Coherent variations of monthly mean total ozone and lower stratospheric temperature

Abstract

Space‐time patterns of correlation between total ozone and lower stratospheric temperature are documented, based on 14 years (1979–1992) of global monthly mean observations. Data are obtained from the total ozone mapping spectrometer (TOMS) and microwave sounding unit (MSU) channel 4, the latter being a weighted mean temperature of the 150‐ to 50‐mbar layer. These data are analyzed (separately) for linear trend, solar cycle, quasi‐biennial oscillation (QBO), and El Niño‐Southern Oscillation (ENSO) variations via linear regression: significant signals are identified for each term, and the corresponding structures in ozone and temperature are found to be highly coherent. The temperature trends derived here show significant cooling of the lower stratosphere over Northern Hemisphere (NH) midlatitudes in winter‐spring and over Antartica in Southern Hemisphere (SH) spring; the overall space‐time patterns are similar to those determined for ozone trends. Interestingly, temperatures do not decrease over SH midlatitudes during midwinter, in spite of large ozone losses. These data furthermore show globally coherent ozone and temperature perturbations associated with both QBO and ENSO variations; a new result here shows large total ozone anomalies in middle‐to‐high latitudes of both hemispheres associated with ENSO events. Residuals from the ozone and temperature time series (defined as the deseasonalized total minus the regression fits) show strong positive correlation in middle‐to‐high latitudes but weak correlations in the tropics. Time periods following the volcanic eruptions of El Chichon and Pinatubo are clearly identified from the coupled signatures of decreased ozone and increased temperature, opposite to the positive ozone‐temperature correlations observed at other times. The ratios of ozone to temperature anomalies derived here show quantitative signatures indicating that either radiative (trend, solar, and QBO) or dynamical (ENSO and residuals) processes are responsible for the strong ozone‐temperature correlations.