Observational study of the 4-day wave in the mesosphere preceding the sudden stratospheric warming events during 1995 and 2002

Comparisons of stratospheric and mesospheric temperatures at the South Pole during the 1995 and 2002 observing seasons show evidence of mesospheric cooling preceding the SSW events.

Spectral analyses of South Pole OH air glow brightness measurements from the 1995 and 2002 observing season and NCEP stratospheric temperatures show amplification of the 4-day wave planetary wave before the start of the mesospheric cooling trend, the latter preceding the onset of SSW event. A similar behavior of planetary wave is also seen in the stratosphere where the 4-day wave is seen to grow in amplitude just before the peak of the sudden increase in temperatures.