Madden-Julian Oscillation
Thursday, 13. December 2007, 16:58:23
Todays weather forecasts normally only range up to five days ahead. Use of data from the tropical weather pattern known as the Madden-Julian Oscillation may extend this period to up to three weeks.
The Madden-Julian Oscillation was discovered in 1971 by Roland Madden and Paul Julian. It is a large, slowly evolving weather event originating in the tropics that affects weather globally. The Madden-Julian Oscillation is characterised by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean. The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific. This pattern of tropical rainfall then generally becomes very nondescript as it moves over the cooler ocean waters of the eastern Pacific but reappears over the tropical Atlantic and Indian Ocean. The wet phase of enhanced convection and precipitation is followed by a dry phase where convection is suppressed. Each cycle lasts approximately 30-60 days. It is also known as the 40-day wave (or 30-60 day or 40-50 day oscillation). They happen about two to six times a year.
There is a nice animation of how it propagates in phases from the African coast across the Indian Ocean and into the Pacific Ocean (with a speed of 800 km per day) at the Madden-Julian Oscillation Homepage at http://www.apsru.gov.au/mjo/index.asp (Current phase is shown here).
Madden-Julian Oscillation data has revealed their direct influence upon mid-latitude weather, summer monsoons, hurricane development as well as El Niño and La Niña weather events.
More information and simulations at:
http://envam1.env.uea.ac.uk/mjo.html
References:
• http://www.msnbc.msn.com/id/22218289/
• http://www.apsru.gov.au/mjo/index.asp
• http://en.wikipedia.org/wiki/Madden-Julian_oscillation
• http://www-das.uwyo.edu/~geerts/cwx/notes/chap12/mjo.html
The Madden-Julian Oscillation was discovered in 1971 by Roland Madden and Paul Julian. It is a large, slowly evolving weather event originating in the tropics that affects weather globally. The Madden-Julian Oscillation is characterised by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean. The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific. This pattern of tropical rainfall then generally becomes very nondescript as it moves over the cooler ocean waters of the eastern Pacific but reappears over the tropical Atlantic and Indian Ocean. The wet phase of enhanced convection and precipitation is followed by a dry phase where convection is suppressed. Each cycle lasts approximately 30-60 days. It is also known as the 40-day wave (or 30-60 day or 40-50 day oscillation). They happen about two to six times a year.
There is a nice animation of how it propagates in phases from the African coast across the Indian Ocean and into the Pacific Ocean (with a speed of 800 km per day) at the Madden-Julian Oscillation Homepage at http://www.apsru.gov.au/mjo/index.asp (Current phase is shown here).
Madden-Julian Oscillation data has revealed their direct influence upon mid-latitude weather, summer monsoons, hurricane development as well as El Niño and La Niña weather events.
More information and simulations at:
http://envam1.env.uea.ac.uk/mjo.html
References:
• http://www.msnbc.msn.com/id/22218289/
• http://www.apsru.gov.au/mjo/index.asp
• http://en.wikipedia.org/wiki/Madden-Julian_oscillation
• http://www-das.uwyo.edu/~geerts/cwx/notes/chap12/mjo.html
You must be logged in to write a comment. if you're not a registered member, please 
