An Unusual Train of Waves in the Southern Hemisphere Stratosphere

The animation above, taken from a 10-day forecast initialized on 16 September, 2019, reveals wave breaking on two scales. The global scale that deforms the polar vortex (darkest color) and moves air from the tropics (green and yellow) to the pole, and a wave of smaller scale vortices that mix tropical and high latitude air near 25°S. The high latitude air near 25°S originated from near the edge of the polar vortex and was stripped off the vortex earlier as described above. Typically, in the Northern Hemisphere, the air stripped from the vortex edge rolls up into one or two independent, smaller vortices. Here, however, a wave structure consisting of a chain of six smaller vortices has formed, and these appear to reinforce each other as a coherent wave. Such behavior has not been noted, previously. Read More.