Breakdown of the Polar Stratospheric Vortex

In early winter, cold temperatures result in the formation of a strong
circumpolar flow in the stratosphere, known as the polar night vortex,
producing favorable conditions for ozone depletion.

The breakdown of the Stratospheric Polar Night Vortex is an atmospheric event
that occurs once or twice each year in the polar wintertime stratosphere. As
the polar vortex is formed, sharp gradients of potential vorticity at the
vortex edge isolate polar air from the air at lower latitudes, producing
conditions favorable for wintertime polar ozone depletion. Rossby waves
propagating upward from the troposphere along the edge of the Polar Vortex
grows exponentially in amplitude, eventually tearing the vortex apart.The
animations depict the flow of the Polar Vortex by visualizing Potential
Vorticity (a variable that acts as a tracer) over the 16-day simulation. In the
second and succeeding images, the height of the data has been greatly
exaggerated to better show the rich vertical structure contained in the vortex.
In reality, the vortex is only a few tens of kilometers thick, a pancake-thin
region that can extend over much of the Northern Hemisphere.