Why in the News?
Mumbai got heavy monsoon rains two weeks early because of a strong Madden-Julian Oscillation (MJO) — a weather pattern that boosts rainfall in the region.
About the Madden-Julian Oscillation (MJO):
- Definition: The MJO is a moving weather system of clouds, wind, rain, and pressure that travels eastward around the tropics.
- Cycle Time: It takes 30 to 60 days to complete a full loop around the globe.
- Discovery: It was discovered in the 1970s by Roland Madden and Paul Julian.
- Two Phases:
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- The enhanced convective phase brings heavy rain, storms, and clouds.
- The suppressed convective phase brings dry, clear weather.
- Global Pattern: These phases move together — when one area gets rain, another gets dry weather.
- MJO vs ENSO: Unlike El Niño, which lasts for months, the MJO changes every few weeks and affects short-term weather patterns.
- Wider Impact: It influences monsoons, cyclones, jet streams, and weather in both tropical and non-tropical regions.
- Phases: Scientists divide its movement into 8 phases, each showing where rain or dry weather will occur.
MJO and the Early Monsoon of 2025:
- Early Monsoon Trigger: The early arrival of the monsoon in May 2025 was largely due to a very active MJO.
- IMD Observation: The India Meteorological Department noted that the MJO was in Phase 4 with high amplitude, which strongly affects Indian rainfall.
- Rapid Monsoon Progress: It helped push extra moisture and clouds from the Indian Ocean, making the monsoon move from Kerala to Maharashtra in just two days.
- Other Contributing Factors:
- A strong cross-equatorial flow brought warm, moist air from the south.
- A low-pressure system in the Arabian Sea brought pre-monsoon rains to Mumbai.
- Record Rainfall: This resulted in Mumbai’s wettest May in over 100 years.
- Why It Matters: The event showed how a tropical system like the MJO can suddenly change monsoon timing and rainfall patterns in India.
| [UPSC 2017] With reference to ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?
1. IOD phenomenon is characterized by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean. 2. An IOD phenomenon can influence an El Nino’s impact on the monsoon. Options: (a) 1 only (b) 2 only* (c) Both 1 and 2 (d) Neither 1 nor 2 |
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