Examining the extra-tropical upper troposphere and lower stratosphere using remote sensing limb-sounder measurements of unprecedented vertical resolution

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Trace gas exchange between troposphere and stratosphere greatly contributes to upper troposphere and lower stratosphere (UTLS) composition changes and variability, which are major drivers of surface climate change. This points to the need of a better quantitative understanding of processes in the UTLS. Infrared limb sounding from research aircrafts can provide 2-D cross-sections of multiple trace gas species. In contrast to conventional limb sounders, which are unable to resolve the observed airmass along their line-of-sight, the new GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) instrument enables the 3-D reconstruction of trace gas distributions. This will, among other things, provide highly resolved snapshots of mixing processes than can enhance our quantitative understanding thereof.The proposed work will use GLORIA measurements to reconstruct tracers, which best characterise tropospheric and stratospheric air. First, the best retrievable tracers need to be identified. In a second step the distortion imposed by the retrieval process will be reduced as much a possible. Finally, the derived tracers will be used to analyse the chemical tropopause and horizontal mixing in the vicinity of the sub-tropical jet.