Physical processes of cooling and mega-drought during the 4.2 ka BP event: results from TraCE-21ka simulations
It is widely believed that multi-decadal to centennial cooling and drought occurred from 4500 to 3900 BP, known as the 4.2 ka BP event that triggered the collapse of several cultures. However, whether this event was a global event or a regional event and what caused this event remains unclear. In th...
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fttriple:oai:gotriple.eu:4nfRKwMv3OrDQG-OE1m9z 2023-05-15T17:35:24+02:00 Physical processes of cooling and mega-drought during the 4.2 ka BP event: results from TraCE-21ka simulations Yan, Mi Liu, Jian 2019-02-12 https://doi.org/10.5194/cp-15-265-2019 https://cp.copernicus.org/articles/15/265/2019/ en eng Copernicus Publications doi:10.5194/cp-15-265-2019 10670/1.xojgmo 1814-9324 1814-9332 https://cp.copernicus.org/articles/15/265/2019/ undefined Geographica Helvetica - geography eISSN: 1814-9332 geo envir Text https://vocabularies.coar-repositories.org/resource_types/c_18cf/ Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2019 fttriple https://doi.org/10.5194/cp-15-265-2019 2023-01-22T17:39:45Z It is widely believed that multi-decadal to centennial cooling and drought occurred from 4500 to 3900 BP, known as the 4.2 ka BP event that triggered the collapse of several cultures. However, whether this event was a global event or a regional event and what caused this event remains unclear. In this study, we investigated the spatiotemporal characteristics, the possible causes and the related physical processes of the event using a set of long-term climate simulations, including one all-forcing experiment and four single-forcing experiments. The results derived from the all-forcing experiment show that this event occurs over most parts of the Northern Hemisphere (NH), indicating that this event could have been a hemispheric event. The cooler NH and warmer Southern Hemisphere (SH) illustrate that this event could be related to the slowdown of the Atlantic Meridional Overturning Circulation (AMOC). The comparison between the all-forcing experiment and the single-forcing experiments indicates that this event might have been caused by internal variability, while external forcings such as orbital and greenhouse gases might have modulation effects. A positive North Atlantic Oscillation (NAO)-like pattern in the atmosphere (low troposphere) triggered a negative Atlantic Multi-decadal Oscillation (AMO)-like pattern in the ocean, which then triggered a circum-global teleconnection (CGT)-like wave train pattern in the atmosphere (high troposphere). The positive NAO-like pattern and the CGT-like pattern are the direct physical processes that led to the NH cooling and mega-drought. The AMO-like pattern played a “bridge” role in maintaining this barotropic structure in the atmosphere at a multi-decadal–centennial timescale. Our work provides a global image and dynamic background to help better understand the 4.2 ka BP event. Article in Journal/Newspaper North Atlantic North Atlantic oscillation Unknown Climate of the Past 15 1 265 277 |
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geo envir Yan, Mi Liu, Jian Physical processes of cooling and mega-drought during the 4.2 ka BP event: results from TraCE-21ka simulations |
topic_facet |
geo envir |
description |
It is widely believed that multi-decadal to centennial cooling and drought occurred from 4500 to 3900 BP, known as the 4.2 ka BP event that triggered the collapse of several cultures. However, whether this event was a global event or a regional event and what caused this event remains unclear. In this study, we investigated the spatiotemporal characteristics, the possible causes and the related physical processes of the event using a set of long-term climate simulations, including one all-forcing experiment and four single-forcing experiments. The results derived from the all-forcing experiment show that this event occurs over most parts of the Northern Hemisphere (NH), indicating that this event could have been a hemispheric event. The cooler NH and warmer Southern Hemisphere (SH) illustrate that this event could be related to the slowdown of the Atlantic Meridional Overturning Circulation (AMOC). The comparison between the all-forcing experiment and the single-forcing experiments indicates that this event might have been caused by internal variability, while external forcings such as orbital and greenhouse gases might have modulation effects. A positive North Atlantic Oscillation (NAO)-like pattern in the atmosphere (low troposphere) triggered a negative Atlantic Multi-decadal Oscillation (AMO)-like pattern in the ocean, which then triggered a circum-global teleconnection (CGT)-like wave train pattern in the atmosphere (high troposphere). The positive NAO-like pattern and the CGT-like pattern are the direct physical processes that led to the NH cooling and mega-drought. The AMO-like pattern played a “bridge” role in maintaining this barotropic structure in the atmosphere at a multi-decadal–centennial timescale. Our work provides a global image and dynamic background to help better understand the 4.2 ka BP event. |
format |
Article in Journal/Newspaper |
author |
Yan, Mi Liu, Jian |
author_facet |
Yan, Mi Liu, Jian |
author_sort |
Yan, Mi |
title |
Physical processes of cooling and mega-drought during the 4.2 ka BP event: results from TraCE-21ka simulations |
title_short |
Physical processes of cooling and mega-drought during the 4.2 ka BP event: results from TraCE-21ka simulations |
title_full |
Physical processes of cooling and mega-drought during the 4.2 ka BP event: results from TraCE-21ka simulations |
title_fullStr |
Physical processes of cooling and mega-drought during the 4.2 ka BP event: results from TraCE-21ka simulations |
title_full_unstemmed |
Physical processes of cooling and mega-drought during the 4.2 ka BP event: results from TraCE-21ka simulations |
title_sort |
physical processes of cooling and mega-drought during the 4.2 ka bp event: results from trace-21ka simulations |
publisher |
Copernicus Publications |
publishDate |
2019 |
url |
https://doi.org/10.5194/cp-15-265-2019 https://cp.copernicus.org/articles/15/265/2019/ |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_source |
Geographica Helvetica - geography eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-15-265-2019 10670/1.xojgmo 1814-9324 1814-9332 https://cp.copernicus.org/articles/15/265/2019/ |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/cp-15-265-2019 |
container_title |
Climate of the Past |
container_volume |
15 |
container_issue |
1 |
container_start_page |
265 |
op_container_end_page |
277 |
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1766134559467896832 |