New research published in the Journal of Geophysical Research: Atmospheres reports the discovery of equatorial winds at the South Pole in McMurdo, Antarctica – some 6,000 miles away from their origin. This is the first time that a Quasi-Biennial Oscillation (QBO) -- an atmospheric circulation pattern that stems from the equator – has been documented so far south.
"This can better our understanding of how large-scale atmospheric circulation works, and how patterns in one area of the world can ripple across the entire globe," said corresponding author Xinzhao Chu, a CIRES Fellow and professor in the Ann & H.J. Smead Department of Aerospace Engineering Sciences at the University of Colorado Boulder.
This finding provides evidence for the link between the tropics and the South Pole, demonstrating the very real atmospheric connection in the polar vortex. While we have known that the stratospheric winds at Earth's equator to change between easterly and westerly directions approximately every two years by cause of the QBO, this finding helps paint a clearer picture of the polar vortices over Earth’s poles.
"We have now seen how this atmospheric pattern propagates from the equator all the way to the high latitudes of Antarctica, showing how these far-away regions can be linked in ways we didn't know about before," said lead author Zimu Li, a former CIRES research assistant who did this work at the University of Colorado Boulder.
After years of collecting data at McMurdo Station, Li and Chu, along with their colleagues, have been able to show that the Antarctic vortex expands during the QBO easterly phase and contracts during the westerly phase. They say that this expanding and contracting behavior triggers changes in atmospheric waves called gravity waves, making them stronger during the easterly period of the QBO and weaker when the QBO is westerly.
Thanks to the team’s determination and persistence, they now have enough data to apply their findings to enhance atmospheric models that track the planet's weather and climate patterns.
"Atmospheric scientists can use this information to improve their models -- before this nobody really knew how QBO impacts gravity waves in this polar region," said co-author Xian Lu, a researcher at Clemson University. "Researchers can use this information to better model and predict climate, including the variability of atmosphere and space and long-term change."