Layering Occurrence and Characteristics in Ozonesonde Profiles in the Upper Troposphere/Lower Stratosphere Region

Vertical profiles, as observed in ozonesonde data, display instances of both well-mixed and layered environments. Layers can develop as a consequence of a number of transport processes, including detrainment, tropopause folding, and wave breaking. We have developed and used a layer identification method that does not rely on filtering or on use of a default ozone distribution. We will present results on the occurrence of layers, specifically their frequency and vertical distribution. This will include a breakout using established criteria in ozone variation, water vapor and static stability, and their co-variation with respect to ozone. The contribution of layering to the overall ozone variability will be noted. This and related factors will be detailed as a function of height and also of height relative to the thermal tropopause (WMO criterion). The relationship between the thickness (extent in height) of layers and their amplitude (ozone increment) will be discussed. The underestimation of peak ozone values and corresponding overestimation of minimum ozone values in layers caused by the moderate time response of the ozonesonde instrument as it ascends through the profile can be approximated using this relationship by taking account of the rise rate. The impact of this effect on estimates of the variability of lower stratospheric ozone will be discussed. The ozone profile data used cover a period of several years and are from sites around the United States.