Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD
Atmospheric circulation modes are important concepts in understanding the variability of atmospheric dynamics. Assuming their spatial patterns to be fixed, such modes are often described by simple indices from rather short observational data sets. The increasing length of reanalysis products allows...
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ftcopernicus:oai:publications.copernicus.org:cp21506 2023-05-15T16:30:04+02:00 Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD Raible, C. C. Lehner, F. González-Rouco, J. F. Fernández-Donado, L. 2018-09-27 application/pdf https://doi.org/10.5194/cp-10-537-2014 https://cp.copernicus.org/articles/10/537/2014/ eng eng doi:10.5194/cp-10-537-2014 https://cp.copernicus.org/articles/10/537/2014/ eISSN: 1814-9332 Text 2018 ftcopernicus https://doi.org/10.5194/cp-10-537-2014 2020-07-20T16:25:10Z Atmospheric circulation modes are important concepts in understanding the variability of atmospheric dynamics. Assuming their spatial patterns to be fixed, such modes are often described by simple indices from rather short observational data sets. The increasing length of reanalysis products allows these concepts and assumptions to be scrutinised. Here we investigate the stability of spatial patterns of Northern Hemisphere teleconnections by using the Twentieth Century Reanalysis as well as several control and transient millennium-scale simulations with coupled models. The observed and simulated centre of action of the two major teleconnection patterns, the North Atlantic Oscillation (NAO) and to some extent the Pacific North American (PNA), are not stable in time. The currently observed dipole pattern of the NAO, its centre of action over Iceland and the Azores, split into a north–south dipole pattern in the western Atlantic with a wave train pattern in the eastern part, connecting the British Isles with West Greenland and the eastern Mediterranean during the period 1940–1969 AD. The PNA centres of action over Canada are shifted southwards and over Florida into the Gulf of Mexico during the period 1915–1944 AD. The analysis further shows that shifts in the centres of action of either teleconnection pattern are not related to changes in the external forcing applied in transient simulations of the last millennium. Such shifts in their centres of action are accompanied by changes in the relation of local precipitation and temperature with the overlying atmospheric mode. These findings further undermine the assumption of stationarity between local climate/proxy variability and large-scale dynamics inherent when using proxy-based reconstructions of atmospheric modes, and call for a more robust understanding of atmospheric variability on decadal timescales. Text Greenland Iceland North Atlantic North Atlantic oscillation Copernicus Publications: E-Journals Canada Greenland Pacific Climate of the Past 10 2 537 550 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Atmospheric circulation modes are important concepts in understanding the variability of atmospheric dynamics. Assuming their spatial patterns to be fixed, such modes are often described by simple indices from rather short observational data sets. The increasing length of reanalysis products allows these concepts and assumptions to be scrutinised. Here we investigate the stability of spatial patterns of Northern Hemisphere teleconnections by using the Twentieth Century Reanalysis as well as several control and transient millennium-scale simulations with coupled models. The observed and simulated centre of action of the two major teleconnection patterns, the North Atlantic Oscillation (NAO) and to some extent the Pacific North American (PNA), are not stable in time. The currently observed dipole pattern of the NAO, its centre of action over Iceland and the Azores, split into a north–south dipole pattern in the western Atlantic with a wave train pattern in the eastern part, connecting the British Isles with West Greenland and the eastern Mediterranean during the period 1940–1969 AD. The PNA centres of action over Canada are shifted southwards and over Florida into the Gulf of Mexico during the period 1915–1944 AD. The analysis further shows that shifts in the centres of action of either teleconnection pattern are not related to changes in the external forcing applied in transient simulations of the last millennium. Such shifts in their centres of action are accompanied by changes in the relation of local precipitation and temperature with the overlying atmospheric mode. These findings further undermine the assumption of stationarity between local climate/proxy variability and large-scale dynamics inherent when using proxy-based reconstructions of atmospheric modes, and call for a more robust understanding of atmospheric variability on decadal timescales. |
format |
Text |
author |
Raible, C. C. Lehner, F. González-Rouco, J. F. Fernández-Donado, L. |
spellingShingle |
Raible, C. C. Lehner, F. González-Rouco, J. F. Fernández-Donado, L. Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD |
author_facet |
Raible, C. C. Lehner, F. González-Rouco, J. F. Fernández-Donado, L. |
author_sort |
Raible, C. C. |
title |
Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD |
title_short |
Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD |
title_full |
Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD |
title_fullStr |
Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD |
title_full_unstemmed |
Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD |
title_sort |
changing correlation structures of the northern hemisphere atmospheric circulation from 1000 to 2100 ad |
publishDate |
2018 |
url |
https://doi.org/10.5194/cp-10-537-2014 https://cp.copernicus.org/articles/10/537/2014/ |
geographic |
Canada Greenland Pacific |
geographic_facet |
Canada Greenland Pacific |
genre |
Greenland Iceland North Atlantic North Atlantic oscillation |
genre_facet |
Greenland Iceland North Atlantic North Atlantic oscillation |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-10-537-2014 https://cp.copernicus.org/articles/10/537/2014/ |
op_doi |
https://doi.org/10.5194/cp-10-537-2014 |
container_title |
Climate of the Past |
container_volume |
10 |
container_issue |
2 |
container_start_page |
537 |
op_container_end_page |
550 |
_version_ |
1766019776531922944 |