In situ tracer measurements with HAGAR-V during the HALO mission WISE and UTLS transport analysis based on POLSTRACC/GW-LCYCLE/SALSA and WISE tracer data

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In the frame of this project we propose i) in situ measurements of a suite of tracers with the new HAGAR-V instrument during the HALO WISE mission in summer 2017, and ii) scientific analysis of HAGAR-V tracer data obtained during WISE and during the POLSTRACC/GW-LCYCLE/SALSA mission in winter 2015/16. HAGAR-V combines a fast CO2 measurement by NDIR analyzer, a 2-channel GC/ECD-system measuring long-lived tracers (N2O, CH4, F12, F11, H1211, SF6, H2 every 90 s) and a 2-channel GC/MS system targeting short-lived tracers (NMHCs and chlorinated hydrocarbons every 90 s) with local lifetimes at the midlatitude tropopause ranging from several days to just under a year. Owing to their different chemical time scales, the distributions of these tracers provide complementary information on time scales of transport and mixing; it is even possible to empirically derive the spectrum of stratospheric transport times ("age spectrum") from such observations. The analysis of the HAGAR-V tracer data will contribute to the scientific topics of POLSTRACC, SALSA and WISE by addressing a number of these missions' objectives relating to UTLS transport. In particular, fractions of air from different regions of origin (polar vortex, mid-latitude stratosphere, tropical transition layer, Asian monsoon region) will be determined. Of central importance is the calculation of the mean age of air from SF6 and (in the upper LMS) from CO2. In addition, empirical age spectra will be derived using information from the CO2 seasonal variation and, more importantly, from the short-lived HAGAR-V tracers. The variety of tracers of different lifetimes also allows for a detailed process characterization of horizontal transport and mixing in the UTLS. This involves investigation of Rossby wave transport by identifying filaments entrained from different regions and assessing their transport time. The evolution and irreversible mixing of such filaments with the surrounding stratosphere will be investigated by so-called mixing lines in (non-linear) tracer-tracer curves. Additional goals include the validation of the GLORIA IR-imager, which observes many of the HAGAR-V species, and the validation of chemistry transport models, in particular the Lagrangian CLaMS model.