The Madden-Julian Oscillation (MJO) is an equatorial traveling pattern of anomalous rainfall that is planetary in scale. The mechanism and cause of the MJO is as yet not well-understood and is a subject of ongoing study.
The MJO is characterized by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean. The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific. This pattern of tropical rainfall then generally becomes very nondescript as it moves over the cooler ocean waters of the eastern Pacific but reappears over the tropical Atlantic and Indian Ocean. The wet phase of enhanced convection and precipitation is followed by a dry phase where convection is suppressed. Each cycle lasts approximately 30-60 days.
The MJO is also known as the 30-60 day oscillation, 30-60 day wave, or intraseasonal oscillation.
* 1 Atmospheric patterns
* 2 North American winter effects
o 2.1 Pineapple Express events
* 3 Boreal Summer Effects
* 4 Tropical cyclone influence
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