Random and externally controlled occurrences of Dansgaard–Oeschger events
Dansgaard–Oeschger (DO) events constitute the most pronounced mode of centennial to millennial climate variability of the last glacial period. Since their discovery, many decades of research have been devoted to understand the origin and nature of these rapid climate shifts. In recent years, a numbe...
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fttriple:oai:gotriple.eu:oai:doaj.org/article:5ce473b76a004efdb37621aa6cdf090e 2023-05-15T16:00:04+02:00 Random and externally controlled occurrences of Dansgaard–Oeschger events J. Lohmann P. D. Ditlevsen 2018-05-01 https://doi.org/10.5194/cp-14-609-2018 https://www.clim-past.net/14/609/2018/cp-14-609-2018.pdf https://doaj.org/article/5ce473b76a004efdb37621aa6cdf090e en eng Copernicus Publications doi:10.5194/cp-14-609-2018 1814-9324 1814-9332 https://www.clim-past.net/14/609/2018/cp-14-609-2018.pdf https://doaj.org/article/5ce473b76a004efdb37621aa6cdf090e undefined Climate of the Past, Vol 14, Pp 609-617 (2018) envir geo Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2018 fttriple https://doi.org/10.5194/cp-14-609-2018 2023-01-22T19:25:57Z Dansgaard–Oeschger (DO) events constitute the most pronounced mode of centennial to millennial climate variability of the last glacial period. Since their discovery, many decades of research have been devoted to understand the origin and nature of these rapid climate shifts. In recent years, a number of studies have appeared that report emergence of DO-type variability in fully coupled general circulation models via different mechanisms. These mechanisms result in the occurrence of DO events at varying degrees of regularity, ranging from periodic to random. When examining the full sequence of DO events as captured in the North Greenland Ice Core Project (NGRIP) ice core record, one can observe high irregularity in the timing of individual events at any stage within the last glacial period. In addition to the prevailing irregularity, certain properties of the DO event sequence, such as the average event frequency or the relative distribution of cold versus warm periods, appear to be changing throughout the glacial. By using statistical hypothesis tests on simple event models, we investigate whether the observed event sequence may have been generated by stationary random processes or rather was strongly modulated by external factors. We find that the sequence of DO warming events is consistent with a stationary random process, whereas dividing the event sequence into warming and cooling events leads to inconsistency with two independent event processes. As we include external forcing, we find a particularly good fit to the observed DO sequence in a model where the average residence time in warm periods are controlled by global ice volume and cold periods by boreal summer insolation. Article in Journal/Newspaper Dansgaard-Oeschger events Greenland Greenland ice core Greenland Ice core Project ice core NGRIP North Greenland North Greenland Ice Core Project Unknown Greenland Climate of the Past 14 5 609 617 |
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envir geo J. Lohmann P. D. Ditlevsen Random and externally controlled occurrences of Dansgaard–Oeschger events |
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envir geo |
description |
Dansgaard–Oeschger (DO) events constitute the most pronounced mode of centennial to millennial climate variability of the last glacial period. Since their discovery, many decades of research have been devoted to understand the origin and nature of these rapid climate shifts. In recent years, a number of studies have appeared that report emergence of DO-type variability in fully coupled general circulation models via different mechanisms. These mechanisms result in the occurrence of DO events at varying degrees of regularity, ranging from periodic to random. When examining the full sequence of DO events as captured in the North Greenland Ice Core Project (NGRIP) ice core record, one can observe high irregularity in the timing of individual events at any stage within the last glacial period. In addition to the prevailing irregularity, certain properties of the DO event sequence, such as the average event frequency or the relative distribution of cold versus warm periods, appear to be changing throughout the glacial. By using statistical hypothesis tests on simple event models, we investigate whether the observed event sequence may have been generated by stationary random processes or rather was strongly modulated by external factors. We find that the sequence of DO warming events is consistent with a stationary random process, whereas dividing the event sequence into warming and cooling events leads to inconsistency with two independent event processes. As we include external forcing, we find a particularly good fit to the observed DO sequence in a model where the average residence time in warm periods are controlled by global ice volume and cold periods by boreal summer insolation. |
format |
Article in Journal/Newspaper |
author |
J. Lohmann P. D. Ditlevsen |
author_facet |
J. Lohmann P. D. Ditlevsen |
author_sort |
J. Lohmann |
title |
Random and externally controlled occurrences of Dansgaard–Oeschger events |
title_short |
Random and externally controlled occurrences of Dansgaard–Oeschger events |
title_full |
Random and externally controlled occurrences of Dansgaard–Oeschger events |
title_fullStr |
Random and externally controlled occurrences of Dansgaard–Oeschger events |
title_full_unstemmed |
Random and externally controlled occurrences of Dansgaard–Oeschger events |
title_sort |
random and externally controlled occurrences of dansgaard–oeschger events |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/cp-14-609-2018 https://www.clim-past.net/14/609/2018/cp-14-609-2018.pdf https://doaj.org/article/5ce473b76a004efdb37621aa6cdf090e |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Dansgaard-Oeschger events Greenland Greenland ice core Greenland Ice core Project ice core NGRIP North Greenland North Greenland Ice Core Project |
genre_facet |
Dansgaard-Oeschger events Greenland Greenland ice core Greenland Ice core Project ice core NGRIP North Greenland North Greenland Ice Core Project |
op_source |
Climate of the Past, Vol 14, Pp 609-617 (2018) |
op_relation |
doi:10.5194/cp-14-609-2018 1814-9324 1814-9332 https://www.clim-past.net/14/609/2018/cp-14-609-2018.pdf https://doaj.org/article/5ce473b76a004efdb37621aa6cdf090e |
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undefined |
op_doi |
https://doi.org/10.5194/cp-14-609-2018 |
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Climate of the Past |
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14 |
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5 |
container_start_page |
609 |
op_container_end_page |
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