Features of SAO in ozone and temperature over tropical stratosphere by wavelet analysis

Abstract

Spatiotemporal variation of Semi-Annual Oscillation (SAO) in temperature and ozone over the tropical-subtropical belts (40° N-40°S) was studied using Microwave Limb Sounder data for the period 1992-1999. Wavelet analysis followed by cross-wavelet analysis was performed to study interannual variations in amplitude and phases of SAO and to determine the definite relationship between them. Latitude-height cross-sections of amplitudes of temperature and ozone SAO exhibit a peak near the Equator. The peak in amplitude of temperature SAO is at a higher altitude (ca 2 hPa) than that in ozone SAO (ca 6 hPa). The peak in amplitude of ozone SAO is almost symmetrical around the Equator but, in temperature SAO, it is asymmetrical around the Equator. The phase structure reveals that the temperature SAO descends faster than the ozone SAO. Cross-wavelet analysis shows an antiphase relation between the amplitude of the temperature and ozone SAO in the upper stratospheric region, whereas an in-phase relation exists in the lower stratospheric region.