Amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks
Pleistocene benthic δ 18 O records exhibit strong spectral power at ~41 kyr, indicating that global ice volume has been modulated by Earth's axial tilt. This feature, and weak spectral power in the precessional band, has been attributed to the influence of obliquity on mean annual and seasonal...
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ftdoajarticles:oai:doaj.org/article:8e73fec4f496432b959a6ee869adc15f 2023-05-15T13:15:03+02:00 Amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks S.-Y. Lee C. J. Poulsen 2008-10-01T00:00:00Z https://doaj.org/article/8e73fec4f496432b959a6ee869adc15f EN eng Copernicus Publications http://www.clim-past.net/4/205/2008/cp-4-205-2008.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 https://doaj.org/article/8e73fec4f496432b959a6ee869adc15f Climate of the Past, Vol 4, Iss 4, Pp 205-213 (2008) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2008 ftdoajarticles 2023-01-08T01:34:40Z Pleistocene benthic δ 18 O records exhibit strong spectral power at ~41 kyr, indicating that global ice volume has been modulated by Earth's axial tilt. This feature, and weak spectral power in the precessional band, has been attributed to the influence of obliquity on mean annual and seasonal insolation gradients at high latitudes. In this study, we use a coupled ocean-atmosphere general circulation model to quantify changes in continental snowfall associated with mean annual and seasonal insolation forcing due to a change in obliquity. Our model results indicate that insolation changes associated with a decrease in obliquity amplify continental snowfall in three ways: (1) Local reductions in air temperature enhance precipitation as snowfall. (2) An intensification of the winter meridional insolation gradient strengthens zonal circulation (e.g. the Aleutian low), promoting greater vapor transport from ocean to land and snow precipitation. (3) An increase in the summer meridional insolation gradient enhances summer eddy activity, increasing vapor transport to high-latitude regions. In our experiments, a decrease in obliquity leads to an annual snowfall increase of 25.0 cm; just over one-half of this response (14.1 cm) is attributed to seasonal changes in insolation. Our results indicate that the role of insolation gradients is important in amplifying the relatively weak insolation forcing due to a change in obliquity. Nonetheless, the total snowfall response to obliquity is similar to that due to a shift in Earth's precession, suggesting that obliquity forcing alone can not account for the spectral characteristics of the ice-volume record. Article in Journal/Newspaper aleutian low Directory of Open Access Journals: DOAJ Articles |
institution |
Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
spellingShingle |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 S.-Y. Lee C. J. Poulsen Amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
Pleistocene benthic δ 18 O records exhibit strong spectral power at ~41 kyr, indicating that global ice volume has been modulated by Earth's axial tilt. This feature, and weak spectral power in the precessional band, has been attributed to the influence of obliquity on mean annual and seasonal insolation gradients at high latitudes. In this study, we use a coupled ocean-atmosphere general circulation model to quantify changes in continental snowfall associated with mean annual and seasonal insolation forcing due to a change in obliquity. Our model results indicate that insolation changes associated with a decrease in obliquity amplify continental snowfall in three ways: (1) Local reductions in air temperature enhance precipitation as snowfall. (2) An intensification of the winter meridional insolation gradient strengthens zonal circulation (e.g. the Aleutian low), promoting greater vapor transport from ocean to land and snow precipitation. (3) An increase in the summer meridional insolation gradient enhances summer eddy activity, increasing vapor transport to high-latitude regions. In our experiments, a decrease in obliquity leads to an annual snowfall increase of 25.0 cm; just over one-half of this response (14.1 cm) is attributed to seasonal changes in insolation. Our results indicate that the role of insolation gradients is important in amplifying the relatively weak insolation forcing due to a change in obliquity. Nonetheless, the total snowfall response to obliquity is similar to that due to a shift in Earth's precession, suggesting that obliquity forcing alone can not account for the spectral characteristics of the ice-volume record. |
format |
Article in Journal/Newspaper |
author |
S.-Y. Lee C. J. Poulsen |
author_facet |
S.-Y. Lee C. J. Poulsen |
author_sort |
S.-Y. Lee |
title |
Amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks |
title_short |
Amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks |
title_full |
Amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks |
title_fullStr |
Amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks |
title_full_unstemmed |
Amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks |
title_sort |
amplification of obliquity forcing through mean annual and seasonal atmospheric feedbacks |
publisher |
Copernicus Publications |
publishDate |
2008 |
url |
https://doaj.org/article/8e73fec4f496432b959a6ee869adc15f |
genre |
aleutian low |
genre_facet |
aleutian low |
op_source |
Climate of the Past, Vol 4, Iss 4, Pp 205-213 (2008) |
op_relation |
http://www.clim-past.net/4/205/2008/cp-4-205-2008.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 https://doaj.org/article/8e73fec4f496432b959a6ee869adc15f |
_version_ |
1766266703066431488 |