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Optimized coral reconstructions of the Indian Ocean Dipole: an assessment of location and length considerations

Citation

Abram, NJ and Dixon, BC and Rosevear, MG and Plunkett, B and Gagan, MK and Hantoro, WS and Phipps, SJ, Optimized coral reconstructions of the Indian Ocean Dipole: an assessment of location and length considerations, Paleoceanography, 30, (10) pp. 1391-1405. ISSN 0883-8305 (2015) [Refereed Article]


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Copyright Statement

Copyright 2015 American Geophysical Union

DOI: doi:10.1002/2015PA002810

Abstract

The Indian Ocean Dipole (IOD; or Indian Ocean Zonal Mode) is a coupled ocean-atmosphere climate oscillation that has profound impacts on rainfall distribution across the Indian Ocean region. Instrumental records provide a reliable representation of IOD behavior since 1958, while coral reconstructions currently extend the IOD history back to 1846. Large fluctuations in the number and intensity of positive IOD events over time are evident in these records, but it is unclear to what extent this represents multidecadal modulation of the IOD or an anthropogenically forced change in IOD behavior. In this study we explore the suitability of coral records from single-site locations in the equatorial Indian Ocean for capturing information about the occurrence and magnitude of positive IOD (pIOD) events. We find that the optimum location for coral reconstructions of the IOD occurs in the southeastern equatorial Indian Ocean, along the coast of Java and Sumatra between ~3 and 7S. Here the strong ocean cooling and atmospheric drying during pIOD events are unambiguously recorded in coral oxygen isotope records, which capture up to 50% of IOD variance. Unforced experiments with coupled climate models suggest that potential biases in coral estimates of pIOD frequency are skewed toward overestimating pIOD recurrence intervals and become larger with shorter reconstruction windows and longer pIOD recurrence times. Model output also supports the assumption of stationarity in sea surface temperature relationships in the optimum IOD location that is necessary for paleoclimate reconstructions. This study provides a targeted framework for the future generation of paleoclimate records, including optimized coral reconstructions of past IOD variability.

Item Details

Item Type:Refereed Article
Keywords:palaeoclimate, Indian Ocean Dipole, corals, isotopes
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Palaeoclimatology
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate Variability (excl. Social Impacts)
Author:Phipps, SJ (Dr Steven Phipps)
ID Code:104741
Year Published:2015
Deposited By:IMAS Research and Education Centre
Deposited On:2015-11-18
Last Modified:2017-10-30
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