Research team must first observe new equatorial wind patterns in Antarctica

A CIRES leadership team has discovered a critical link between wind at the Earth’s equator and atmospheric waves 6,000 miles away at the South Pole. The team has for the first time found evidence of a Quasi-Biennial Oscillation (QBO) – an atmospheric circulation pattern created at the equator – in McMurdo, Antarctica.

The discovery highlights how winds in the deep tropics affect the distance of the South Pole, particularly the Arctic Circle, which can trigger outbreaks of cold weather patterns at medium latitudes. Scientists will be able to use this information to better understand the planet’s weather and climate patterns and to burn more accurate atmospheric models, the authors say.

“We have now seen how this atmospheric pattern propagates from the equator to the high latitudes of Antarctica, showing how these distant regions can be connected in ways we did not know before,” said Zimu Li, a former CIRES research assistant who did this work at the University of Colorado Boulder, and lead author of the study published today in the Journal of Geophysical Research: Atmospheres.

“This can improve our understanding of how large-scale atmospheric circulation works, and how patterns can ripple in one area of ​​the world around the world,” said Xinzhao Chu, CIRES Fellow, Professor at Ann & HJ Smead Department of Aerospace Engineering Sciences at the University of Colorado Boulder, and corresponding author on the new work.

Every two years or so, the QBO causes the stratospheric winds at the Earth’s equator to change direction, varying between east and west. Lynn Harvey, a researcher at CU’s Laboratory for Atmospheric and Space Physics (LASP) and a research fellow, helped the team study the polar vortices, the massive eddies of cold air that spiral across each of Earth’s poles. . The study reports that the Antarctic vortex is expanding in the eastern phase of the QBO and contracting in the western phase. The team suspects that when the QBO changes the behavior of polar vortex, which in turn influences the behavior of atmospheric waves, called gravitational waves, which travel across different layers of the atmosphere. They identified specific types of changes in those gravitational waves: The waves are stronger in the eastern period of the QBO and weaker than the QBO is western.

For the past nine years, members of Chu’s lidar team have spent long seasons at McMurdo Station, Antarctica, braving 24-hour darkness and fresh temperatures to operate custom lasers and measure patterns in the Earth’s atmosphere. These long-term measurements, along with 21 years of NASA MERRA-2 atmospheric records, were critical to the new findings. Each QBO cycle takes years to complete, so long-term data streams are the only way to identify interannual connections and patterns.

“Atmospheric scientists can use this information to refine their models – before this nobody really knew how QBO affects gravitational waves in this polar region,” said Xian Lu, a Clemson University researcher and co-author on the study. “Researchers can use this information to model and predict climate, including the variability of atmosphere and space and long-term change.”