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.