WAVE-WAVE INTERACTIONS IN THE STRATOSPHERE: OBSERVATIONS DURING QUIET AND ACTIVE WINTERTIME PERIODS.

Abstract

Using satellite data from the Nimbus 7 LIMS instrument, a previous study by A. K. Smith showed that interactions among planetary waves 1, 2 and 3 in the stratosphere were significant during January 1979. That month was characterized by an exceptionally large wave 1 amplitude in the stratosphere. The present study extends the analysis to the period November 1978-March 1979 to determine the conditions under which wave-wave interactions have a significant effect on variation in wave activity and on wave-mean flow interactions. A quantitative measure of how wave-wave interactions affect the wave activity of zonal waves 1 and 2 is obtained from the potential enstrophy budget. The results demonstrate that the relative importance of wave-wave versus wave-mean flow interactions depends on the magnitude of the eddy mean wind and potential vorticity relative to the zonal means.