A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data
Combining ocean general circulation models with proxy data via data assimilation is a means to obtain estimates of past ocean states that are consistent with model physics as well as with proxy data. The climate during the Last Glacial Maximum (LGM, 19–23 ka) was substantially different from today....
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ftcopernicus:oai:publications.copernicus.org:cpd76113 2023-05-15T13:55:28+02:00 A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data Breitkreuz, Charlotte Paul, André Schulz, Michael 2019-05-20 application/pdf https://doi.org/10.5194/cp-2019-52 https://cp.copernicus.org/preprints/cp-2019-52/ eng eng doi:10.5194/cp-2019-52 https://cp.copernicus.org/preprints/cp-2019-52/ eISSN: 1814-9332 Text 2019 ftcopernicus https://doi.org/10.5194/cp-2019-52 2020-07-20T16:22:50Z Combining ocean general circulation models with proxy data via data assimilation is a means to obtain estimates of past ocean states that are consistent with model physics as well as with proxy data. The climate during the Last Glacial Maximum (LGM, 19–23 ka) was substantially different from today. Even though boundary conditions are comparatively well known, the large-scale patterns of the ocean circulation during this time remain uncertain. Previous efforts to combine ocean models with proxy data have shown dissimilar results regarding the state of the ocean, in particular of the Atlantic Meridional Overturning Circulation. Here, we present a new LGM ocean state estimate that extents previous estimates by using global benthic as well as planktic data on the oxygen isotopic composition of calcite. It is further constrained by global seasonal and annual sea surface temperature (SST) reconstructions. The estimate shows an Atlantic Ocean that is similar to the Late Holocene Atlantic Ocean but with a reduced formation of Antarctic Bottom Water, in contrast to results of previous studies. The results indicate that SST and oxygen isotopic data alone do not require the presence of a shallower North Atlantic Deep Water and a more extensive Antarctic Bottom Water, and highlight the need for more proxy data of different types to obtain reliable ocean state estimates. Additional adjoint sensitivity experiments reveal that data from the deep North Atlantic and from the global deep Southern Ocean are most important to constrain the Atlantic Meridional Overturning Circulation. Text Antarc* Antarctic North Atlantic Deep Water North Atlantic Southern Ocean Copernicus Publications: E-Journals Antarctic Southern Ocean |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Combining ocean general circulation models with proxy data via data assimilation is a means to obtain estimates of past ocean states that are consistent with model physics as well as with proxy data. The climate during the Last Glacial Maximum (LGM, 19–23 ka) was substantially different from today. Even though boundary conditions are comparatively well known, the large-scale patterns of the ocean circulation during this time remain uncertain. Previous efforts to combine ocean models with proxy data have shown dissimilar results regarding the state of the ocean, in particular of the Atlantic Meridional Overturning Circulation. Here, we present a new LGM ocean state estimate that extents previous estimates by using global benthic as well as planktic data on the oxygen isotopic composition of calcite. It is further constrained by global seasonal and annual sea surface temperature (SST) reconstructions. The estimate shows an Atlantic Ocean that is similar to the Late Holocene Atlantic Ocean but with a reduced formation of Antarctic Bottom Water, in contrast to results of previous studies. The results indicate that SST and oxygen isotopic data alone do not require the presence of a shallower North Atlantic Deep Water and a more extensive Antarctic Bottom Water, and highlight the need for more proxy data of different types to obtain reliable ocean state estimates. Additional adjoint sensitivity experiments reveal that data from the deep North Atlantic and from the global deep Southern Ocean are most important to constrain the Atlantic Meridional Overturning Circulation. |
format |
Text |
author |
Breitkreuz, Charlotte Paul, André Schulz, Michael |
spellingShingle |
Breitkreuz, Charlotte Paul, André Schulz, Michael A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data |
author_facet |
Breitkreuz, Charlotte Paul, André Schulz, Michael |
author_sort |
Breitkreuz, Charlotte |
title |
A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data |
title_short |
A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data |
title_full |
A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data |
title_fullStr |
A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data |
title_full_unstemmed |
A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data |
title_sort |
dynamical reconstruction of the last glacial maximum ocean state constrained by global oxygen isotope data |
publishDate |
2019 |
url |
https://doi.org/10.5194/cp-2019-52 https://cp.copernicus.org/preprints/cp-2019-52/ |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic North Atlantic Deep Water North Atlantic Southern Ocean |
genre_facet |
Antarc* Antarctic North Atlantic Deep Water North Atlantic Southern Ocean |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-2019-52 https://cp.copernicus.org/preprints/cp-2019-52/ |
op_doi |
https://doi.org/10.5194/cp-2019-52 |
_version_ |
1766262114025996288 |