FINGERPRINT OF OZONE DEPLETION IN THE SPATIAL AND TEMPORAL PATTERN OFRECENT LOWER-STRATOSPHERIC COOLING

OBSERVATIONS of air temperatures in the lower stratosphere from 1979 t o 1990 reveal a cooling trend that varies both spatially and seasonall y(1). The possible causes of this cooling include changes in concentra tions of ozone or of other greenhouse gases(2,3), and entirely natural variability, but the relative contributions of such causes are poorly constrained. Here we incorporate the observed decreases in stratosphe ric ozone concentrations(4) over the same period into a general circul ation model of the atmosphere, to investigate the role of the ozone lo sses in affecting patterns of temperature change. We find that the sim ulated latitudinal pattern of lower-stratospheric cooling for a given month through the decade corresponds well with the pattern of the obse rved decadal temperature changes, This result confirms the expectation , from simpler model studies(2,3,5), that the observed ozone depletion exerts a spatially and seasonally varying fingerprint in the decadal cooling of the lower stratosphere, with the influence of increases in concentrations of other greenhouse gases being relatively small. As an thropogenic halocarbon chemicals are important causes of stratospheric ozone depletion(2,3), our study suggests a human influence on the pat terns of temperature change in the lower stratosphere over this 11-yea r period.