The 4‐day wave in the Antarctic mesosphere

A zonal wave number one eastward propagating planetary wave observed in the high latitude winter stratosphere with a period near 4 days has been studied by a number of previous authors. Radar observations coupled with stratospheric analyses are here used to demonstrate that this wave, known as the 4‐day wave, extends into the Antarctic upper mesosphere. Previous workers have asserted that the wave is a manifestation of the observation of warm pools rotating in the polar vortex, and that the pool seems to behave in a quasi‐nondispersive manner. The observation of the 4‐day wave in the upper mesosophere presented here appears to validate previous claims that the warm pools are being maintained by wavelike dynamics, rather than simple advection.