It is seen that sometimes the dry period with no much weather activity is followed by the active weather phenomemon comprising of convective activity with formation of thunder clouds and precipitation.. One of the factors which influences the above conditions periodically is Madden Julian Oscillation (MJO). Itis the major fluctuation in tropical weather on weekly to monthly timescales.
What is Madden Julian Oscillation?
MJO is a eastward travelling pattern of period with moderate to strong weather activity followed by the period of less or no activity. It is a pulse of clouds and rainfall near the equator which propagates with the speed upto 29 kmph over the warm waters of Pacific and Indian ocean. Each cycle lasts approximately 30–60 days and sometimes 90 days.
The effect of the MJO is witnessed mainly in the tropical region, in the band between 30 degrees North and 30 degrees South of the equator.
Why the name Madden Julian?
In 1971 two scientists Roland Madden and Paul Julian identified this phenomenon. who worked at the National Centre for Atmospheric Research in Boulder, Colorado.
How MJO affects India?
Madden Julian Oscillation affects India in two ways. Firstly affecting the onset of monsoon and rainfall activity during monsoons. It means in active phase it brings excess rainfall and while in suppressed phase it gives deficient rainfall.
Secondly formation of tropical cyclones in Indian waters.
Image source: UCAR EDU
The above diagram shows box in which blue region shows the active MJO with enhanced rainfall activity while the orange region shows the dry phase with sunny weather.