Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2017-109
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
25 Sep 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
Assessing the impact of large volcanic eruptions of the Last Millennium on Australian rainfall regimes
Stephanie Blake1,2, Sophie C. Lewis2,3, and Allegra N. LeGrande4 1Climate Change Research Centre, University of New South Wales, Sydney, UNSW, Australia
2ARC Centre of Excellence for Climate System Science
3Fenner School of Environment and Society, The Australian National University, Canberra, ACT, Australia
4NASA Goddard Institute for Space Studies and Center for Climate Systems Research, Columbia University
Abstract. Explosive volcanism is an important natural climate forcing, impacting global surface temperatures and regional precipitation. Although previous studies have investigated aspects of the impact of tropical volcanism on various ocean-atmosphere systems and regional climate regimes, volcanic eruptions remain a poorly understood climate forcing and climatic responses are not well constrained. In this study, volcanic eruptions are explored in particular reference to Australian precipitation, and both the Indian Ocean Dipole (IOD) and El Nino-Southern Oscillation (ENSO). Using nine realisations of the Last Millennium (LM) with different time-evolving forcing combinations, from the NASA GISS ModelE2-R, the impact of the 6 largest tropical volcanic eruptions of this period are investigated. Overall, we find that volcanic aerosol forcing increased the likelihood of El Nino and positive IOD conditions for up to four years following an eruption, and resulted in positive precipitation anomalies over northwest (NW) and southeast (SE) Australia. Larger atmospheric sulfate loading coincides with more persistent positive IOD and El Nino conditions, enhanced positive precipitation anomalies over NW Australia, and dampened precipitation anomalies over SE Australia.

Citation: Blake, S., Lewis, S. C., and LeGrande, A. N.: Assessing the impact of large volcanic eruptions of the Last Millennium on Australian rainfall regimes, Clim. Past Discuss., https://doi.org/10.5194/cp-2017-109, in review, 2017.
Stephanie Blake et al.
Stephanie Blake et al.
Stephanie Blake et al.

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Short summary
We studied the impact of the six largest tropical eruptions in reference to Australian precipitation, the Indian Ocean Dipole (IOD) and El Nino-Southern Oscillation (ENSO). Volcanic forcing increased the likelihood of El Nino's and positive IOD's (pIOD), and caused positive rainfall anomalies over northwest (NW) and southeast (SE) Australia. Larger sulfate loading caused more persistent pIOD and El Ninos, enhanced precipitation over NW Australia, and dampened precipitation over SE Australia.
We studied the impact of the six largest tropical eruptions in reference to Australian...
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