A Statistical Analysis of Wind and Temperature Variables Associated with High Altitude Clear Air Turbulence (HICAT)

Abstract

Chi-square and Kolmogorov-Smirnov statistical tests are applied to distributions of wind and temperature variables measured in conjunction with Project HICAT U-2 flights from worldwide locations. A distinction is made between turbulent and nonturbulent situations. Turbulence is found to occur in layers that exhibit either large decreases in temperature with height or strong vertical wind shears. Turbulent outnumbered nonturbulent cases nearly 4 to 1 for Richardson numbers <15. A high correlation exists between the magnitudes of in-flight measured temperature variations and the sum of the gust velocity components. Examples of time histories show that the high correlation does not reflect complexities of the temperature change for individual turbulence encounters.