The Madden Julian Oscillation (MJO) is an equatorial travelling pattern of anomalous rainfall that is planetary in scale. The MJO can be defined as an eastward movement of clouds, rainfall, winds and pressure near the equator that typically recurs every 30 to 60 days. The MJO moves eastward at 5 meters per second across the tropics, crossing the tropics in 30-60 days. the The wet phase of enhanced convection and precipitation is followed by a dry phase where thunderstorm activity is suppressed. Because of this period the MJO is also known as 30-60 day oscillation, 30-60 day wave or interseasonal oscillation.
The two phases :-
In the enhanced or convective phase winds at the surface converges and the air is pushed up throughout the atmosphere and at the top wind diverges causing the thunderstorms supporting the Indian monsoon. In the suppressed phase the air converges at the top and sinks and diverges at the bottom causing the clear skies without of negligible rainfall.
Important facts of MJO in the meteorological :-
- Indian Ocean Dipole, El-Nino and MJO are coupled atmospheric-oceanic phenomenon in which the IOD in confined to Indian Ocean while other two effects the global rainfall petterns.
- IOD and ENSO remains in respective positions while the MJO is traversing phenomenon.
- Shorter the MJO duration batter the Indian monsoon.
- As the MJO progress eastward region the tropical cyclone activities also shifts eastward from the western Pacific to the Eastern pacific and finally to the Atlantic basin.
- The MJO over a series of months in the Western pacific can speed up the development of an El-Nino or La-Nina events but do not leads to the onset to them.
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