Seasonal climate summary for the southern hemisphere (spring 2017): equal-fifth warmest spring on record, with rainfall mixed

Tobin, Skie

doi:10.1071/es19037

Cited by 4 publications

(3 citation statements)

References 22 publications

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“…The 5VAR Index fell below þ1 from July 2017 ( Fig. 2), which is consistent with a neutral ENSO (Tobin 2020) and the onset of a weak La Niña in the latter stages of 2017 (Tihema 2019). NINO3.4 values were below zero from July 2016 until early 2017 (Trewin 2018a).…”

Section: Composite Monthly Enso Index (5var)supporting

confidence: 70%

Seasonal climate summary for the southern hemisphere (autumn 2018): a weak La Niña fades, the austral autumn remains warmer and drier

Chapman

Rosemond

2020

J. South. Hemisph. Earth Syst. Sci.

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This is a summary of the austral autumn 2018 atmospheric circulation patterns and meteorological indices for the southern hemisphere, including an exploration of the season’s rainfall and temperature for the Australian region. The weak La Niña event during summer 2017–18 was in retreat as the southern hemisphere welcomed the austral autumn, and before midseason, it had faded. With the El Niño Southern Oscillation and the Indian Ocean Dipole in neutral phases, their influence on the climate was weakened. Warmer than average sea surface temperatures dominated much of the subtropical South Pacific Ocean and provided favourable conditions for the formation of a rare subtropical cyclone over the southeast Pacific Ocean in May. The southern hemisphere sea ice extent was slightly below the autumn seasonal average. The southern hemisphere overall during autumn was drier and warmer than the seasonal average. The season brought warmer than average temperatures and average rains to parts of the continents of Africa and South America. Australia recorded its fourth-warmest autumn, partly due to an intense, extensive and persistent heatwave, which occurred during the midseason. An extraordinary and record-breaking rainfall event occurred over Tasmania’s southeast, under the influence of a negative Southern Annular Mode. The mainland’s northeastern tropical region was wetter than average as a result of tropical cyclones, which formed during an active monsoon. These areas, however, were in contrast to the rest of the continent, which followed the trend of the previous season and remained drier than average; consequently, rainfall deficiencies emerged across the southern half of Australia, and some areas witnessed an increase in extent and severity of these deficiencies.

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Section: Composite Monthly Enso Index (5var)supporting

confidence: 70%

Seasonal climate summary for the southern hemisphere (autumn 2018): a weak La Niña fades, the austral autumn remains warmer and drier

Chapman

Rosemond

2020

J. South. Hemisph. Earth Syst. Sci.

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“…We used the SOI provided by the Australian Bureau of Meteorology ( http://www.bom.gov.au/climate/enso ). The method the Bureau of Meteorology uses to calculate the SOI is based on mean and standard deviation of the pressure differences between Tahiti and Darwin, with the climatology period based on a dataset from 1933 to 1992 29 . Sustained negative (below − 7) or positive (above + 7) SOI values typically indicate El Niño or La Niña events, respectively.…”

Section: Methodsmentioning

confidence: 99%

The El Niño Southern Oscillation drives multidirectional inter-reef larval connectivity in the Great Barrier Reef

Gurdek-Bas

Benthuysen

Harrison

et al. 2022

Sci Rep

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The El Niño Southern Oscillation (ENSO) is the strongest source of interannual global climate variability, and extreme ENSO events are projected to increase in frequency under climate change. Interannual variability in the Coral Sea circulation has been associated with ENSO, although uncertainty remains regarding ENSO's influence on hydrodynamics and larval dispersal in the adjacent Great Barrier Reef (GBR). We investigated larval connectivity during ENSO events from 2010 to 2017 throughout the GBR, based on biophysical modelling of a widespread predatory reef fish, Lutjanus carponotatus. Our results indicate a well-connected system over the study period with high interannual variability in inter-reef connectivity associated with ENSO. Larval connectivity patterns were highly correlated to variations in the Southern Oscillation Index (SOI). During El Niño conditions and periods of weak SOI, larval dispersal patterns were predominantly poleward in the central and southern regions, reversing to a predominant equatorward flow during very strong SOI and extreme La Niña conditions. These ENSO-linked connectivity patterns were associated with positive connectivity anomalies among reefs. Our findings identify ENSO as an important source of variation in larval dispersal and connectivity patterns in the GBR, which can influence the stability of population dynamics and patterns of biodiversity in the region.

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“…For the DMI, a 3-month running average was used to smooth the time series. When the DMI is higher (lower) than +0.4 • C (−0.4 • C) for at least 3 months, positive (negative) IOD events occur (Cahyarini et al, 2021;Tobin, 2020).…”

Section: Climate Modesmentioning

confidence: 99%

Analyzing future marine cold spells in the tropical Indian Ocean: Insights from a regional Earth system model

Dinesh,

Kumar,

Mishra

et al. 2024

Quart J Royal Meteoro Soc

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In this study, a future projection of marine cold spells (MCSs) over the tropical Indian Ocean is made using a fully coupled regional Earth system model, namely ROM, under two representative concentration pathways (RCPs): RCP4.5 and RCP8.5. In both RCPs, the future MCS properties have been estimated across three distinct time intervals: the near future (NF; 2010–2039), the middle future (MF; 2040–2069), and the far future (FF; 2070–2099). The future MCS computations were examined with respect to fixed historical baseline periods and varying baseline periods. MCSs were frequent, intense, and prolonged during the historical period. ROM effectively simulated these historical MCS metrics and their trends and outperformed the forcing general circulation model as well as the multimodel ensemble mean of Coupled Model Intercomparison Project phase 5 models. In the future, MCSs will cease to occur in ∼13% (4%), ∼56% (66%) and ∼69% (93%) of the area of the tropical Indian Ocean in the NF, MF, and FF respectively under the RCP4.5 (RCP8.5) scenario using a fixed historical baseline period. This departure of MCSs led to the disappearance of events, first identified over the Arabian Sea in both RCPs. The decrease in net heat flux and increase in wind speed contribute to the genesis and severity of MCS events. Further, during the El Niño regime, the MCS events dramatically decrease due to the basin‐wide warming, but during the La Niña phase, the MCS intensity and spatial range increase. This study further investigates the sensitivity of MCSs with the choice of baseline period. Adopting varying baseline periods over time does not result in the disappearance of MCSs but does produce declining trends in MCS activity, highlighting the need for careful consideration in choosing a baseline period.

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Seasonal climate summary for the southern hemisphere (spring 2017): equal-fifth warmest spring on record, with rainfall mixed

Cited by 4 publications

References 22 publications

Seasonal climate summary for the southern hemisphere (autumn 2018): a weak La Niña fades, the austral autumn remains warmer and drier

Seasonal climate summary for the southern hemisphere (autumn 2018): a weak La Niña fades, the austral autumn remains warmer and drier

The El Niño Southern Oscillation drives multidirectional inter-reef larval connectivity in the Great Barrier Reef

Analyzing future marine cold spells in the tropical Indian Ocean: Insights from a regional Earth system model

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