Recent Rocketsonde-Derived Temperature Variations in the Western Hemisphere

Abstract

Rocketsonde-derived temperature variations within north polar, north subtropical and equatorial zones of the western hemisphere are examined for height layers of 26–35, 36–45 and 46–55 km for the years 1965–76, inclusive. As a comparison, radiosonde-derived temperature variations are examined for the surface to 16 km and 16–24 km layers for the same hemisphere and zones. The rocketsonde data suggest, in general, a warming in middle and upper stratosphere prior to 1970, and a somewhat larger (up to 5°C) cooling thereafter, yielding a temperature variation basically in phase with sunspot number, but the radiosonde data for the low stratosphere do not indicate such a variation. While this discrepancy raises questions concerning the representativeness of either or both sets of data, model findings do suggest that any warming resulting from enhanced ultraviolet radiation at sunspot maximum would be an order of magnitude greater in the middle and high stratosphere than in the low stratosphere. A quasi-biennial oscillation in temperature clearly extends at least up to the stratopause (50 km) in equatorial and subtropical zones, with a maximum amplitude (with the given smoothing) of about 1°C near 30 or 40 km, and a phase shift with height twice as large in the equatorial zone as in the subtropics.