Southwest Monsoon is an important event for India as a whole. There are some oceanic features which play a significant role in controlling as well as driving the Southwest Monsoon. The well-known features include the El Nino, La Nina, IOD (Indian Ocean Dipole). There is another feature which is possibly little known but quite impactful called the MJO (Madden Julien Oscillation).
The MJO is an oceanic atmospheric phenomenon which affects global weather patterns. This is a transitory feature which travels across and in proximity of the Equator. It is a pulse of cloud and rains and has a cycle of about 45 to 60 days.
The presence of MJO in the Indian Ocean becomes very important for the Indian region during Monsoon in particular. While the MJO is seen in other seasons as well, but it holds importance in the Pre Monsoon season is well in terms of controlling rains in Southeast Asia as well as South Asia including the region of Sri Lanka, Indonesia, Maldives and southern parts of India.
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During the Monsoon season, rainfall magnitude rises exponentially due to the combined effects of the other features including La Nina, IOD and MJO when favourable for good rains. In fact, the MJO also has the potential to negate the ill effects of negative IOD and El Nino.
The counter clockwise movement of the MJO reflects an eastward propagation.
The MJO has a cycle of 45-60 days. The magnitude of the MJO is directly proportional to its distance from the centre. The MJO has an inner and an outer circle. As long as it remains in the inner circle, its effect is less but when it comes out, it has the potential to affect weather patterns.
Since the last four days, the MJO is in the Indian Ocean. Wherein the quadrant 2 and 3 are quite favourable for enhancing rains. The MJO entered quadrant 2 and is now in the third quadrant and will shift inward. Thus, rainfall activity has increased over Indonesia, Sri Lanka, Maldives and has even extended up to South India.
In the next couple of days, the rainfall activity over these areas is expected to remain on the higher side before it enters the inner circle and goes inactive.
After it goes into the inner circle, another cycle will begin. Thus, it is expected to come up in the Indian Ocean in June. By then, Southwest Monsoon will have already made an onset over India. Since La Nina will remain neutral and MJO will visit, it is expected to cause good rains over the country then. In fact, Skymet Weather has already forecast June rains to be at 111 percent.
Image Credit: NOAA
Please Note: Any information picked from here must be attributed to skymetweather.com
