Stability of the climate system and extreme climates in model experiments
The present thesis examines the ocean and atmospheric dynamics of present-day climate and LGM through Ocean and Atmosphere General Circulation models. Simulating the glacial climate different LGM reconstructions of sea surface temperatures and sea-ice margins are used as forcing fields for the model...
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Universität Bremen
2004
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ftsubbremen:oai:media.suub.uni-bremen.de:Publications/elib/2069 2023-10-01T03:56:41+02:00 Stability of the climate system and extreme climates in model experiments Stabilität des Klimasystems und extreme Klimate in Modellexperimenten Romanova, Vanya Schulz, Michael Lohmann, Gerrit 2004-12-16 application/pdf https://media.suub.uni-bremen.de/handle/elib/2069 https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000011250 eng eng Universität Bremen Fachbereich 05: Geowissenschaften (FB 05) https://media.suub.uni-bremen.de/handle/elib/2069 urn:nbn:de:gbv:46-diss000011250 info:eu-repo/semantics/openAccess Last Glacial Maximum THC stability hysteresis maps glacial atmospheric circulation ice-albedo feedback snowball 550 550 Earth sciences and geology ddc:550 Dissertation doctoralThesis 2004 ftsubbremen 2023-09-03T22:09:40Z The present thesis examines the ocean and atmospheric dynamics of present-day climate and LGM through Ocean and Atmosphere General Circulation models. Simulating the glacial climate different LGM reconstructions of sea surface temperatures and sea-ice margins are used as forcing fields for the models: CLIMAP (1981), a modification of CLIMAP (1981), with additional cooling in the tropics, and reconstructions as produced from Weinelt et al. (1996) and GLAMAP 2000, which show seasonally ice free conditions in the Nordic seas. The stability of the thermohaline circulations under different reconstructions is investigated together with the corresponding atmospheric dynamics. The stability analysis, by means of freshwater flux hysteresis maps reveals mono-stability for each glacial background state, which appears to be a robust feature of the glacial ocean. The impact of the changed orography in North America together with the ice-albedo feedback due to the largely expanded Laurentide Ice Sheet and the reduction of the CO2 concentration are assessed. The results show a strong dependence of the glacial Northern Hemisphere circulation pattern to the changed orography. The Laurentide Ice Sheet forces a deflection of the westerlies, their enhancement and a southward displacement. The oceanic heating contributes only 20-40% to the North Atlantic cooling. Motivated by the extreme climates in the Earth´s history, namely the full earth glaciation in the Neoproterozoic era, known as "snowball" Earth, the atmospheric model is forced with extreme boundary and initial conditions. The impact of land albedo, oceanic heat transport, CO2, initial temperature conditions on the extreme climates are examined. Changing only one boundary or initial condition, the model produces open ice free tropical oceans. Using a proper combination of the varied forcing parameters a full ´Earth glaciation´ results. Oceanic heat transport and orography have only a minor influence on the climate instability. Doctoral or Postdoctoral Thesis Ice Sheet Nordic Seas North Atlantic Sea ice Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) |
institution |
Open Polar |
collection |
Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) |
op_collection_id |
ftsubbremen |
language |
English |
topic |
Last Glacial Maximum THC stability hysteresis maps glacial atmospheric circulation ice-albedo feedback snowball 550 550 Earth sciences and geology ddc:550 |
spellingShingle |
Last Glacial Maximum THC stability hysteresis maps glacial atmospheric circulation ice-albedo feedback snowball 550 550 Earth sciences and geology ddc:550 Romanova, Vanya Stability of the climate system and extreme climates in model experiments |
topic_facet |
Last Glacial Maximum THC stability hysteresis maps glacial atmospheric circulation ice-albedo feedback snowball 550 550 Earth sciences and geology ddc:550 |
description |
The present thesis examines the ocean and atmospheric dynamics of present-day climate and LGM through Ocean and Atmosphere General Circulation models. Simulating the glacial climate different LGM reconstructions of sea surface temperatures and sea-ice margins are used as forcing fields for the models: CLIMAP (1981), a modification of CLIMAP (1981), with additional cooling in the tropics, and reconstructions as produced from Weinelt et al. (1996) and GLAMAP 2000, which show seasonally ice free conditions in the Nordic seas. The stability of the thermohaline circulations under different reconstructions is investigated together with the corresponding atmospheric dynamics. The stability analysis, by means of freshwater flux hysteresis maps reveals mono-stability for each glacial background state, which appears to be a robust feature of the glacial ocean. The impact of the changed orography in North America together with the ice-albedo feedback due to the largely expanded Laurentide Ice Sheet and the reduction of the CO2 concentration are assessed. The results show a strong dependence of the glacial Northern Hemisphere circulation pattern to the changed orography. The Laurentide Ice Sheet forces a deflection of the westerlies, their enhancement and a southward displacement. The oceanic heating contributes only 20-40% to the North Atlantic cooling. Motivated by the extreme climates in the Earth´s history, namely the full earth glaciation in the Neoproterozoic era, known as "snowball" Earth, the atmospheric model is forced with extreme boundary and initial conditions. The impact of land albedo, oceanic heat transport, CO2, initial temperature conditions on the extreme climates are examined. Changing only one boundary or initial condition, the model produces open ice free tropical oceans. Using a proper combination of the varied forcing parameters a full ´Earth glaciation´ results. Oceanic heat transport and orography have only a minor influence on the climate instability. |
author2 |
Schulz, Michael Lohmann, Gerrit |
format |
Doctoral or Postdoctoral Thesis |
author |
Romanova, Vanya |
author_facet |
Romanova, Vanya |
author_sort |
Romanova, Vanya |
title |
Stability of the climate system and extreme climates in model experiments |
title_short |
Stability of the climate system and extreme climates in model experiments |
title_full |
Stability of the climate system and extreme climates in model experiments |
title_fullStr |
Stability of the climate system and extreme climates in model experiments |
title_full_unstemmed |
Stability of the climate system and extreme climates in model experiments |
title_sort |
stability of the climate system and extreme climates in model experiments |
publisher |
Universität Bremen |
publishDate |
2004 |
url |
https://media.suub.uni-bremen.de/handle/elib/2069 https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000011250 |
genre |
Ice Sheet Nordic Seas North Atlantic Sea ice |
genre_facet |
Ice Sheet Nordic Seas North Atlantic Sea ice |
op_relation |
https://media.suub.uni-bremen.de/handle/elib/2069 urn:nbn:de:gbv:46-diss000011250 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1778526757547147264 |