Press Conference 2 Polar Ozone – What's going on in the Arctic? by EGU2011
Assigning causality between the polar vortex and cold stratospheric temperatures is simplistic and incorrect.
Darkness over the pole in winter lowers the stratospheric temperatures. The colder stratospheric temperatures initiate the formation of the polar vortex in the upper stratosphere which then extends lower into the atmosphere as it forms throughout the winter. The vortex can then reinforce colder temperatures by isolating the air mass.
This does not explain the progressively colder stratospheric temperatures. This must be attributed to the increase in greenhouse gasses which insulate the stratosphere from radiating heat from the surface, increasing the differential at the tropopause.
Water vapor in the colder stratosphere below -70 C forms polar stratospheric clouds which through chemical reactions degrade the ozone layer.
The primary way that water vapor enters the stratosphere is through the breakdown of methane in the stratosphere into water vapor and CO2.
The polar vortex enhances the transport of methane into the stratosphere.
Transport of methane in the stratosphere associated with the breakdown of the Antarctic polar vortex
High concentrations of methane observed inside the vortex show mixing of lower-latitude air into the vortex. An RDF calculation confirms the behavior of methane transport into the vortex.