A. Savita J. Kjellsson R. Pilch Kedzierski M. Latif T. Rahm S. Wahl W. Park Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps |
topic_facet |
Geology QE1-996.5 |
description |
We examine the impact of horizontal resolution and model time step on the climate of the OpenIFS version 43r3 atmospheric general circulation model. A series of simulations for the period 1979–2019 are conducted with various horizontal resolutions (i.e. ∼100 , ∼50 , and ∼25 km) while maintaining the same time step (i.e. 15 min) and using different time steps (i.e. 60, 30, and 15 min) at 100 km horizontal resolution. We find that the surface zonal wind bias is significantly reduced over certain regions such as the Southern Ocean and the Northern Hemisphere mid-latitudes and in tropical and subtropical regions at a high horizontal resolution (i.e. ∼25 km). Similar improvement is evident too when using a coarse-resolution model ( ∼100 km) with a smaller time step (i.e. 30 and 15 min). We also find improvements in Rossby wave amplitude and phase speed, as well as in weather regime patterns, when a smaller time step or higher horizontal resolution is used. The improvement in the wind bias when using the shorter time step is mostly due to an increase in shallow and mid-level convection that enhances vertical mixing in the lower troposphere. The enhanced mixing allows frictional effects to influence a deeper layer and reduces wind and wind speed throughout the troposphere. However, precipitation biases generally increase with higher horizontal resolutions or smaller time steps, whereas the surface air temperature bias exhibits a small improvement over North America and the eastern Eurasian continent. We argue that the bias improvement in the highest-horizontal-resolution (i.e. ∼25 km) configuration benefits from a combination of both the enhanced horizontal resolution and the shorter time step. In summary, we demonstrate that, by reducing the time step in the coarse-resolution ( ∼100 km) OpenIFS model, one can alleviate some climate biases at a lower cost than by increasing the horizontal resolution. |
format |
Article in Journal/Newspaper |
author |
A. Savita J. Kjellsson R. Pilch Kedzierski M. Latif T. Rahm S. Wahl W. Park |
author_facet |
A. Savita J. Kjellsson R. Pilch Kedzierski M. Latif T. Rahm S. Wahl W. Park |
author_sort |
A. Savita |
title |
Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps |
title_short |
Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps |
title_full |
Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps |
title_fullStr |
Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps |
title_full_unstemmed |
Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps |
title_sort |
assessment of climate biases in openifs version 43r3 across model horizontal resolutions and time steps |
publisher |
Copernicus Publications |
publishDate |
2024 |
url |
https://doi.org/10.5194/gmd-17-1813-2024 https://doaj.org/article/282b98106f9c4d1abbda32ca55812a5f |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Geoscientific Model Development, Vol 17, Pp 1813-1829 (2024) |
op_relation |
https://gmd.copernicus.org/articles/17/1813/2024/gmd-17-1813-2024.pdf https://doaj.org/toc/1991-959X https://doaj.org/toc/1991-9603 doi:10.5194/gmd-17-1813-2024 1991-959X 1991-9603 https://doaj.org/article/282b98106f9c4d1abbda32ca55812a5f |
op_doi |
https://doi.org/10.5194/gmd-17-1813-2024 |
container_title |
Geoscientific Model Development |
container_volume |
17 |
container_issue |
4 |
container_start_page |
1813 |
op_container_end_page |
1829 |
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1810481743525838848 |