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Glacial/interglacial changes in the East Australian current

Journal Article


Abstract


  • The East Australian Current (EAC) is the western boundary current of the south Pacific gyre transporting warm tropical waters to higher southern latitudes. Recent modelling shows that the partial separation of the EAC (∼32°S) and the coupled formation of the Tasman Front (∼34°S) are caused by a steep gradient in the zonally integrated wind stress curl. Analysis of oxygen isotope ratios (δ18 O) in the planktonic foraminifer, Globigerinoides ruber, from sediment cores from the Coral Sea and Tasman Sea indicates that the EAC separation shifted northward to between 23 and 26°S during the last glacial. We suggest these results indicate a significant change in the Pacific wind stress curl during the glacial. Given recent evidence for El Niño-like conditions in the Pacific during the last glacial, with a reduction in the east-west sea surface temperature (SST) gradient, we suggest that weaker trade winds combined with more northerly, stronger westerlies were associated with a change to the wind stress curl, which repositioned the EAC separation and Tasman Front. In contrast, by ∼11 ka BP, the EAC separation was forced south of 26°S. This southward shift was synchronous with a rapid warming of tropical SSTs, and the onset of a La Niña-like SST configuration across the tropical Pacific. It appears that the south Pacific trade winds strengthened accordingly, causing the EAC to readjust its flow. This readjustment of the EAC marks the onset of modern surface-ocean circulation in the southwest Pacific, but the present EAC transport was only achieved in the late Holocene, after 5 ka BP. © Springer-Verlag 2006.

Publication Date


  • 2006

Citation


  • Bostock, H. C., Opdyke, B. N., Gagan, M. K., Kiss, A. E., & Fifield, L. K. (2006). Glacial/interglacial changes in the East Australian current. Climate Dynamics, 26(6), 645-659. doi:10.1007/s00382-005-0103-7

Scopus Eid


  • 2-s2.0-33645303788

Web Of Science Accession Number


Start Page


  • 645

End Page


  • 659

Volume


  • 26

Issue


  • 6

Abstract


  • The East Australian Current (EAC) is the western boundary current of the south Pacific gyre transporting warm tropical waters to higher southern latitudes. Recent modelling shows that the partial separation of the EAC (∼32°S) and the coupled formation of the Tasman Front (∼34°S) are caused by a steep gradient in the zonally integrated wind stress curl. Analysis of oxygen isotope ratios (δ18 O) in the planktonic foraminifer, Globigerinoides ruber, from sediment cores from the Coral Sea and Tasman Sea indicates that the EAC separation shifted northward to between 23 and 26°S during the last glacial. We suggest these results indicate a significant change in the Pacific wind stress curl during the glacial. Given recent evidence for El Niño-like conditions in the Pacific during the last glacial, with a reduction in the east-west sea surface temperature (SST) gradient, we suggest that weaker trade winds combined with more northerly, stronger westerlies were associated with a change to the wind stress curl, which repositioned the EAC separation and Tasman Front. In contrast, by ∼11 ka BP, the EAC separation was forced south of 26°S. This southward shift was synchronous with a rapid warming of tropical SSTs, and the onset of a La Niña-like SST configuration across the tropical Pacific. It appears that the south Pacific trade winds strengthened accordingly, causing the EAC to readjust its flow. This readjustment of the EAC marks the onset of modern surface-ocean circulation in the southwest Pacific, but the present EAC transport was only achieved in the late Holocene, after 5 ka BP. © Springer-Verlag 2006.

Publication Date


  • 2006

Citation


  • Bostock, H. C., Opdyke, B. N., Gagan, M. K., Kiss, A. E., & Fifield, L. K. (2006). Glacial/interglacial changes in the East Australian current. Climate Dynamics, 26(6), 645-659. doi:10.1007/s00382-005-0103-7

Scopus Eid


  • 2-s2.0-33645303788

Web Of Science Accession Number


Start Page


  • 645

End Page


  • 659

Volume


  • 26

Issue


  • 6