Madden-Julian Oscillation
First published: 2005
Brief summary
NOAA resource on the tropical 30-60 day intraseasonal oscillation.
Article
The Madden–Julian Oscillation is a major form of tropical atmospheric variability on intraseasonal timescales. It consists of a broad region of enhanced tropical rainfall followed by a region of suppressed rainfall, and the pattern generally moves eastward through the tropics.
A complete passage commonly takes about 30 to 60 days, although its speed, strength and continuity vary. The active convective phase is accompanied by organised changes in cloudiness, rainfall, winds and atmospheric circulation from the Indian Ocean across the Pacific.
The MJO can influence monsoons, tropical cyclone formation, rainfall extremes and circulation patterns outside the tropics. Its effects depend on the phase and location of the enhanced and suppressed convection, as well as on the background season and climate state.
Operational monitoring uses outgoing longwave radiation, upper- and lower-level winds, velocity potential and multivariate indices. Dynamical and statistical models forecast its movement because the MJO can provide useful guidance for weather risks beyond the usual short-range forecast period.
Source details and credits
- Source / publisher: NOAA CPC
- Source type: Monitoring / educational
- URL type: WWW
- Credits: NOAA CPC
- URL: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml