Principal modes of the total ozone on the Southern Oscillation timescale and related temperature variations

Abstract

Total ozone and associated temperature variations on the Southern Oscillation timescale have been investigated using monthly total ozone mapping spectrometer and temperature data for the latitudinal domain between 70°N and 70°S and from 1979 to 1991. The first two modes for total ozone describe the anomalous total ozone patterns associated with the extremes in the Southern Oscillation. The first mode has the largest loadings in the southern hemisphere (SH) subtropics and midlatitudes with an east-west dipole in antiphase with a tropical east-west dipole. The second mode has its largest loadings in the tropics with an east-west dipolar pattern. These modes are intimately related to variations in the mean temperature in the lower stratosphere, and this relation is such that the total ozone and mean temperature anomalies are positively correlated. The tropospheric temperature patterns are confined in the tropics, where temperature and total ozone anomalies are negatively correlated. The tropical temperature and total ozone variations are driven by modulations in the tropical convection associated with the Southern Oscillation. The Southern Oscillation signals in the stratospheric temperature and in the total ozone are strongest in the SH midlatitudes during the winter-spring period and precede the extremes in the Southern Oscillation Index (SOI) by a few months. Thus the total ozone index, defined similarly to the SOI, seems to be more appropriate than the SOI to monitor the stratospheric temperature in the extratropics, in particular in the SH middle to high latitudes.