Seasonal weather regimes in the North Atlantic region: towards new seasonality?

Abstract. European climate variability is shaped by atmospheric dynamics and local physical processes over the North Atlantic region. As both have strong seasonal features, a better insight of their future seasonality is essential to anticipate changes in weather conditions for human and natural sys...

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Main Authors: Breton, Florentin, Vrac, Mathieu, Yiou, Pascal, Vaittinada Ayar, Pradeebane, Jézéquel, Aglaé
Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA))
Format: Report
Language:English
Published: HAL CCSD 2021
Subjects:
Online Access:https://hal.science/hal-02902945
https://hal.science/hal-02902945/document
https://hal.science/hal-02902945/file/esd-2020-26.pdf
https://doi.org/10.5194/esd-2020-26
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record_format openpolar
spelling ftuniversailles:oai:HAL:hal-02902945v1 2024-04-28T08:29:54+00:00 Seasonal weather regimes in the North Atlantic region: towards new seasonality? Breton, Florentin Vrac, Mathieu Yiou, Pascal Vaittinada Ayar, Pradeebane Jézéquel, Aglaé Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)) Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA) Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR) Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)) 2021-07-08 https://hal.science/hal-02902945 https://hal.science/hal-02902945/document https://hal.science/hal-02902945/file/esd-2020-26.pdf https://doi.org/10.5194/esd-2020-26 en eng HAL CCSD info:eu-repo/semantics/altIdentifier/doi/10.5194/esd-2020-26 hal-02902945 https://hal.science/hal-02902945 https://hal.science/hal-02902945/document https://hal.science/hal-02902945/file/esd-2020-26.pdf doi:10.5194/esd-2020-26 info:eu-repo/semantics/OpenAccess https://hal.science/hal-02902945 2021 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/preprint Preprints, Working Papers, . 2021 ftuniversailles https://doi.org/10.5194/esd-2020-26 2024-04-04T17:32:49Z Abstract. European climate variability is shaped by atmospheric dynamics and local physical processes over the North Atlantic region. As both have strong seasonal features, a better insight of their future seasonality is essential to anticipate changes in weather conditions for human and natural systems. We explore the weather seasonality of the North Atlantic over 1979–2017 and 1979–2100 by using seasonal weather regimes (SWRs) defined by clustering year-round daily fields of geopotential height at 500 hPa (Z500) from the ERA-Interim reanalysis and 12 climate models of the Coupled Model Intercomparison Project fifth phase (CMIP5). The spatial and temporal variability of SWR structures is investigated, as well as associated patterns of surface air temperature. Although the climate models have biases, they reproduce structures and evolutions of SWRs similar to the reanalysis over 1979–2017: decreasing frequency of winter conditions (starting later and ending earlier in the year) and increasing frequency of summer conditions (starting earlier and ending later). These changes are stronger over 1979–2100 than over 1979–2017, associated with a large increase of North Atlantic seasonal mean Z500 and temperature. When using more SWRs (i.e. more freedom in the definition of seasonality), the changes over 1979–2100 correspond to a long-term swap between SWRs, resulting in similar structures (seasonal cycle and weather patterns) with respect to the evolution of the seasonal cycle of Z500 and temperature. To understand whether the evolution of the SWRs is linked to uniform Z500 increase (i.e. uniform warming), or to changes in Z500 spatial patterns (i.e. changes in circulation patterns), we remove the calendar trend in the Z500 regional average to define SWRs based on detrended data (d-SWRs). The temporal properties of d-SWRs appear almost constant, whereas their spatial patterns change. This indicates that the calendar Z500 regional trend drives the evolution of the SWRs and that the changing spatial patterns in d-SWRs ... Report North Atlantic Université de Versailles Saint-Quentin-en-Yvelines: HAL-UVSQ
institution Open Polar
collection Université de Versailles Saint-Quentin-en-Yvelines: HAL-UVSQ
op_collection_id ftuniversailles
language English
topic [SDU.OCEAN]Sciences of the Universe [physics]/Ocean
Atmosphere
spellingShingle [SDU.OCEAN]Sciences of the Universe [physics]/Ocean
Atmosphere
Breton, Florentin
Vrac, Mathieu
Yiou, Pascal
Vaittinada Ayar, Pradeebane
Jézéquel, Aglaé
Seasonal weather regimes in the North Atlantic region: towards new seasonality?
