Climate Model Summary
Model Summary forecasts are no longer available
We are streamlining some climate pages including removal of the Model Summary.
From 10 December our climate information is available on the Southern Hemisphere monitoring and Southern Hemisphere outlooks pages.
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Average of international model outlooks for the Niño3.4 index
Average of international model outlooks for the Indian Ocean Dipole (IOD) index
Dial details
The arrows on the dials indicate the combined average of monthly outlooks from a survey of international global climate models. Note that the individual model runs vary around the average.
The ENSO and IOD dials are calculated by simply averaging the ensemble means from all the models surveyed. Values are not representative of the potential spread of the forecast outcomes. Therefore, the dials are intended to be used as a quick reference to determine whether the models are showing a warming trend, a cooling trend, or neither. More information is provided in the graphs presented in other sections.
More information:
Niño3.4 covers the central Pacific region.
Niño3.4 multi-model forecast for the months ahead
Bar graph details
The graphs are based on the ensemble mean for the most recent model run.
These graphs show the average forecast value of Niño3.4 for each international model surveyed for the selected calendar month. If the bars on the graph are approaching or exceeding the blue dashed line, there is an increased risk of La Niña. Similarly, if the bars on the graph are approaching or exceeding the red dashed line, there is an increased chance of El Niño.
Niño3.4 recent observations and multi-model long-range forecast
Timeseries graph details
This timeseries graph shows recent monthly observations, as well as long-range forecasts for the Niño3.4 index from a range of international models. Monthly observations are from the OISSTv2 (1991-2020 base period) dataset, represented by the left side dashed line. Each coloured line to the right represents the ensemble mean forecast from nine international climate models including the Bureau's model. The graph is updated each month, with available data updated fortnightly.
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IOD index multi-model forecast for the months ahead
Bar graph details
The graphs are based on the ensemble mean for the most recent model run.
These graphs show the average forecast value of the IOD index for each international model surveyed for the selected calendar month. If the majority of models are approaching or exceeding the blue dashed line, then there is an increased risk of a negative IOD event. If the majority of models are approaching or exceeding the red dashed line, then there is an increased risk of a positive IOD event.
More information:
Sea surface temperature graphs
Australian climate is influenced by sea surface temperature and atmospheric patterns in the Pacific, Indian and Southern ocean regions. Specific regions are monitored, as they can indicate the presence, or potential development, of ENSO (El Niño/La Niña), Indian Ocean Dipole (IOD) phases and Southern Annular Modes. Pacific and Indian ocean indices are updated fortnightly, but the SAM index can change rapidly so it is updated daily. The first SAM button matches the Niño and IOD fortnightly issue date. During the following fortnight the 'Latest SAM' chart will diverge.
Niño34 predictions for the next 5 months
Niño34 probabilities
Product code: IDCK000073
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Model details
Model selection
All the models included in this page have been documented in the peer-reviewed international scientific literature and have skill in predicting El Niño-Southern Oscillation (ENSO) and Indian Ocean patterns. They are all coupled General Circulation Models, and hence simulate both atmospheric and oceanic processes using physics rather than statistics. Most have been run routinely for a number of years and are subject to regular revision and update with the aim of continuous improvement. They represent the state-of-the-art of climate prediction systems and offer useful guidance up to about nine months. The majority of models used in our survey are formally recognised by the World Meteorological Organization as Global Producing Centres for long-range forecasts.
All models use an ensemble method, where several forecasts are run at the same time using slightly different initial conditions. While all models use ensemble techniques, the number of ensembles differs for each model.
The data presented on these pages is the 'ensemble mean' which is the average of all the model-runs performed by each model, each month. The ensemble mean therefore flattens out the potential forecast outcomes and doesn't show the full spread of the possible forecast scenarios.
More information about these models
[an error occurred while processing this directive]The webpage
This webpage surveys the latest output from several reputable climate models developed at leading international climate agencies. Data from these models is analysed and displayed in graphs and dials to show how temperature patterns in the Indian and Pacific ocean are likely to change over the coming six-months. These patterns in the oceans have been shown to have a significant impact on Australian temperature and rainfall patterns (e.g. cooling of the tropical Pacific Ocean during La Niña events is typically associated with increased rainfall and cooler daytime temperatures in Australia).
When the models are in agreement, then there is higher confidence in the model outlooks. When the models are showing a large spread or large variety of outcomes, there is a larger amount of uncertainty associated with the forecast.
