Project B08:
Lagrangian analysis of the role of extratropical cyclones for UTLS aerosol and humidity

Brief Summary

Extratropical cyclones are linked with organised, large-scale ascent that transport water vapour, trace gases, and aerosol particles to the UTLS. While the role of warm-conveyor belts (WCBs) is undebated, a quantification of their contribution to the extratropical UTLS composition is not available. Cloud and precipitation formation strongly modify transported water vapour and aerosol content during the ascent. The importance of different processes, the impact of the uncertainties associated with their representation in numerical models are not well understood, but are likely import for investigating the impact of WCBs on future UTLS composition.
The objective of this project is to develop a comprehensive understanding of the impact of WCBs on the composition of the extratropical UTLS. We will utilise high-resolution simulations and Lagrangian analysis methods to investigate the detailed moisture and aerosol budget along the ascent and to separate slantwise and embedded convective ascent. Perturbed parameter ensembles of two case studies are used to characterise the uncertainty of outflow moisture content and structure to parameter choices in the cloud microphysics. Combining these ensemble simulations with observational data from the DLR Falcon and enviscope Learjet campaigns conducted within this CRC will provide insight into the key processes controlling the transport and allow us to explore constraints on the model representations. The process-oriented, case-study based analysis will be complemented by novel high-resolution ensemble simulations, that explicitly link the individual ensemble members to their climatological significance. With this approach a climatology of WCB outflow properties and the role of convective and slantwise ascent is established from high-resolution simulations. The model climatology will be evaluated with long-term observational data from IAGOS and satellite observations. Finally, the impact of climate change on WCB moisture transport will be explored with the same approach and the results will be compared to global climate model simulations.

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