DECOR: Dynamical Effects on Composition and transport Of climate Relevant species, in the extratropical upper troposphere lower and stratosphere region

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Quantifying the roles of transport, mixing and chemical processing of climate relevant traces species in the upper troposphere lower stratosphere region is of major importance for understanding its radiation budget. Regional to large scale dynamical regimes such as jet streams, the monsoon outflow, gravity waves or Rossby wave breaking modify the distribution of trace species in the UTLS and thereby have an impact on UTLS stability, irreversible transport and climate. It is the scope of this project to investigate and quantify changes in the composition and transport in the UTLS region induced by selected dynamical processes with a special focus on the trace gases water vapour, ozone, nitrogen oxide and halogen species as well as cirrus clouds. To this end, we have developed the Airborne Mass Spectrometer AIMS and the tunable diode laser hygrometer WARAN and we will integrate them on HALO for the WISE mission. Previously, unique measurements on HALO have been performed with this instrumentation during TACTS/ESMVal, ML-CIRRUS and POLSTRACC/GW-Cycle/SALSA. Thereby AIMS uses the chemical ionization with SF5- ions to detect HCl, HNO3, SO2 and HONO in the UTLS region. Here we propose two calibration methods to quantitatively detect ClONO2 and HBr in future HALO experiments. During WISE, we will investigate the contributions of stratospheric tracers such as HCl, HNO3, O3 and the tropospheric tracer SO2 in the extratropical UTLS and near the tropopause inversion layer (TIL). Depending on latitude and season we will focus on transport processes that modify the TIL. We will measure the effects of irreversible mixing in the ExUTLS and above using tracer-tracer correlations. We will investigate stratospheric tracer-tracer correlations in the region above the ExTL and compare them to mixed layers below. Selected dynamical regimes like the Asian Summer Monsoon as well as Rossby wave breaking near the subtropical jet in summer results in dilution or flushing of the lower stratosphere. Further we will compare our in-situ measurements to remote sensing data from GLORIA (HNO3, ClONO2, H2O and SO2), DOAS (HONO, Bry) and WALES (H2O). A second focus is the data evaluation from the POLSTRACC/GW-Cycle/SALSA mission. Here, we will investigate the halogen processing on cold stratospheric aerosol using Lagrangian flights. Further we will concentrate on the nitric acid uptake in cold cirrus ice crystals. Dedicated uncertainties remain in understanding uptake of HNO3 and effects of nitric acid trihydrate (NAT) or other condensed water / nitric acid phases on UTLS composition and climate at low temperatures. These questions will be analyzed using the ice water content from the WARAN hygrometer and AIMS HNO3 data in concert with total reactive nitrogen detected with AENEAS on HALO. Summarized our measurements will help to better understand and quantify the effects of dynamics and clouds on the distribution of climate relevant species in the ExUTLS region.