Systematic changes of stratospheric temperature: relationship between the tropics and extratropics

Ozone declined over the extratropics of the Northern Hemisphere during the 1980s and 1990s. The interpretation of those systematic changes rests on the behavior of temperature, which declined simultaneously. New evidence reported here shows that systematic cooling of the wintertime stratosphere at high latitudes was accompanied by systematic warming at low latitudes. Those regions exhibit clear but opposing trends in the wintertime tendency of temperature, which is related directly to adiabatic warming and cooling. Mirrored by ozone, the compensating changes of temperature at high and low latitudes characterize a systematic weakening of the residual mean circulation, which regulates wintertime temperature and spring ozone.