In situ measurements of trace gases, winds and temperature from the WB-57F airborne platform are used to investigate mixing and stratosphere-troposphere exchange in the region of the subtropical jet. The high resolution and precision of these measurements allow mixing to be examined on a wide range of spatial scales. Scaling analysis is used to determine the dominant scales of variability and where the variability occurs in relation to the jet. We also examine the strength of the mixing ‘barrier’ produced by the jet which inhibits quasi-isentropic stratosphere-troposphere exchange. Tracer gradients across the jet during different seasons are compiled and compared to previous studies.