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Eric Maloney
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Eric Maloney

Understanding the mysterious Madden-Julian Oscillation

by Alison Stevens (NOAA Modeling, Analysis, Predictions, and Projections Program)

From the front lawn of his childhood home in the Chicago suburbs, Eric Maloney, Professor at Colorado State University and NOAA-funded scientist, experienced extreme weather ranging from blizzards to severe thunderstorms. As a kid, he even videotaped a tornado. Maloney has been fascinated with the weather ever since.

Upper Atmosphere Graphic of Madden-Julian Oscillation

Upper Atmosphere Graphic of Madden-Julian Oscillation

The surface and upper-atmosphere structure of the MJO when the enhanced convective phase (thunderstorm cloud) is over the Indian Ocean and the suppressed convective phase is over the west-central Pacific Ocean. Source:

Maloney’s interest in climate and weather solidified as a physics major at the University of Illinois, where he connected with faculty in the Atmospheric Science department. In graduate school at the University of Washington, he studied Atmospheric Science and, after taking a pivotal tropical convection course, got hooked on a lesser-known atmospheric phenomenon called the Madden-Julian Oscillation (MJO). There he learned that the MJO could influence the weather he experienced as a kid, but scientists didn’t know why it behaved the way it did. From then on, Maloney knew he wanted to discover more about the mysterious MJO.  

The MJO is an eastward moving disturbance of clouds and rain near the equator that travels around the world every 30 to 60 days. It has increased and suppressed rain phases that produce opposite changes in weather patterns as the MJO moves across Earth. By altering the jet stream pattern (a channel of fast-moving air in the upper atmosphere that transports weather systems like storms), the MJO can strongly influence extreme events such as hurricanes, droughts, and heavy precipitation over the United States. However, climate models (which use mathematical equations to represent how the sun and different parts of the earth interact) have limited skill in representing the MJO compared to observations, so scientists like Maloney are trying to figure out why and how to improve the models.

Towards the end of graduate school, in March of 2000, Maloney and his co-author published significant findings in Science that received quite a bit of media attention. They found a relationship between the MJO and east Pacific and Atlantic hurricanes.

“We documented a four-fold increase in hurricane activity in the Gulf of Mexico and Caribbean Sea during certain phases of the MJO,” Maloney said. “The influence of the MJO on Gulf of Mexico hurricanes is important for people living along the U.S. Gulf Coast, because a large fraction of Gulf Coast hurricanes make landfall.” He explained that this relationship could help predict hurricane activity at least 2-3 weeks in advance.

Not only is the MJO associated with hurricanes, but it can also influence other extreme events such as cold spells and heat waves.

“If we can improve our simulations of the MJO, then we are going to be able to dramatically improve our predictions of extreme events over places like North America three to four weeks from now,” Maloney said. “But we still don’t have a great grasp on what makes the MJO tick.” Much MJO research has assessed whether scientists can make skillful predictions of the MJO. Very little work, however, has evaluated why they can or cannot.

Eric Maloney

Eric Maloney

Colorado State University Professor and NOAA-funded scientist

Maloney and his co-researchers are working to answer this question through their current research. His work on the MJO earned him the 2016 Atmospheric Sciences Ascent Award at the American Geophysical Union Fall Meeting. He is also chair of the NOAA Model Diagnostics Task Force, which is developing a framework to better diagnose climate and weather models. Much like how a doctor tries to diagnose why a patient doesn’t feel well, the task force tries to determine whether or not models produce good simulations, and if not, why they don’t.

Maloney’s specific piece of the task force is trying to diagnose models in the context of the MJO.

“The idea is to work closely with modeling centers to come up with a way to enable the modeling community outside of the centers […] to easily contribute their diagnostics,” Maloney said. “Then, modeling centers will be able to apply the diagnostics to their simulations to hopefully lead to fantastic modeling improvements in an accelerated fashion.”

Maloney feels optimistic about the improvements in MJO and other model simulations that this task force and similar efforts can achieve in the next 5-10 years. He thinks the modeling community is nearing a solution to understanding what makes the MJO “tick”, and consequently, making huge improvements in predictions of extreme events over the United States.

“Ultimately, 10 years down the line, I think that model diagnosis work and insight into understanding the MJO may be some of my most important contributions.”

Maloney is supported by the NOAA Modeling, Analysis, Predictions, and Projections (MAPP) Program. To learn more about his work as part of the NOAA MAPP Model Diagnostics Task Force, visit

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