The tropopause is affected by a variety of processes which in turn determine the distribution of trace species in the UTLS. The goal of our research is to constrain the abundance of trace species across the extratropical tropopause and to create a link between tracer abundance and dynamical processes. Our focus is on scales ranging from the planetary scale, Rossby wave dynamics, down to the sub-meso-scale, gravity wave dynamics and turbulence due to dynamic instabilities.
To constrain the abundance we conduct high frequency airborne in-situ measurements on board different research aircrafts (HALO, LearJet, Falcon). We measure trace gases with different atmospheric lifetimes, among others nitrous oxide (N2O), carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4), which allow us to identify cross tropopause exchange and to attribute air masses to different source regions. In recent years we, therefore, partly organized and fully participated in several measurement field campaigns around world (e.g., Central, Northern, and Western Europe, New Zealand). The next campaign is planned for summer/autumn 2019 in South America.
We further use numerical tools to explain the tracer distributions and to link the measurements to dynamical processes on the various scales. For this we use forecast, analysis, and reanalysis data from numerical weather prediction (NWP) models, e.g., from ECMWF, as well as products from chemistry climate models (CCM), e.g., EMAC, MECO(n). Furthermore, we apply Lagrangian diagnostics to identify source regions of the measured air masses and to diagnose their fate in the atmosphere. Furthermore, we conduct numerical simulations with model setups ranging from highly idealized to fully realistic on regional and global scales. For this we use state-of-the-art models such as COSMO or ICON.