Syllabus

GS 1: Important Geophysical phenomena

Context: The India Meteorological Department (IMD) noted that, among several large-scale atmospheric-oceanic and local factors, the Madden-Julian Oscillation (MJO) was identified as a key driver for early arrival of southwest monsoon .

More on the News

• The southwest monsoon arrived in Kerala on May 24, which is eight days earlier than the normal onset date.

• It reached Mumbai by May 26, marking an advance of two weeks.

• This was the earliest monsoon arrival in Mumbai ever recorded.

• The India Meteorological Department (IMD) has maintained its April prediction of ‘above normal’ rainfall for the June to September period.

• The IMD now anticipates around 92 cm of rainfall during this southwest monsoon season, which is 106% of the long-period average—slightly higher than the earlier forecast of 91.3 cm (105% of the average) made in April.

• Most parts of India, except the northeastern and northwestern regions, are expected to receive ‘above normal’ rainfall.

Madden-Julian Oscillation (MJO)

• The MJO is a moving system of winds, clouds, and pressure that travels around the equator, bringing periodic rainfall.

• It functions as a slow-moving atmospheric pattern that impacts global tropical and sub-tropical weather.

• It is named after scientists Roland Madden and Paul Julian, who first described it in 1971.

• Typically, it travels eastward at a speed of 4–8 metres per second.

• It completes a circuit around the globe in 30–60 days, though it can extend up to 90 days.