Preprints
https://doi.org/10.5194/cp-2021-19
https://doi.org/10.5194/cp-2021-19

  01 Mar 2021

01 Mar 2021

Review status: a revised version of this preprint was accepted for the journal CP and is expected to appear here in due course.

Elucidating modern West Antarctic sea surface conditions: An intercomparison of lipid biomarker proxies, instrumental and numerical-model data

Nele Lamping1, Juliane Müller1,2,3, Jens Hefter1, Gesine Mollenhauer1,2,3, Christian Haas1, Xiaoxu Shi1, Maria-Elena Vorrath1,4, and Gerrit Lohmann1,3,5 Nele Lamping et al.
  • 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Alten Hafen 26, 27568 Bremerhaven, Germany
  • 2Department of Geosciences, University of Bremen, Klagenfurter Straße, 28359 Bremen, Germany
  • 3Marum - Center for Marine Environmental Sciences, Leobener Straße 8, 28359 Bremen, Germany
  • 4Laboratoire des Sciences de l’Environnement Marin (LEMAR), Université de Bretagne Occidentale, Brest, France
  • 5Department of Environmental Physics, University of Bremen, 28359 Bremen, Germany

Abstract. The importance of Southern Ocean sea ice has come into the focus of polar research in the last couple of decades. Especially in West Antarctica, where sea ice has declined, its distribution and evolution play a critical role for the stability of nearby ice shelves. Organic geochemical analyses of marine surface sediments from the West Antarctic continental shelves permit a biomarker-based reconstruction of sea surface conditions in these vulnerable areas. We analysed highly branched isoprenoids (HBIs), such as the sea-ice proxy IPSO25 and phytoplankton-derived HBI-trienes, but also phytosterols and isoprenoidal glycerol dialkyl glycerol tetraethers (GDGTs), which are established tools for the reconstruction of primary productivity and sea surface temperatures, respectively. The combination of IPSO25 with a phytoplankton marker results in the semi-quantitative sea-ice index PIPSO25, which provides useful reconstructions of sea-ice conditions, avoiding misleading over- or underestimations of sea-ice cover. Comparisons of the biomarker-based sea-ice distribution patterns and GDGT-based temperatures with (1) sea-ice distributions obtained from satellite observations and (2) estimated sea-ice patterns and SSTs deduced from modelled data are in reasonable agreement, but also highlight specific aspects that need to be considered when interpreting biomarker data. We further discuss IPSO25 concentrations in the vicinity of ice shelves, where elevated values could be related to the occurrence of ice shelf basal melt water and platelet ice under landfast sea ice.

Nele Lamping et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-19', Anonymous Referee #1, 02 Apr 2021
    • AC1: 'Reply on RC1', Nele Lamping, 22 Jun 2021
  • RC2: 'Comment on cp-2021-19', Anonymous Referee #2, 13 Apr 2021
    • AC2: 'Reply on RC2', Nele Lamping, 22 Jun 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-19', Anonymous Referee #1, 02 Apr 2021
    • AC1: 'Reply on RC1', Nele Lamping, 22 Jun 2021
  • RC2: 'Comment on cp-2021-19', Anonymous Referee #2, 13 Apr 2021
    • AC2: 'Reply on RC2', Nele Lamping, 22 Jun 2021

Nele Lamping et al.

Nele Lamping et al.

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Short summary
We analyzed biomarker concentrations on surface sediment samples from the continental shelves of West Antarctica. Highly branched isoprenoids and GDGTs are used for reconstructing recent sea-ice distribution patterns and ocean temperatures, respectively. We compared our biomarker-based results with data obtained from satellite observations and estimated from a numerical model and find reasonable agreements. Further, a possible link between the sea-ice proxy IPSO25 and platelet ice is discussed.