On the formation of ozone laminae at the edge of the Arctic polar vortex

Ozone vertical profiles commonly display thin‐layered structures, or laminae, in the lower stratosphere of the extratropics, predominantly during winter and spring. the mechanism for their formation is still uncertain. In this study, high‐resolution isentropic transport of a passive tracer on synoptic time‐scales is performed with an off‐line transport model, which is forced by winds derived from global meteorological analyses or forecasts. the study focuses on a meteorological situation which occurred in late January 1992. On isentropic surfaces, the tracer distribution, initialized as the analysed potential vorticity, is eroded into filamentary structures in the mid‐latitude surf‐zone. Repeated poleward intrusions of mid‐latitude air are shown to lead to the formation of convoluted filamentary structures at high latitudes. By performing isentropic advection on many closely spaced independent levels, the vertical structure of these tracer filaments can be studied. They are shown to be part of tracer sheets which are vertically tilted in the shear zone in the vicinity of the polar jet. Thin laminar structures in the tracer vertical profiles appear as the result of isentropic wrapping and vertical shearing of such tracer sheets. A comparison is made with ozone laminae, found in balloon‐borne soundings during the European Arctic Stratospheric Ozone Experiment.