AREA MAP - etb Homes · 9/19/2019 · sandra.brodnaxevrealestate.com Information is believed accurate, but not warranted. Locations are approximate. 09-04-19 EMEM AREA MAP. Red Top

Understanding cryogenic frost point hygrometer measurements after contamination by mixed-phase clouds Teresa Jorge 1 , Simone Brunamonti 1 , Yann Poltera 1 , Frank G. Wienhold 1 , Bei P. Luo 1 , Peter Oelsner 2 , Sreeharsha Hanumanthu 3 , Bhupendra B. Singh 4,5 , Susanne Körner 2 , Ruud Dirksen 2 , Manish Naja 6 , Suvarna Fadnavis 4 , and Thomas Peter 1 1 Institute of Atmospheric and Climate Science, ETH Zürich 2 Deutscher Wetterdienst (DWD)/ GCOS Reference Upper Air Network (GRUAN) Lead Center, Lindenberg, Germany 3 Forschungzentrum Jülich (FZJ), