Impact of the Stratospheric Warming 2012 / 2013 on the Middle Atmosphere

Abstract:

The effects of stratospheric warming events are not restricted to the stratosphere only. There is considerable impact on the mesosphere.

Global ozone and temperature data derived from the METOP-A-GOME-2 and TIMED-SABER satellites, respectively, and rotational temperatures obtained by ground-based infrared airglow spectrometer measurements (GRIPS) including polar stations within the Network for Mesospheric Change, NDMC, are analyzed in order to characterize both larger scale (planetary waves) and smaller scale (gravity waves) atmospheric dynamics during minor and major stratospheric warming events which took place in winter 2012/2013 in the Northern Hemisphere.

The planetary wave regime is found being dominated by zonal wavenumbers 1 and 2 which significantly trigger the observed stratwarming; induced momentum on the background zonal flow due to wave breaking is estimated. As a consequence of the stratwarming the planetary wave number 3 is found being modified significantly in its wave characteristics (phase speed, frequency).

Impact of the stratwarming on the upper mesosphere / lower thermosphere is discussed. Evidence for some mesospheric cooling prior to the stratwarming is found. Gravity wave characteristics in that altitude regime seem to be altered. There is also evidence that the mesopause airglow layer might have changed its geometric height during these events.