Clear Air Turbulence analysis using isentropic methods.

Abstract

Isentropic analyses were completed subjectively and by the Petersen (1986) objective analysis scheme for a 24-h Clear Air Turbulence (CAT) outbreak over the midwest United States. The purpose of the study is to determine if areas of high CAT potential could be identified by subjective isentropic analyses, and then by the automated analyses produced by the Petersen objective analyses. A background of CAT theory and current CAT forecasting techniques are also presented. The synoptic situation indicates the importance of the jet stream structure in this case. The study reveals that analyzed areas of low Ri and high wind shear correspond very well to reports of CAT. The objective analysis performance is fair overall. It shows a distinctive weakness in the analysis of the wind speed, occasionally producing spurious wind maxima. Analyses of the mass field, frontal slope and Montgomery stream function, are quite successful