OCCURRENCE OF OZONE LAMINAE NEAR THE BOUNDARY OF THE STRATOSPHERIC POLAR VORTEX

Analysis of ozonesonde data collected at high northern latitudes in winter and spring shows that laminae of enhanced and depleted ozone are associated with the polar vortex. In January and February, they are most common at all latitudes in the potential temperature range 370-430 K, but are abundant up to 500 K between 60-degrees and 70-degrees-N. In March and April they occur most frequently northward of 75 N, and are abundant up to 520 K, whereas they are largely confined to the range 320-440 K at lower latitudes. Analysis of data gathered during the Airborne Arctic Stratospheric Expedition (AASE) in 1989 confirms that laminae are confined below 420 K in January and February when the 400K potential vorticity exceeds 15 muK kg-1 m2 s-1, i.e., the polar vortex boundary. Further analysis of ozone lidar data obtained during AASE depicts clearly the extrusion of laminae of enhanced ozone concentration from the polar regions in the altitude range 13-15 km. These extrusions form a class of laminae which transport ozone equatorward in the lowest levels of the stratosphere. Possible dynamical mechanisms for these laminae are discussed.