Indian Ocean Dipole Overrides ENSO’s Influence on Cool Season Rainfall across the Eastern Seaboard of Australia

Pepler, Acacia; Timbal, Bertrand; Rakich, Clinton S.; Coutts-Smith, Aaron

doi:10.1175/jcli-d-13-00554.1

Cited by 55 publications

(68 citation statements)

References 24 publications

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“…11) in the CR ensemble mean, and in years 0 and 2 in the 2 × G ensemble mean. This could be due to the positive precipitation anomalies that can be generated by combined El Niño and pIOD events in the NW Australian region (Meyers et al, 2007;Pepler et al, 2014), which enhance the precipitation surplus caused by volcanic aerosols.…”

Section: Discussionmentioning

confidence: 99%

“…Preconditioning does impact the severity of the ENSO response. Predybaylo et al (2017) found that years with an initial central Pacific ENSO phase show the largest statistical impact from Pinatubo-sized eruptions, and that summer eruptions coincided with a more pronounced El Niño response.…”

Section: Introductionmentioning

confidence: 91%

“…El Niño events typically cause averaged precipitation deficits, while La Niña events cause positive precipitation anomalies (Meyers et al, 2007;Pepler et al, 2014). In addition, a statistical relationship has been demonstrated between explosive tropical volcanism and ENSO where large tropical eruptions can increase the likelihood and amplitude of an El Niño event in following years, followed by a weaker La Niña state (Adams et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Robock (2000) argued that both El Chichon and Pinatubo reached their peak forcing after the initiation of El Niño events, indicating a coincidental relationship. Other studies (Driscoll et al, 2012;Lewis and Karoly, 2014;Lewis and LeGrande, 2015;Predybaylo et al, 2017) have, however, pointed out challenges in determining long-term characteristics of ENSO due to short instrumental records. It is also difficult to determine its relationship to volcanic forcing owing to variable representations of both ENSO and volcanic aerosols in GCMs (global climate models).…”

Section: Introductionmentioning

confidence: 99%

“…The IOD is the zonal sea surface temperature (SST) gradient between the tropical western Indian Ocean (WIO) and the tropical south eastern Indian Ocean (EIO) (Roxy et al, 2011), defined by the dipole mode index (DMI). Positive IOD (pIOD) states typically cause averaged precipitation deficits over Australia, and negative IOD (nIOD) states cause a surplus (Meyers et al, 2007;Pepler et al, 2014). While ENSO is often considered primarily responsible for triggering Australian droughts, the IOD has been shown to have an equal, if not larger, impact on heavily populated areas of Australia; all significant southeastern Australian droughts during the 20th century have shown a larger response to pIOD events than El Niño events (Ummenhofer et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Assessing the impact of large volcanic eruptions of the last millennium (850–1850 CE) on Australian rainfall regimes

et al. 2018

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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 Niño-Southern Oscillation (ENSO). Using nine realisations of the last millennium (LM) (850-1850 CE) with different time-evolving forcing combinations, from the NASA GISS ModelE2-R, the impact of the six largest tropical volcanic eruptions of this period are investigated. Overall, we find that volcanic aerosol forcing increased the likelihood of El Niño and positive IOD conditions for up to four years following an eruption, and resulted in positive precipitation anomalies over north-west (NW) and south-east (SE) Australia. Larger atmospheric sulfate loading during larger volcanic eruptions coincided with more persistent positive IOD and El Niño conditions, enhanced positive precipitation anomalies over NW Australia, and dampened precipitation anomalies over SE Australia.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessing the impact of large volcanic eruptions of the last millennium (850–1850 CE) on Australian rainfall regimes

et al. 2018

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The influence of topography on midlatitude cyclones on Australia's east coast

et al. 2017

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The east coast of Australia has a relatively high frequency of midlatitude cyclones, locally known as East Coast Lows (ECLs), which can cause severe weather including widespread flooding and coastal erosion. The elevated topography close to the east coast has been hypothesized to play a role in both the genesis and impacts of cyclones in this region, but existing studies have been limited to case studies of individual events. In this paper we present the results from two 20 year simulations over the Australian region using the Weather Research and Forecasting Model and assess the results from removing all topography in the region on both mean atmospheric circulation and ECL frequency. Removing topography results in an increase in sea level pressure to the south of Australia and an increase in moisture flux convergence and rainfall near the east coast, as well as a decrease in potential vorticity to the north of the ECL region. This results in a change in the spatial distribution of cyclones, with a 37% decrease in the frequency of cyclones that develop to the south of the ECL region but a 20% increase in cyclones near the east coast. This results in little overall change in the frequency of ECLs and suggests that coarse topography is unlikely to be responsible for the difficulties in simulating coastal cyclones in global climate models.

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Correlations Between Extreme Atmospheric Hazards and Global Teleconnections: Implications for Multihazard Resilience

Steptoe

Jones

Fox

2018

Reviews of Geophysics

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Occurrences of concurrent extreme atmospheric hazards represent a significant area of uncertainty for organizations involved in disaster mitigation and risk management. Understanding risks posed by natural disasters and their relationship with global climate drivers is crucial in preparing for extreme events. In this review we quantify the strength of the physical mechanisms linking hazards and atmosphere‐ocean processes. We demonstrate how research from the science community may be used to support disaster risk reduction and global sustainable development efforts. We examine peer‐reviewed literature connecting 16 regions affected by extreme atmospheric hazards and eight key global drivers of weather and climate. We summarize current understanding of multihazard disaster risk in each of these regions and identify aspects of the global climate system that require further investigation to strengthen our resilience in these areas. We show that some drivers can increase the risk of concurrent hazards across different regions. Organizations that support disaster risk reduction, or underwrite exposure, in multiple regions may have a heightened risk of facing multihazard losses. We find that 15 regional hazards share connections via the El Niño–Southern Oscillation, with the Indian Ocean Dipole, North Atlantic Oscillation, and the Southern Annular Mode being secondary sources of significant regional interconnectivity. From a hazard perspective, rainfall over China shares the most connections with global drivers and has links to both Northern and Southern Hemisphere modes of variability. We use these connections to assess the global likelihood of concurrent hazard occurrence in support of multihazard resilience and disaster risk reduction goals.

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Indian Ocean Dipole Overrides ENSO’s Influence on Cool Season Rainfall across the Eastern Seaboard of Australia

Cited by 55 publications

References 24 publications

Assessing the impact of large volcanic eruptions of the last millennium (850–1850 CE) on Australian rainfall regimes

Assessing the impact of large volcanic eruptions of the last millennium (850–1850 CE) on Australian rainfall regimes

The influence of topography on midlatitude cyclones on Australia's east coast

Correlations Between Extreme Atmospheric Hazards and Global Teleconnections: Implications for Multihazard Resilience

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