Dynamics of the Madden-Julian Oscillation (DYNAMO)

Prof. Adam Sobel and Dr. Shuguang Wang (APAM), along with Dr. Daehyun Kim (LDEO) and colleagues from Colorado State University and Harvard University, were part of an international team of scientists who participated in a 6-month data-gathering effort in the Indian Ocean to try and unravel the workings of the Madden-Julian Oscillation.


By Adam Sobel

The Madden-Julian Oscillation (MJO) is a natural fluctuation of the weather in the tropics. On a time scale of 30-60 days, the MJO causes the weather to alternate between a rainy regime with westerly (west to east) winds, and a drier regime with easterly winds. Each regime covers thousands of km in the east-west direction, and the changes progress slowly from west to east. The MJO most strongly affects the weather over the tropical Indian and western Pacific oceans and the tropical land masses adjacent to them, but also influences places far from there including higher latitudes (even New York). Despite several decades of study, we don’t understand the basic physics of the MJO – what makes it happen at all? It’s a major outstanding problem in atmospheric and climate science.

In the fall of 2011-2012, there was a large multinational field campaign in the Indian ocean to study the MJO, called Dynamics of the Madden-Julian Oscillation (DYNAMO). The location was the tropical Indian ocean, with most people on two island bases - Addu Atoll in the Maldives, and Diego Garcia – and two ships. Observations were taken by radars, radiosondes (aka weather balloons) and many other instruments based on the islands, the ships, and two aircrafts.

I participated in DYNAMO, along with two postdocs here at Columbia, Shuguang Wang and Daehyun Kim, as well as colleagues Zhiming Kuang (Harvard) and Eric Maloney (Colorado State). Each of us spent 2-3 weeks on Gan island. As members of the modeling team for DYNAMO, our real job in the project was to do computer simulations, not make measurements. As such we didn’t have to go in the field, and most modelers don’t. I knew from previous field experiments, though, that one learns a great deal by going. I encouraged everyone from our team to go, and they eagerly did. We phased our visits in sequence so that one of us was there for most of the intensive phase, October-November 2011. We spent our days looking at all the data coming in, and doing our best to make ourselves useful to the scientists operating the instruments.

The experiment went phenomenally well. The atmosphere cooperated, providing several strong MJO events in rapid succession. There were no major instrument failures. A huge amount of data was gathered, and will be analyzed for years now. For our group, it was a chance to see first hand the atmospheric phenomenon we have studied for years on the computer. The Maldives is also a wonderful place to visit.  

The only dark part of the story came near the end of the experiment, after all of our own group was long gone but a skeleton crew remained gathering a few last observations. In February, the first democratic government of the Maldives was overthrown in a coup by a faction representing the previous government. This brought an end to the experiment, and brought turmoil to this small island nation.

Read the blog:
maddenjulianconversation.blogspot.com

LDEO: Investigating a Tropical Weather Pattern with Global Reach
www.ldeo.columbia.edu/news-events/investigating-tropical-weather-pattern-global-reach  

NCAR AtmosNews Feature
Between weather and climate: Seeking long-range forecast clues from the Indian Ocean

www2.ucar.edu/atmosnews/features/6356/between-weather-and-climate


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