Climate Model Summary

Climate Model Summary Archive: March 2014

An increased chance of El Niño from winter

Currently, the El Niño-Southern Oscillation (ENSO) is neutral. However, the sub-surface of the tropical Pacific Ocean has warmed substantially recently. All international climate models surveyed by the Bureau of Meteorology indicate that the tropical Pacific is likely to continue to warm in coming months, with most models showing surface temperatures either approaching or exceeding El Niño thresholds by August.

El Niño is often, but not always, associated with below-average rainfall during the second half of the year across large parts of southern and inland eastern Australia. Daytime temperatures also tend to be above average over southern Australia.

The Indian Ocean Dipole (IOD) is also neutral. The IOD typically has little impact upon Australian climate throughout the months from December to April. Current model outlooks indicate a neutral IOD through late autumn and early winter. However, the chance of a positive IOD event is elevated during El Niño.

NINO3.4 Outlook

The latest NINO3.4 forecasts (initialised in March) indicate the tropical Pacific is likely to warm over the coming months. Most models indicate El Niño thresholds will be exceeded by August. The most recent NINO3.4 value is –0.1 °C for the week ending 16 March 2014. Sustained NINO3.4 values above +0.8 °C indicate El Niño. The Bureau will continue to monitor the ENSO state closely over the next few months.

Indian Ocean Dipole (IOD)

The IOD index remains neutral with a latest weekly value of –0.3 °C for the week ending 9 March 2014. The IOD typically has little effect on Australian climate during the months from December to April. This is due to the IOD pattern being unable to form once the monsoon trough moves south over the eastern tropical Indian Ocean. Beyond this time outlooks show a neutral IOD. However, the chance of a positive IOD event is elevated during El Niño.

The following graph shows 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.

Predictive Ocean Atmosphere Model for Australia (POAMA)

POAMA, run at the Bureau of Meteorology, generates an eight-monthly forecast on the first day of each month. The most recent model run (started in March) predicts NINO3.4 is most likely to remain within neutral values through til June. Just over 40% of its outlooks exceed El Niño thresholds in August, and just under 60% neutral. The following forecast values (at the top of the table) are for the ensemble mean.

POAMA archive data is available here.

ENSO Dials

The arrows on the dials below indicate the combined average ofmonthly NINO3.4 outlooks from a survey of international global climate models. Note that the individual model runs vary around the average.

ENSO dial month+1 ENSO dial month+3 ENSO dial month+5

NINO3.4 outlook bar-graphs

The following graphs shows the average forecast value of NINO3.4 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.

NINO3.4 bar graph month+1 NINO3.4 bar graph month+3 NINO3.4 bar graph month+5

IOD outlook bar-graphs

The following graph shows 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.

IOD bar graph month+1 IOD bar graph month+3 IOD bar graph month+5

Past climate model summaries