Public Release: 

PNNL talks weather phenomena at AGU

PNNL to share research at world's largest geophysical science meeting

DOE/Pacific Northwest National Laboratory

SAN FRANCISCO -- Scientists from the Department of Energy's Pacific Northwest National Laboratory will talk about tropical weather, carbon cycle, climate, and more at the 2015 American Geophysical Union Fall Meeting, which runs Monday, Dec. 14 through Friday, Dec. 18 at the Moscone Convention Center in San Francisco.

Day and night conspire to stall rainy weather

March's Tropical Cyclone Pam was one of the most intense cyclones ever, causing widespread damage on the island nation of Vanuatu. Such cyclones often arise from the weather phenomenon known as the Madden-Julian Oscillation. The MJO travels eastward from the Indian Ocean to the Pacific over the collection of islands that make up the Maritime Continent -- Sumatra, Borneo, the Philippines and Papua New Guinea. PNNL researchers explored the forces that push this weather event along and what stalls it as it crosses the islands. The team used data collected in Papua New Guinea in computer simulations to test how the daily pulses of clouds over these islands affect the MJO's movement.

Clouds form in the afternoon as the sun warms up the day. Then temperatures fall and clouds dissipate. When the team got rid of the daytime clouds by replacing the day-night cycle of solar heat with the average amount of heat over that time, the simulated MJO sailed along from the Indian Ocean to the Pacific. However, with the daily heating cycle in place, the MJO stalled over Sumatra and Borneo, falling as rain over the islands. PNNL's Samson Hagos will discuss how these daily pulses of cloudiness can trap heat over the islands, causing convection that hampers MJO's eastward progress.

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Support and data collection for this work came from the Department of Energy and DOE's Atmospheric Radiation Measurement Climate Research Facility.

Tuesday, Dec. 15, 11:50 a.m. - 12:05 p.m., Moscone West, 3008, A22E-07, Samson Hagos, "The impact of diurnal cycle over the Maritime Continent on the Madden-Julian Oscillation." https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/62874

Interdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. Founded in 1965, PNNL employs 4,400 staff and has an annual budget of nearly $1 billion. It is managed by Battelle for the U.S. Department of Energy's Office of Science. As the single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information on PNNL, visit the PNNL News Center, or follow PNNL on Facebook, Google+, LinkedIn and Twitter.

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