Speaker
Description
The composition of the upper troposphere / lower tratosphere (UTLS) is affected by the Brewer Dobson Circulation (BDC) as well transport across the tropopause and the jets. Since these dynamical processes involve the coupling of transport and mixing processes on very different temporal and spatial scales, long-term changes or even mean distributions from observational data sets on the distribution of tracers in the UTLS are therefore difficult to detect. Complications arise particularly from the short term variability of the tropopause and jet locations, which introduce variability in tracer distributions, especially for those with strong gradients at the tropopause. Therefore it is essential to account for the dynamically induced variability by, e.g., the tropopause location when looking at trends in dynamical processes such as stratosphere-to-troposphere exchange (STE) or the BDC and assessing their effects on trace gas distributions and long-term changes. The relationship of tracer distributions to the tropopause and jet locations as given in reanalysis data thus plays a key role in accounting for the variability and in the interpretation of tracer distributions.
OCTAV-UTLS (Observed Composition Trends And Variability in the UTLS) will use different observational data sets from soundings, lidar, aircraft and satellite to investigate the effect of dynamical variability on the ozone distributions. This is done by remapping of observations in different jet or tropopause based coordinates with the JETPAC-tool (Jet and Tropopause Products for Analysis and Characterization) using MERRA-2 reanalysis data. Some examples of the method are shown demonstrating the effect on the distribution and a reduction of variability.
