The Tropical Semiannual Oscillations in Temperature and Ozone as Observed by the MLS

Abstract

The first two years of MLS temperature and ozone data are used to examine the tropical upper-stratospheric SAO. Time series analysis revealed that the strongest amplitudes of the SAO occurred near the equator at 2 mb for temperature and 5 mb for ozone, consistent with previous observations. The first cycle of each calendar year was observed to have a much higher amplitude than the second cycle except for the warm phase in late 1991. Interannual variability in the strength of the SAO, such as the much stronger warm phase of late 1991 as compared to late 1992, was significant and could be partly attributed to the QBO in zonal wind.