Understanding Satellite, Aircraft, Balloon, and Ground-Based Ozone Variability: Using Dynamical Coordinates for Consistent Analysis of UTLS Composition

The ozone composition trends in the upper troposphere/lower stratosphere (UTLS) are still highly uncertain due to sharp spatial gradients and large variability caused by competing transport, chemical, and mixing processes near the upper tropospheric jets and extra-tropical tropopause, as well as due to inhomogeneous, spatially and temporally limited observations of the region. One goal of the Observed Composition Trends And Variability in the UTLS (OCTAV-UTLS) SPARC activity is to analyse long-term trends in ozone from several measurement platforms, focusing on those with decadal or longer records. These include satellite observations from Aura-MLS and ACE-FTS, as well as high resolution measurements from aircraft (including CARIBIC-2 and various research campaigns) and from ground- and balloon-based observations (lidar and sondes).

Jets and the tropopause acts as transport barriers, representing boundaries between atmospheric regimes controlled by different processes; they can thus be used to separate data taken in those different regimes before assessing trends. Various dynamical coordinates, especially related to jet or tropopause locations can be used to account for the spatial and temporal variability of transport barriers. Here we test the ability of several coordinate systems to segregate air in different atmospheric regimes. A comprehensive dynamical dataset derived from a single reanalysis for all measurements allows us to reference each measurement to the location of jets and tropopauses in different coordinates (e.g., altitude, pressure, potential temperature, equivalent latitude). We assess of which dynamical coordinate combinations are most useful in minimizing artificial variability induced by mixing measurements taken in different regimes.