Madden-Julian Oscillation (MJO)
Context: A favourable Madden-Julian Oscillation (MJO) phase over the Indian Ocean in May 2025 played a critical role in enhancing convection and rainfall activity, contributing significantly to the unusually early onset of the southwest monsoon over Kerala on May 24.
Important Pointers:
Madden-Julian Oscillation (MJO): An eastward-moving atmospheric disturbance of clouds, winds, and pressure near the equator, affecting global and Indian weather patterns.
Influence on Indian Monsoon: When in a favourable phase over the Indian Ocean, MJO enhances rainfall during the southwest monsoon season.
Speed and Cycle: MJO moves eastward at 4–8 m/s and completes a global circuit in 30–60 days.
Impact on Monsoon Onset (2025): A favourable MJO phase contributed to the early onset of monsoon over Kerala on May 24, eight days ahead of schedule.
Enhanced Convection: MJO increases vertical transport of heat and moisture (convection), promoting cloud formation and precipitation.
Global Reach: Though it originates in the Indian Ocean, MJO affects weather worldwide, including hurricanes, typhoons, and cyclones.
Difference from ENSO: Unlike El Niño-Southern Oscillation (ENSO), MJO is intra-seasonal (short-term) and does not have a fixed periodicity.