Kelvin wave variability in the upper stratosphere observed in SBUV ozone data

Abstract

The eight years of SBUV data reveal the regular occurrence of eastward-propagating zonal wave 1-2 Kelven waves with periods in the range of 5-15 days. These data show a strong semiannual modulation of Kelvin wave activity, as documented previously in rocketsonde observations. Eight-year-average ensemble spectra are compared to the semiannual oscillation (SAO) in stratospheric zonal winds; a seasonal asymmetry in the strength of Kelvin waves is found, which mimics that observed in the zonal winds. There is a near exact phasing of maxima in wave variance with the strongest easterly zonal winds, ie, when the wind acceleration is near zero; this argues that Kelvin waves are not a determining factor in the westerly acceleration phase. No consistent relationship with the quasi-biennial oscillation (QBO) in the lower stratosphere is observed, and correlations with upper stratospheric winds are weak or nonexistent. -from Authors