Airborne observations of turbulence, mixing, and gravity waves in the tropopause region

In situ observations of small‐scale dynamics and compositional structure in the tropopause region are presented. The measurements were made aboard the Grob “Egrett” high‐altitude research aircraft above Aberystwyth, Wales, in the summer of 2000. The observations presented here show evidence of mixing of ozone and water vapor in a patch of intense turbulence just above the tropopause. This turbulence is shown to be the result of wind shear above a tropospheric jet stream. The value of the vertical eddy diffusion coefficient in this turbulence is estimated to be 0.9 m 2 s −1 . It is also shown that wavelike perturbations superimposed on the overall tracer structure can be accounted for by a gravity wave.