Analysis of clear air turbulence near the jet stream

Abstract

Flights of ‘Project Jet Stream’ (1956–1957) have been analyzed with respect to various meteorological parameters and clear air turbulence near the jet stream in order to find a method for the prediction of high-level turbulence in the atmosphere. It is found that the horizontal velocity convergence has a pronounced effect on turbulence in the atmosphere. The percentage of turbulence occurrence and the turbulence intensity generally increase with increasing horizontal velocity convergence and may be approximated by an exponential function of the latter. An analysis is also made of the distribution of turbulence in the vicinity of the jet stream and the effect of jet stream curvature on high-level turbulence. It is found that (1) the percentage of turbulence occurrence is higher to the north than to the south of the jet and the percentage of turbulence occurrence is greater below the jet core than above it and (2) curved jets have a higher percentage of turbulence distribution than straight jets and the straight segment east of a cyclonic jet has a higher percentage of turbulence occurrence than the straight segment west of it.