The models
All the models included in this page have been documented in the peer-reviewed international scientific literature and have skill in predicting El Niño-Southern Oscillation (ENSO) and Indian Ocean patterns. They are all coupled General Circulation Models, and hence simulate both atmospheric and oceanic processes using physics rather than statistics. Most have been run routinely for a number of years and are subject to regular revision and update with the aim of continuous improvement. They represent the state-of-the-art of climate prediction systems and offer useful guidance up to about nine months. The majority of models used in our survey are formally recognised by the World Meteorological Organization as Global Producing Centres for long-range forecasts.
Update schedule
The Climate Model Summary is updated on the 12th of each month (or the next working day following the 12th) when model data becomes available. Data for the Bureau's model, ACCESS–S, is updated fortnightly along with several other models that also provide more frequent updates during the month.
The ensemble technique
All models use an ensemble method, where several forecasts are run at the same time using slightly different initial conditions. While all models use ensemble techniques, the number of ensembles differs for each model.
Important note
The data presented on these pages is the 'ensemble mean' which is the average of all the model-runs performed by each model, each month. The ensemble mean therefore flattens out the potential forecast outcomes and doesn't show the full spread of the possible forecast scenarios.
The dials
The ENSO and IOD dials (from the Overview section) are calculated by simply averaging the ensemble means from all the models surveyed. Values are not representative of the potential spread of the forecast outcomes. Therefore, the dials are intended to be used as a quick reference to determine whether the models are showing a warming trend, a cooling trend, or neither. More information is provided in the graphs presented in other sections.
Background information
Related sites
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History
Model data are provided for Bureau of Meteorology use by the agencies detailed in Model Summary – Models. Respective agency copyright applies to these data.
Positive IOD continues, but influence likely to weaken in summer
The positive IOD (Indian Ocean Dipole) remains active, and is likely to maintain strong positive IOD index values until at least the end of spring.
A positive IOD typically means below average winter–spring rainfall for much of southern and central Australia. IOD events are unable to form, and therefore influence Australian climate, during the summer months once the monsoon trough transitions into the southern hemisphere. Therefore, the prolonged dry signal over Australia is likely to weaken during summer.
The El Niño–Southern Oscillation (ENSO) is currently neutral. The latest outlooks from the surveyed models suggest that ENSO-neutral is the most likely scenario for the remainder of 2019 and into 2020.
NINO3.4 outlook
The latest weekly NINO3.4 value to 8 September is −0.1 °C, meaning the central tropical Pacific Ocean remains within neutral-ENSO bounds. All eight surveyed models suggest the central tropical Pacific (NINO3.4) is likely to remain neutral with respect to the El Niño–Southern Oscillation (ENSO) from September through to January 2020.
Persistent NINO3.4 values above +0.8 °C typically indicate El Niño, while values below −0.8 °C typically indicate La Niña.
Indian Ocean Dipole (IOD) outlook
Sea surface temperatures in the Indian Ocean have shown patterns consistent with a positive IOD event since the end of May. The IOD index has been above the positive IOD threshold for 7 of the last 8 weeks, with the latest weekly value (to 8 September) well above the threshold at +1.0 °C. This is a result of cooler than average sea surface temperatures off the Java coast and warmer than average temperatures off the Horn of Africa.
All models suggest positive IOD index values are likely to persist into summer, however, IOD events are unable to form (and therefore influence Australian climate) once the monsoon trough moves into the southern hemisphere, usually from December to April.
A positive IOD typically means a drier than average winter-spring for parts of southern and central Australia. It also typically means warmer than average winter-spring days for the southern two-thirds of Australia and an early start to the southern bushfire season. Persistent IOD index values above +0.4 °C typically indicate a positive IOD event, while values below −0.4 °C typically indicate a negative IOD event.
Australian Community Climate Earth-System Simulator–Seasonal (ACCESS–S)
The Bureau of Meteorology's climate model generates a six-month forecast for the NINO and IOD indices each fortnight.
The most recent model run (generated 31 August) suggests the central tropical Pacific sea surface temperatures will remain close to average throughout the outlook period, but warm gradually. For the Indian Ocean Dipole (IOD), the Bureau's model suggests positive IOD values are likely to persist throughout spring, peaking in September and returning to average during the southern summer.
The forecast values, shown below in bold, are for the model's ensemble mean.
Product code: IDCKGL0000
Unless otherwise noted, all maps, graphs and diagrams in this page are licensed under the Creative Commons Attribution 4.0 International Licence
