Madden-Julian Oscillation (MJO)

Source: IE

Context: The Madden-Julian Oscillation (MJO) played a key role in triggering the early onset of the southwest monsoon in Kerala and Mumbai.

About Madden-Julian Oscillation (MJO):

• What is MJO?

• The MJO is an eastward-moving tropical atmospheric disturbance involving clouds, rainfall, winds, and pressure patterns. Discovered in 1971 by Roland Madden and Paul Julian, it typically completes a global circuit every 30–60 days. It features two alternating phases: Enhanced Convective Phase: Characterized by increased rainfall and greater cloud formation due to rising air and moisture convergence. Suppressed Convective Phase: Marked by reduced rainfall and clearer skies, as sinking dry air inhibits cloud development.

• The MJO is an eastward-moving tropical atmospheric disturbance involving clouds, rainfall, winds, and pressure patterns.

• Discovered in 1971 by Roland Madden and Paul Julian, it typically completes a global circuit every 30–60 days.

• It features two alternating phases: Enhanced Convective Phase: Characterized by increased rainfall and greater cloud formation due to rising air and moisture convergence. Suppressed Convective Phase: Marked by reduced rainfall and clearer skies, as sinking dry air inhibits cloud development.

• Enhanced Convective Phase: Characterized by increased rainfall and greater cloud formation due to rising air and moisture convergence.

• Suppressed Convective Phase: Marked by reduced rainfall and clearer skies, as sinking dry air inhibits cloud development.

• How is MJO Formed?

• Surface convergence of winds initiates rising air motion in the tropics. This leads to condensation and cloud formation, supported by upper-level divergence. The entire dipole system moves from west to east across the equator, especially between 30°N and 30°S latitude.

• Surface convergence of winds initiates rising air motion in the tropics.

• This leads to condensation and cloud formation, supported by upper-level divergence.

• The entire dipole system moves from west to east across the equator, especially between 30°N and 30°S latitude.

• Factors Influencing MJO:

• Sea Surface Temperature (SST) anomalies, particularly in the Indian and Pacific Oceans. Atmospheric moisture content and zonal wind anomalies. Seasonal conditions like El Niño, which can amplify or suppress MJO activity.

• Sea Surface Temperature (SST) anomalies, particularly in the Indian and Pacific Oceans.

• Atmospheric moisture content and zonal wind anomalies.

• Seasonal conditions like El Niño, which can amplify or suppress MJO activity.

• Impacts of MJO: On Indian Monsoon:

• On Indian Monsoon:

• MJO in its active phase over the Indian Ocean can:

• Trigger early monsoon onset, as seen in 2024 and 2025.

• Boost cyclogenesis and increase rainfall intensity during its passage.

• Improve intra-seasonal rainfall variability and monsoon breaks.

• Global Influence:

• Modulates cyclone frequency and strength across ocean basins. Alters jet streams, influencing weather extremes in the U.S., Europe, and Australia. Can cause cold surges, heatwaves, and floods in mid-latitude regions. Acts as a short-term climate modulator unlike ENSO, which has seasonal effects.

• Modulates cyclone frequency and strength across ocean basins.

• Alters jet streams, influencing weather extremes in the U.S., Europe, and Australia.

• Can cause cold surges, heatwaves, and floods in mid-latitude regions.

• Acts as a short-term climate modulator unlike ENSO, which has seasonal effects.