Wintertime climatology of MOZAIC ozone based on the potential vorticity and ozone analogy

A climatology is compiled of wintertime ozone measured by MOZAIC aircraft. It spans the winters of 1994/1995 to 1997/1998. It is generated employing and in the process confirming the analogy between potential vorticity and ozone. The methodology consists of interpolating equivalent latitude derived from analyzed potential vorticity onto flight tracks of the aircraft. In a second step the measurements are cast into a gridded form; this generates seasonal synopses of ozone in the coordinate space spanned by time, potential temperature, and equivalent latitude. At low equivalent latitudes the irregular appearance of high‐ozone transients in combination with the relatively small measurement density renders a determination of seasonal‐mean ozone problematic. However, in middle and high equivalent latitudes of the Northern Hemisphere ozone mixing ratios are well summarized by stating seasonal means and seasonal increases only. The results derived for the four winters exhibit some marked interannual variability. The method allows the determination of “expected” ozone along the flight tracks from the gridded ozone. A comparison with measured ozone for two selected periods of time suggests that discrepancies between expected and measured ozone hint at the presence of filamentary structure in the ozone field and associated stratosphere‐troposphere exchange. In the four‐winter mean such “outliers” of measured ozone occur most frequently in the vicinity of the North Atlantic storm track, corroborating earlier studies on filamentation activity.