The role of sea ice in thermohaline oscillations
Climate proxy records show the existence of several millennial scale fluctuations during the last glacial period. These abrupt warming (Dansgaard-Oeschger) events were paced by about 1,500 years and also appear to be correlated to episodes of ice surges into the North Atlantic from disintegrating ic...
Main Author: | |
---|---|
Other Authors: | , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
University of North Carolina at Chapel Hill
2011
|
Subjects: | |
Online Access: | https://doi.org/10.17615/j754-5m35 https://cdr.lib.unc.edu/downloads/vt150k608?file=thumbnail https://cdr.lib.unc.edu/downloads/vt150k608 |
id |
ftcarolinadr:cdr.lib.unc.edu:n583xw229 |
---|---|
record_format |
openpolar |
spelling |
ftcarolinadr:cdr.lib.unc.edu:n583xw229 2023-10-09T21:50:59+02:00 The role of sea ice in thermohaline oscillations Saha, Rajarshi College of Arts and Sciences, Department of Physics and Astronomy Jones, Christopher K. R. T. 2011-12 https://doi.org/10.17615/j754-5m35 https://cdr.lib.unc.edu/downloads/vt150k608?file=thumbnail https://cdr.lib.unc.edu/downloads/vt150k608 English eng University of North Carolina at Chapel Hill https://doi.org/10.17615/j754-5m35 https://cdr.lib.unc.edu/downloads/vt150k608?file=thumbnail https://cdr.lib.unc.edu/downloads/vt150k608 http://rightsstatements.org/vocab/InC/1.0/ Dissertation 2011 ftcarolinadr https://doi.org/10.17615/j754-5m35 2023-09-09T22:27:29Z Climate proxy records show the existence of several millennial scale fluctuations during the last glacial period. These abrupt warming (Dansgaard-Oeschger) events were paced by about 1,500 years and also appear to be correlated to episodes of ice surges into the North Atlantic from disintegrating ice sheets. Several model studies have viably demonstrated the ability of abrupt freshwater discharges to trigger fluctuations in the state of the North Atlantic meridional overturning circulation. However, the freshwater hypothesis does not provide a clear answer to the existence of the periodicity. In this study, an idealized model is constructed, which includes the relevant components of the North Atlantic climate system as may be relevant to millennial timescales. These primarily include an overturning pressure driven overturning circulation and thermodynamic sea ice coupled within an idealized geometry representing the ocean basin. Relaxation oscillations are observed at low advective strengths and the periodicity is intrinsically tied to the system's geometry. The physical constraints on sea ice growth in the North Atlantic together with the configuration of the basin, thus impart a characteristic oscillation period. Time varying salinity (freshwater) forcing applied to mimic ice sheet growth and decay phases produce the distinct Bond cycles, as seen in the proxy data. Insolation variations applied to the model also reproduce the fluctuations at about 85,000 years before present. This correlation suggests that the overturning circulation is influenced both by high latitude freshwater anomalies and tropical summer insolation variations, and either trigger can invoke sea ice processes and produce millennial scale oscillations. Doctoral or Postdoctoral Thesis Dansgaard-Oeschger events Ice Sheet North Atlantic Sea ice Carolina Digital Repository (UNC - University of North Carolina) |
institution |
Open Polar |
collection |
Carolina Digital Repository (UNC - University of North Carolina) |
op_collection_id |
ftcarolinadr |
language |
English |
description |
Climate proxy records show the existence of several millennial scale fluctuations during the last glacial period. These abrupt warming (Dansgaard-Oeschger) events were paced by about 1,500 years and also appear to be correlated to episodes of ice surges into the North Atlantic from disintegrating ice sheets. Several model studies have viably demonstrated the ability of abrupt freshwater discharges to trigger fluctuations in the state of the North Atlantic meridional overturning circulation. However, the freshwater hypothesis does not provide a clear answer to the existence of the periodicity. In this study, an idealized model is constructed, which includes the relevant components of the North Atlantic climate system as may be relevant to millennial timescales. These primarily include an overturning pressure driven overturning circulation and thermodynamic sea ice coupled within an idealized geometry representing the ocean basin. Relaxation oscillations are observed at low advective strengths and the periodicity is intrinsically tied to the system's geometry. The physical constraints on sea ice growth in the North Atlantic together with the configuration of the basin, thus impart a characteristic oscillation period. Time varying salinity (freshwater) forcing applied to mimic ice sheet growth and decay phases produce the distinct Bond cycles, as seen in the proxy data. Insolation variations applied to the model also reproduce the fluctuations at about 85,000 years before present. This correlation suggests that the overturning circulation is influenced both by high latitude freshwater anomalies and tropical summer insolation variations, and either trigger can invoke sea ice processes and produce millennial scale oscillations. |
author2 |
College of Arts and Sciences, Department of Physics and Astronomy Jones, Christopher K. R. T. |
format |
Doctoral or Postdoctoral Thesis |
author |
Saha, Rajarshi |
spellingShingle |
Saha, Rajarshi The role of sea ice in thermohaline oscillations |
author_facet |
Saha, Rajarshi |
author_sort |
Saha, Rajarshi |
title |
The role of sea ice in thermohaline oscillations |
title_short |
The role of sea ice in thermohaline oscillations |
title_full |
The role of sea ice in thermohaline oscillations |
title_fullStr |
The role of sea ice in thermohaline oscillations |
title_full_unstemmed |
The role of sea ice in thermohaline oscillations |
title_sort |
role of sea ice in thermohaline oscillations |
publisher |
University of North Carolina at Chapel Hill |
publishDate |
2011 |
url |
https://doi.org/10.17615/j754-5m35 https://cdr.lib.unc.edu/downloads/vt150k608?file=thumbnail https://cdr.lib.unc.edu/downloads/vt150k608 |
genre |
Dansgaard-Oeschger events Ice Sheet North Atlantic Sea ice |
genre_facet |
Dansgaard-Oeschger events Ice Sheet North Atlantic Sea ice |
op_relation |
https://doi.org/10.17615/j754-5m35 https://cdr.lib.unc.edu/downloads/vt150k608?file=thumbnail https://cdr.lib.unc.edu/downloads/vt150k608 |
op_rights |
http://rightsstatements.org/vocab/InC/1.0/ |
op_doi |
https://doi.org/10.17615/j754-5m35 |
_version_ |
1779314080818921472 |