topic_facet [SDU.OCEAN]Sciences of the Universe [physics]/Ocean
Atmosphere
description Abstract. European climate variability is shaped by atmospheric dynamics and local physical processes over the North Atlantic region. As both have strong seasonal features, a better insight of their future seasonality is essential to anticipate changes in weather conditions for human and natural systems. We explore the weather seasonality of the North Atlantic over 1979–2017 and 1979–2100 by using seasonal weather regimes (SWRs) defined by clustering year-round daily fields of geopotential height at 500 hPa (Z500) from the ERA-Interim reanalysis and 12 climate models of the Coupled Model Intercomparison Project fifth phase (CMIP5). The spatial and temporal variability of SWR structures is investigated, as well as associated patterns of surface air temperature. Although the climate models have biases, they reproduce structures and evolutions of SWRs similar to the reanalysis over 1979–2017: decreasing frequency of winter conditions (starting later and ending earlier in the year) and increasing frequency of summer conditions (starting earlier and ending later). These changes are stronger over 1979–2100 than over 1979–2017, associated with a large increase of North Atlantic seasonal mean Z500 and temperature. When using more SWRs (i.e. more freedom in the definition of seasonality), the changes over 1979–2100 correspond to a long-term swap between SWRs, resulting in similar structures (seasonal cycle and weather patterns) with respect to the evolution of the seasonal cycle of Z500 and temperature. To understand whether the evolution of the SWRs is linked to uniform Z500 increase (i.e. uniform warming), or to changes in Z500 spatial patterns (i.e. changes in circulation patterns), we remove the calendar trend in the Z500 regional average to define SWRs based on detrended data (d-SWRs). The temporal properties of d-SWRs appear almost constant, whereas their spatial patterns change. This indicates that the calendar Z500 regional trend drives the evolution of the SWRs and that the changing spatial patterns in d-SWRs ...
author2 Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE)
Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA))
Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR)
Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA))
format Report
author Breton, Florentin
Vrac, Mathieu
Yiou, Pascal
Vaittinada Ayar, Pradeebane
Jézéquel, Aglaé
author_facet Breton, Florentin
Vrac, Mathieu
Yiou, Pascal
Vaittinada Ayar, Pradeebane
Jézéquel, Aglaé
author_sort Breton, Florentin
title Seasonal weather regimes in the North Atlantic region: towards new seasonality?
title_short Seasonal weather regimes in the North Atlantic region: towards new seasonality?
title_full Seasonal weather regimes in the North Atlantic region: towards new seasonality?
title_fullStr Seasonal weather regimes in the North Atlantic region: towards new seasonality?
title_full_unstemmed Seasonal weather regimes in the North Atlantic region: towards new seasonality?
title_sort seasonal weather regimes in the north atlantic region: towards new seasonality?
publisher HAL CCSD
publishDate 2021
url https://hal.science/hal-02902945
https://hal.science/hal-02902945/document
https://hal.science/hal-02902945/file/esd-2020-26.pdf
https://doi.org/10.5194/esd-2020-26
genre North Atlantic
genre_facet North Atlantic
op_source https://hal.science/hal-02902945
2021
op_relation info:eu-repo/semantics/altIdentifier/doi/10.5194/esd-2020-26
hal-02902945
https://hal.science/hal-02902945
https://hal.science/hal-02902945/document
https://hal.science/hal-02902945/file/esd-2020-26.pdf
doi:10.5194/esd-2020-26
op_rights info:eu-repo/semantics/OpenAccess
op_doi https://doi.org/10.5194/esd-2020-26
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