Preprints
https://doi.org/10.5194/cp-2019-52
https://doi.org/10.5194/cp-2019-52

  20 May 2019

20 May 2019

Review status: this preprint was under review for the journal CP. A final paper is not foreseen.

A dynamical reconstruction of the Last Glacial Maximum ocean state constrained by global oxygen isotope data

Charlotte Breitkreuz, André Paul, and Michael Schulz Charlotte Breitkreuz et al.
  • MARUM - Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, Bremen, Germany

Abstract. 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.

This preprint has been withdrawn.

Charlotte Breitkreuz et al.

Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Charlotte Breitkreuz et al.

Charlotte Breitkreuz et al.

Viewed

Total article views: 1,491 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
1,238 212 41 1,491 44 42
  • HTML: 1,238
  • PDF: 212
  • XML: 41
  • Total: 1,491
  • BibTeX: 44
  • EndNote: 42
Views and downloads (calculated since 20 May 2019)
Cumulative views and downloads (calculated since 20 May 2019)

Viewed (geographical distribution)

Total article views: 1,175 (including HTML, PDF, and XML) Thereof 1,152 with geography defined and 23 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Latest update: 12 Apr 2021
Download

This preprint has been withdrawn.

Short summary
We combined a model simulation of the Last Glacial Maximum ocean with sea surface temperature and calcite oxygen isotope data through data assimilation. The reconstructed ocean state is very similar to the modern and it follows that the employed proxy data do not require an ocean state very different from today's. Sensitivity experiments reveal that data from the deep North Atlantic but also from the global deep Southern Ocean are most important to constrain the Atlantic overturning circulation.