Tracer measurements with HAGAR-V during PHILEAS to investigate the impact of the Asian monsoon on the extratropical UTLS

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In the frame of this project we propose i) in situ measurements of a suite of tracers with the novel HAGAR-V instrument during the HALO PHILEAS mission in the summer of 2023 and ii) analysis of the obtained HAGAR-V tracer data toward the scientific goals of that mission. HAGAR-V combines a fast CO2 measurement by NDIR analyzer, a 2-channel GC/ECD-system measuring long-lived tracers (SF6 and F12 every 45 s; Halon-1211, F11 and F113 every 90 s) and a 2-channel GC/MS system targeting a suite of further tracer species every 90 s, including NMHC (C2H2, iso-&n-C5H12), short-lived chlorocarbons (CH2Cl2, CHCl3, C2Cl4), and further long-lived halocarbons (CCl4, CHCl3, HFC-125, HFC-134a, HFC-32). HAGAR-V thus covers most major chlorine source gases as well as the most important chlorinated VSLS. Local lifetimes of these species at the midlatitude tropopause range from several days to many years, which will be used along with the seasonal variation of CO2 in combination with meteorological data and CLaMS simulations to constrain transport time scales and dominant transport paths from the Asian Monsoon anticyclone (AMA) into the extratropical UTLS. The species CH2Cl2 and CHCl3 are strongly enhanced inside the AMA and will be used together with long-lived tracers to study the structure and mixing of eddies shed from the AMA, to derive fractions of air origin from the AMA and other regions, and to assess the impact of air export from the AMA on the composition of the northern lowermost stratosphere. Further, the measurements of NMHC will allow to detect influence of fresh pollution and biomass burning and thus contribute to the investigation of aerosol precursors.