Project B08:
Lagrangian analysis of moisture, aerosols, trace gases and water isotope distribution in the extra-tropical UTLS

Brief Summary

Radiatively active substances, including water vapor, clouds, aerosols, and trace gases, in the UTLS region are known to substantially influence the current climate state and future changes thereof. In Phase I, we have focused on water vapor transport to the UTLS in warm-conveyor belts (WCB): we have for the first time quantified the contribution of WCB to the extra-tropical UTLS based on ERA5 reanalysis data as well as developed and applied diagnostics for water-vapor transport in WCBs including the role of embedded convection. Furthermore, we have investigated the role of cirrus in the extra-tropical transition layer in shaping the UTLS thermodynamics structure.

Recent analysis of the TPex measurements and other observational datasets show a large variability of UTLS aerosol and moisture structure at annual, seasonal, and synoptic timescale. The processes and flow configurations controlling the emergence of these structures is only partially understood.

In Phase II, we will therefore
(i) systematically quantify the variability of UTLS moisture structure,
(ii) investigate the processes that result in the different UTLS moisture structures, and
(iii) expand our diagnostics from Phase I to other trace constituents, in particular aerosols and water isotopes.

The variability of UTLS moisture structure will be quantified by analyzing existing observational data, in particular high-resolution radiosonde data, with advanced statistical methods. On this basis we will select archetypical scenarios (also considering availability of detailed observational data from TPex-I/II, NAWDIC), which will then be investigated in detail with high-resolution ICON simulations including our Lagrangian diagnostics. Further, starting with a WCB scenario, we will  investigate the role of vertical transport for UTLS aerosol composition by utilizing ICON-MESSY aerosol and chemistry modules. In addition, we will explore potential signatures in water isotopes with offline box-model simulations along our high-resolution ICON-based trajectories. Aerosol and water isotope signatures will be compared to observational data from airborne platforms (e.g. TPex-I/II, NAWDIC) and satellite, where possible.

By considering the combination of different trace constituents we may identify fingerprints of different processes and air mass sources that can be used to more vigorously combine observations and models and provide effective, processes-oriented evaluation options for the models.

Project Poster

Evaluation Poster Phase I in 2025

Members