What is the Madden-Julian Oscillation (MJO)?
The Madden-Julian Oscillation (MJO) is a major intra-seasonal atmospheric variability phenomenon in the tropical atmosphere, discovered in 1971 by Roland Madden and Paul Julian. It is characterized by an eastward-moving pulse of clouds, rainfall, winds, and pressure anomalies that travels around the globe's tropics on much shorter timescales than other climate patterns.pmfias
Key Characteristics
Temporal Scale: The MJO operates on a 30 to 60-day cycle, making it a short-term atmospheric phenomenon distinct from long-term oscillations like El Niño. The oscillating system travels eastward at approximately 3-8 meters per secondacross the tropical regions, completing a full circuit around the equator in roughly 40 days.psl.noaa+3
Spatial Pattern: The MJO is most prominent over the Indian and Pacific Oceans, with the convectively active stage typically starting over the equatorial Indian Ocean and moving slowly eastward toward the central Pacific. The phenomenon operates between 30°N and 30°S latitude.nextias+2
The Two Phases of MJO
The oscillation consists of distinct phases with opposing weather characteristics:
Enhanced (Convective) Phase: During this stage, surface winds converge, causing air to rise throughout the atmosphere. As the ascending air cools and condenses, it produces heavy rainfall, clouds, and enhanced convective activity. At the top of the atmosphere, winds diverge, facilitating further upward motion.drishtiias
Suppressed (Dry) Phase: In this phase, upper-atmosphere winds converge, forcing air to sink and then diverge at the surface. This downward motion causes the air to warm and dry, resulting in reduced rainfall, clear skies, and suppressed convection. The entire dipole structure (active and suppressed phases together) moves eastward, creating a traveling pattern of wet and dry conditions across the tropics.drishtiias
Global Impacts
The MJO has wide-ranging influences on global weather patterns:
Tropical Cyclones: It alters the frequency and intensity of tropical cyclones in the Pacific, Indian Ocean, and Atlantic basins.pmfias
Monsoon Systems: The MJO significantly affects the Indian monsoon. When the active phase occurs over the Indian Ocean during the monsoon season, it enhances rainfall across India. Conversely, when the MJO phases over the Pacific Ocean, it can suppress Indian monsoon rainfall.nextias
ENSO Modulation: While the MJO does not directly cause El Niño or La Niña events, it can trigger or suppress these oscillations and contribute to their development speed and intensity.cpc.ncep.noaa+1
Extratropical Effects: The MJO influences weather far beyond the tropics, affecting precipitation and temperature patterns over all seven continents, including distant regions like Europe, North America, and even Antarctica. During Northern Hemisphere winter, the MJO can increase heavy precipitation along the US west coast and intensify cold air outbreaks across the eastern US.tandfonline+1
Significance for Climatology and Weather Forecasting
Understanding the MJO is crucial for weather prediction and climate analysis because it provides predictability for weekly to monthly weather forecasts in tropical and subtropical regions. The MJO's eight distinct phases allow scientists and meteorologists to track where enhanced rainfall or dry conditions will occur, making it valuable for agricultural planning, water resource management, and forecasting extreme weather events.
- https://www.pmfias.com/madden-julian-oscillation/
- https://www.psl.noaa.gov/mjo/MJOprimer/
- https://www.nextias.com/blog/madden-julian-oscillation/
- https://testbook.com/ias-preparation/madden-julian-oscillation
- https://www.drishtiias.com/daily-news-analysis/madden-julian-oscillation-mjo
- https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/MJO_1page_factsheet.pdf
- https://www.tandfonline.com/doi/full/10.1080/07055900.2025.2522833?src=
- https://climate.ai/blog/the-mjo-a-climate-supervillian/
- https://www.civilsdaily.com/news/what-is-madden-julian-oscillation-mjo/
- https://www.pib.gov.in/newsite/erelcontent.aspx?relid=62398
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