Variations in Western Pacific Warm Pool surface and thermocline conditions over the past 110,000 years: Forcing mechanisms and implications for the glacial Walker circulation - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Quaternary Science Reviews Année : 2018

Variations in Western Pacific Warm Pool surface and thermocline conditions over the past 110,000 years: Forcing mechanisms and implications for the glacial Walker circulation

Martina Hollstein
  • Fonction : Auteur
Mahyar Mohtadi
  • Fonction : Auteur
Yair Rosenthal
  • Fonction : Auteur
Matthias Prange
  • Fonction : Auteur
Delia W Oppo
  • Fonction : Auteur
Gema Martínez Méndez
  • Fonction : Auteur
Paola Moffa Sanchez
  • Fonction : Auteur
Stephan Steinke
  • Fonction : Auteur
Dierk Hebbeln
  • Fonction : Auteur

Résumé

Surface and thermocline conditions of the Western Pacific Warm Pool (WPWP) reflect changes in regional and basin scale ocean and atmosphere circulations and in turn may affect climate globally. Previous studies suggest that a range of factors influences the WPWP on different timescales, however the precise forcings and mechanisms are unclear. Combining surface and thermocline records from sediment cores offshore Papua New Guinea we explore the influence of local and remote processes on the WPWP in response to astronomical forcing and changing glacial-interglacial boundary conditions over the past 110 kyr. We find that thermocline temperatures change with variations in Earth's obliquity with higher temperatures coinciding with high obliquity, which is attributed to variations in subduction and advection of the South Pacific Tropical Water. In contrast, rainfall variations associated with meridional migrations of the Intertropical Convergence Zone are primarily driven by changes in insolation due to precession. Records of bulk sedimentary Ti/Ca and foraminiferal Nd/Ca indicate an additional influence of obliquity, which, however, cannot unambiguously be related to changes in precipitation. Finally, our results suggest a thermocline deepening during the Last Glacial Maximum (LGM). A compilation of available proxy records illustrates a dipole-like pattern of LGM thermocline depth anomalies with a shoaling (deepening) in the northern (southern) WPWP. A comparison of the proxy compilation with an ensemble of Paleoclimate Model Intercomparison Project (PMIP) climate model simulations reveals that the spatial pattern of LGM thermocline depth anomalies is mainly attributable to a contraction of the Pacific Walker circulation on its western side.

Dates et versions

hal-02091063 , version 1 (05-04-2019)

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Citer

Martina Hollstein, Mahyar Mohtadi, Yair Rosenthal, Matthias Prange, Delia W Oppo, et al.. Variations in Western Pacific Warm Pool surface and thermocline conditions over the past 110,000 years: Forcing mechanisms and implications for the glacial Walker circulation. Quaternary Science Reviews, 2018, 201, pp.429-445. ⟨10.1016/j.quascirev.2018.10.030⟩. ⟨hal-02091063⟩
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