Understanding the Dynamical Relation of MJO with Indian Summer Monsoon Onset and Progress

Madden–Julian oscillation (MJO) is an important oceanic and atmospheric phenomenon in the tropical belt around the globe which influences the global weather & climate system. The process mainly results east ward propagating band of rain clouds and its circulation pattern has a remarkable effect on the global annual rainfall. Monsoon onset is important as the rainfall transition and its progress has direct impact on the sectors like agriculture, water, health and economy etc. over the continent of India. As there are different phases in the MJO so it clearly affects the intra-seasonal and inter seasonal variability of rainfall, like for few phases it gives monsoon break type rainfall distribution whereas for some other phases it gives active rainfall distribution. It is also possible that the MJO phases have direct impact on the dynamics and physics during the onset as well as the progress of south west monsoon in India. In this study the association of different MJO phases and the resultant rainfall dynamics during onset period are analyzed using the multi-source weather observations for 68 years (1951-2018). The link of both active and weak phase of MJO and rainfall (duration and intensity) during the onset phases and thereafter during the progress of monsoon are quantified and presented. Also the spatial relation of the MJO location and the regional rainfall along with other oceanic parameters like Sea Surface Temperature, heat flux etc. are evaluated using the observed and reanalysis product. It is observed that mostly the active (weak) phase leads to early (late) onset over Kerala coast in India. Finally the tele-connection of progress of monsoon in continental India and the MJO phases are discussed. This association study will certainly help the researchers in better understanding of the MJO and regional rainfall dynamics and this information can be integrated with numerical weather prediction models for better and accurate prediction of the monsoon onset as well as the rainfall in the sub continent.