Investigating a Tropical Weather Pattern with Global Reach

September 27, 2011
An unprecedented study in the Indian Ocean will examine how the Madden-Julian Oscillation forms.
An unprecedented study in the Indian Ocean will examine how the Madden-Julian Oscillation forms.

As it moves across the Indian Ocean, the Madden-Julian Oscillation (MJO) can bring torrential rains to California and add power to hurricanes forming in the Gulf of Mexico. Yet after 30 years of studying this cyclical weather pattern scientists are no closer to understanding how it works.

 That may be about to change. An international team of scientists will start a six-month data-gathering effort in the Indian Ocean in October to try and unravel the MJOs workings.  Feeding the Asia and Australian monsoon rains, the MJO surfaces every one to three months near the Maldives islands off the tip of India. As it journeys east, over Indonesia and beyond, the MJO can trigger rains and flooding on the west coast of North America and contribute to hurricanes in the north Pacific and Gulf of Mexico. It can even trigger the better-known El Niño-Southern Oscillation (ENSO), another cyclic weather pattern that forms in the tropics and influences weather worldwide but happens far less frequently.

Radar aimed at clouds are expected to reveal new information about the MJO. Credit: Mike Dixon, NCAR.

“We know basically why El Niño occurs every few years or so, and we understand the high and low pressure systems that traverse the US and other mid-latitude regions every few days,” said Adam Sobel, a scientist at Columbia University’s Lamont-Doherty Earth Observatory involved in the project. “The MJO is the most important phenomenon controlling weather fluctuations in the time scale range in between, but in comparison we understand it very little.”
The goal of the campaign, known as DYNAMO (Dynamics of the Madden-Julian Oscillation), is to help meteorologists improve long-range weather forecasts and seasonal outlooks. Most of the research will be coordinated from the Maldives, with instruments deployed on land, at sea and in the air.
Two planes, four ships and an array of balloon sounding units, moored buoys and meteorological radars will be used to gather data. The radar will allow scientists to peer inside cloud formations and see how rain storms develop and turn into an MJO. Oceanographers will also measure fluctuations in sea temperature and salinity as the weather pattern forms while a collection of ocean sensors, deployed from ships and moorings in the open sea, will measure ocean-atmosphere interactions.
“The ocean’s vast amount of heat and water plays an important role in shaping earth’s climate,” said Lamont-Doherty oceanographer Arnold Gordon, who with colleague Chris Zappa is involved in the project.  “The ocean obviously influences the MJO—this project will tell us how.”
The oscillation is currently captured very poorly in computer models used in weather and climate prediction. The field campaign is aimed at gathering observations that can improve the models, with an emphasis on clouds. “Although we don’t understand the MJO deeply, we know that convective clouds are essential to it,” said Sobel.  “Knowing how the convective clouds behave should help us understand the MJO better, and help us model ENSO and global climate response to increased greenhouse gas levels.” Sobel joins the field campaign in November while postdocs Daehyun Kim and Shuguang Wang travel there in October.

The National Center for Atmospheric Research (NCAR) is providing major observing facilities to the science team and helping to oversee the project’s operations and data management. Regular updates will be posted on the project's field catalog. The Lamont researchers will also be blogging about the MJO from the field.


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