Temperature Gradients in Stratospheric Turbulence

Abstract

Data obtained from U-2 HICAT flights were used to relate the magnitudes of horizontal temperature changes to flight conditions. The empirical findings can be used in estimating the effectiveness of aircraft-borne sensors which rely on temperature measurements for the remote detection of clear air turbulence. Gust velocity changes of at least 20 ft sec?1 occurred in all but one of 68 turbulence encounters in which temperature changes were 3C or higher, and in only 13 of 97 cases with changes of less than 1C. Although short-period temperature variations were generally small during smooth flight and increased in magnitude during rougher flight, exceptions were noted. Large horizontal temperature changes were observed during smooth flight in the vicinity of severe turbulence and during occasional flights where the temperature changed appreciably over shallow vertical layers. Small changes were sometimes noted during moderate turbulence when the vertical temperature structure was nearly isothermal.