Madden-Julian Oscillation (MJO)

The Madden-Julian Oscillation (MJO) is the major fluctuation in tropical weather on weekly to monthly timescales. The MJO can be characterised as an eastward moving 'pulse' of cloud and rainfall near the equator that typically recurs every 30 to 60 days.


MJO phase diagram

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*Note: There are missing satellite observations from 16/3/1978 to 31/12/1978.

The MJO phase diagram illustrates the progression of the MJO through different phases, which generally coincide with locations along the equator around the globe. RMM1 and RMM2 are mathematical methods that combine cloud amount and winds at upper and lower levels of the atmosphere to provide a measure of the strength and location of the MJO. When the index is within the centre circle the MJO is considered weak, meaning it is difficult to discern using the RMM methods. Outside of this circle the index is stronger and will usually move in an anti-clockwise direction as the MJO moves from west to east. For convenience, we define 8 different MJO phases in this diagram.

Average weekly rainfall probabilities

These maps show average weekly rainfall probabilities and expected 850 hPa (approximately 1.5 km above sea level) wind anomalies for each of the 8 MJO phases. Green and blue shading indicates higher than normal rainfall would be expected, while red and orange shading indicates lower than normal rainfall would be expected. The direction and length of the arrows indicate the direction and strength of the wind anomaly. The darker the arrow, the more reliable the information is. The relationship of the MJO with Australian rainfall and winds changes with the season (which can be selected at the top).

Average outgoing longwave radiation (OLR)

Outgoing longwave radiation (OLR) is often used as a way to identify tall, thick, convective rain clouds. These maps show the difference from expected cloudiness based on the position of the MJO. The violet and blue shading indicates higher than normal, active or enhanced tropical weather, while orange shading indicates lower than normal cloud or suppressed conditions. The direction and length of the arrows indicate the direction and strength of the wind anomaly. The darker the arrow, the more reliable the information is. The relationship of the MJO with tropical weather patterns changes with the season (which can be selected above the maps).

Global maps of outgoing longwave radiation (OLR)

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Global maps of outgoing longwave radiation (OLR) highlight regions experiencing more or less cloudiness. The top panel is the total OLR in Watts per square metre (W/m²) and the bottom panel is the anomaly (current minus the 1979-1998 climate average), in W/m². In the bottom panel, negative values (blue shading) represent above normal cloudiness while positive values (brown shading) represent below normal cloudiness.

Regional maps of outgoing longwave radiation (OLR)

Click on the boxes to view a timeseries of cloudiness for that region.
Map of regional cloudiness Dateline Vanuatu Coral Sea Fiji Nauru & Tuvalu Solomon Islands New Guinea Northern Australia Micronesia Malaysia & Indonesia Guam & Marianas Philippines Indochina Southern India & Sri Lanka

Below: OLR totals over the dateline

Click to see full-size graph of OLR totals over the dateline.

The graphs linked to this map show the OLRs for the different regions within the Darwin RSMC area. The horizontal dashed line represents what is normal for that time of year (based on the 1979 to 1998 period). The coloured curve is the 3-day moving average OLR in W/m². Below normal OLR indicates cloudier than normal conditions in this particular area, and is shown in blue shading. Above normal OLR indicates less cloudy conditions and is shown in yellow shading.

Daily averaged OLR anomalies

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Westerly wind anomalies

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Time-longitude plots of daily averaged OLR anomalies (left) and 850 hPa (approximately 1.5 km above sea level) westerly wind anomalies (right) are useful for indicating the movement of the MJO.

How to read the Time-Longitude plots

The vertical axis represents time with the most distant past on the top and becoming more recent as you move down the chart. The Horizontal axis represents longitude.

Eastward movement of a strong MJO event would be seen as a diagonal line of violet (downward from left to right) in the OLR diagram, and a corresponding diagonal line of purple in the wind diagram. These diagonal lines would most likely fall between 60°E and 150°E and they would be repeated nearly every 1 to 2 months.

Significant rainfall over Bangladesh

The past week saw a strengthening in southwesterly monsoon flow over Bangladesh and western Myanmar, delivering large rainfall totals. The active monsoon conditions became more intense with a tropical low, which sat near Bangladesh for much of the past week. Rangamati, a hilly district in Bangladesh's southeast, was particularly affected, with 343 mm recorded over 24 hours to the morning of Tuesday 13 June, more than half their June monthly average rainfall in a single day. This heavy rain triggered multiple landslides across the southeast of the country, with loss of life and damage to infrastructure recorded.

Meanwhile, the Southwest Monsoon continued its northward progression over India. The northern limit of the monsoon is now over the central districts, slightly further south than its average position for this time of year. The focus of last week’s rainfall over the Indian subcontinent was in central and northeastern regions, associated with a trough and tropical low. Follow the progress of the Southwest Monsoon on the India Meteorological Department's monsoon page.

Madden–Julian Oscillation maintains strength over western hemisphere

The Madden–Julian Oscillation (MJO) signal maintained moderate strength as it moved over the western hemisphere and Africa over the past week. This has seen increased cloudiness and rainfall over central and western Africa. Impacts over eastern Africa, where the MJO signal is usually best defined, have been minimal, with no break in the severe drought affecting the region.

Most international climate models forecast the MJO to rapidly weaken over coming days as it moves eastward, while others forecast it to maintain at moderate strength as it moves over the Indian Ocean. If the MJO maintains its strength over the western Indian Ocean, rainfall would typically be enhanced over parts of the Indian subcontinent. There would also be an increased chance of tropical cyclone development in the area.

With the MJO over the far western Indian Ocean, there is typically little effect for northern Australia at this time of the year. However if the MJO maintains moderate strength while moving further east across the Indian Ocean, there is an increased chance of onshore flow along the north Queensland coast and thus enhanced rainfall.

See the Bureau's current MJO monitoring for more information.

El Niño WATCH cancelled; ENSO neutral likely for 2017

The Bureau's ENSO Outlook has been downgraded from El Niño WATCH to INACTIVE, after an easing of climate model outlooks, and a reversal of the early autumn warming seen in the eastern tropical Pacific Ocean. All eight international climate models surveyed by the Bureau of Meteorology now suggest tropical Pacific Ocean temperatures are likely to remain ENSO-neutral for the second half of 2017, compared to seven of eight models that were forecasting a possible El Niño event in April.

The Indian Ocean Dipole (IOD) remains neutral. Three out of six climate models suggest a positive IOD will develop during the Australian winter. A positive IOD is typically associated with drier than average conditions over much of central Australia and parts of northern Australia during the September to November build-up.

See the Bureau’s ENSO Wrap-Up for more about El Niño, La Niña and the Indian Ocean Dipole.

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ACKNOWLEDGEMENT: Interpolated OLR data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA.

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