The TWIN - Hemera stratospheric balloon flight: sulfur, halogens and tracers in the stratosphere

<p>The TWIN - Hemera stratospheric balloon flight took place on 12 - 13-Aug-2021 from the Esrange Space Center near Kiruna, Sweden (67&#176;N).The project was supported by Hemera (www.hemera-h2020.eu) via the first call of proposals, and the flight was managed by the CNES (Centre national d'Etudes Spatiales) and SSC (Swedish Space Corporation). The scientific payload was developed in collaboration by several institutions from the Netherlands, Germany and France.</p><p>The main objectives were: (1) to characterize the vertical structure of COS mole fraction and isotopic composition; (2) to characterize the CFCs, other ozone depleting substances and climate relevant trace gases in the present atmosphere, linked to their change over the past decade; and (3) to compare and evaluate several instruments and sampling techniques.</p><p>The payload included several AirCores (U. Frankfurt, CIO and FZJ), two Pico-SDLA mid-infrared in-situ diode laser spectrometers (GSMA/DT-INSU), and devices for taking large whole air samples of stratospheric air for subsequent laboratory measurements: the BONBON whole-air cryosampler (U. Frankfurt) and LISA (CIO). IMAU is involved for the analysis of isotopic composition and mole fractions of samplers from the cryo-sampler. This approach allows obtaining a comprehensive dataset covering a range of spatial resolutions: from the multitude of gas species to be measured in the high-volume samples, to the subset of gases at higher vertical resolution from AirCores, and finally to the continuous in-situ CO₂ and CH₄ data from tunable diode laser spectroscopy. We expect this dataset to lead to novel and important knowledge on the trace gases in the stratosphere.</p><p>In this presentation we will describe the overall setup of the scientific payload, the flight characteristics, and we will give an overview of the already performed and planned measurements.</p>