Sensitivity of paleoclimate simulation results to season definitions
International audience According to the Milankovitch theory, slow variations of the Earth's orbital parameters change the amplitude of the seasonal cycle of insolation and are considered to be the main forcing mechanism of glacial-interglacial cycles. Because of the precession and changes in ec...
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ftccsdartic:oai:HAL:hal-03022913v1 2023-05-15T18:18:48+02:00 Sensitivity of paleoclimate simulation results to season definitions Joussaume, Sylvie Braconnot, Pascale Laboratoire de Modélisation du Climat et de l'Environnement (LMCE) 1997 https://hal.archives-ouvertes.fr/hal-03022913 https://hal.archives-ouvertes.fr/hal-03022913/document https://hal.archives-ouvertes.fr/hal-03022913/file/96JD01989.pdf https://doi.org/10.1029/96JD01989 en eng HAL CCSD American Geophysical Union info:eu-repo/semantics/altIdentifier/doi/10.1029/96JD01989 hal-03022913 https://hal.archives-ouvertes.fr/hal-03022913 https://hal.archives-ouvertes.fr/hal-03022913/document https://hal.archives-ouvertes.fr/hal-03022913/file/96JD01989.pdf doi:10.1029/96JD01989 info:eu-repo/semantics/OpenAccess ISSN: 2169-897X EISSN: 2169-8996 Journal of Geophysical Research: Atmospheres https://hal.archives-ouvertes.fr/hal-03022913 Journal of Geophysical Research: Atmospheres, American Geophysical Union, 1997, 102 (D2), pp.1943-1956. ⟨10.1029/96JD01989⟩ [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment info:eu-repo/semantics/article Journal articles 1997 ftccsdartic https://doi.org/10.1029/96JD01989 2021-09-11T22:48:02Z International audience According to the Milankovitch theory, slow variations of the Earth's orbital parameters change the amplitude of the seasonal cycle of insolation and are considered to be the main forcing mechanism of glacial-interglacial cycles. Because of the precession and changes in eccentricity the length of seasons also varies. No absolute phasing is then possible between the insolation curves of two different periods. Various solutions to compare different periods have been given either for astronomical computations [e.g., Berger and Loutre, 1991; Laskar et al., 1993] or for model simulations [e.g., Kutzbach and Otto-Bliesner, 1982; Mitchell et al., 1988], but the sensitivity of model results to the different possible solutions has never been quantified. Our results, based on simulations of the last interglacial climate, 126 kyr B.P., where changes in the length of the seasons are large, clearly show that phase leads or lags between the various solutions used introduce biases in the analysis of insolation and climate change of the same order of magnitude as the Milankovitch forcing. Our main conclusions are that (1) when comparing various model simulations, the date of the vernal equinox (i.e., the phasing of the seasonal cycle of insolation) as well as the definition of seasons must be the same for all models in order to avoid artificial differences; (2) seasons based on astronomical positions are preferred to seasons defined with the same lengths as today, since they better account for the phasing of insolation curves. However, insolation is not the only forcing in most atmospheric general circulation model simulations. We also discuss the impact of the calendar hidden behind the definition of the seasonal cycle of the other boundary conditions, such as sea ice or sea surface temperatures. Article in Journal/Newspaper Sea ice Loutre Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Journal of Geophysical Research: Atmospheres 102 D2 1943 1956 |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment Joussaume, Sylvie Braconnot, Pascale Sensitivity of paleoclimate simulation results to season definitions |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment |
description |
International audience According to the Milankovitch theory, slow variations of the Earth's orbital parameters change the amplitude of the seasonal cycle of insolation and are considered to be the main forcing mechanism of glacial-interglacial cycles. Because of the precession and changes in eccentricity the length of seasons also varies. No absolute phasing is then possible between the insolation curves of two different periods. Various solutions to compare different periods have been given either for astronomical computations [e.g., Berger and Loutre, 1991; Laskar et al., 1993] or for model simulations [e.g., Kutzbach and Otto-Bliesner, 1982; Mitchell et al., 1988], but the sensitivity of model results to the different possible solutions has never been quantified. Our results, based on simulations of the last interglacial climate, 126 kyr B.P., where changes in the length of the seasons are large, clearly show that phase leads or lags between the various solutions used introduce biases in the analysis of insolation and climate change of the same order of magnitude as the Milankovitch forcing. Our main conclusions are that (1) when comparing various model simulations, the date of the vernal equinox (i.e., the phasing of the seasonal cycle of insolation) as well as the definition of seasons must be the same for all models in order to avoid artificial differences; (2) seasons based on astronomical positions are preferred to seasons defined with the same lengths as today, since they better account for the phasing of insolation curves. However, insolation is not the only forcing in most atmospheric general circulation model simulations. We also discuss the impact of the calendar hidden behind the definition of the seasonal cycle of the other boundary conditions, such as sea ice or sea surface temperatures. |
author2 |
Laboratoire de Modélisation du Climat et de l'Environnement (LMCE) |
format |
Article in Journal/Newspaper |
author |
Joussaume, Sylvie Braconnot, Pascale |
author_facet |
Joussaume, Sylvie Braconnot, Pascale |
author_sort |
Joussaume, Sylvie |
title |
Sensitivity of paleoclimate simulation results to season definitions |
title_short |
Sensitivity of paleoclimate simulation results to season definitions |
title_full |
Sensitivity of paleoclimate simulation results to season definitions |
title_fullStr |
Sensitivity of paleoclimate simulation results to season definitions |
title_full_unstemmed |
Sensitivity of paleoclimate simulation results to season definitions |
title_sort |
sensitivity of paleoclimate simulation results to season definitions |
publisher |
HAL CCSD |
publishDate |
1997 |
url |
https://hal.archives-ouvertes.fr/hal-03022913 https://hal.archives-ouvertes.fr/hal-03022913/document https://hal.archives-ouvertes.fr/hal-03022913/file/96JD01989.pdf https://doi.org/10.1029/96JD01989 |
genre |
Sea ice Loutre |
genre_facet |
Sea ice Loutre |
op_source |
ISSN: 2169-897X EISSN: 2169-8996 Journal of Geophysical Research: Atmospheres https://hal.archives-ouvertes.fr/hal-03022913 Journal of Geophysical Research: Atmospheres, American Geophysical Union, 1997, 102 (D2), pp.1943-1956. ⟨10.1029/96JD01989⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/96JD01989 hal-03022913 https://hal.archives-ouvertes.fr/hal-03022913 https://hal.archives-ouvertes.fr/hal-03022913/document https://hal.archives-ouvertes.fr/hal-03022913/file/96JD01989.pdf doi:10.1029/96JD01989 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1029/96JD01989 |
container_title |
Journal of Geophysical Research: Atmospheres |
container_volume |
102 |
container_issue |
D2 |
container_start_page |
1943 |
op_container_end_page |
1956 |
_version_ |
1766195498793828352 |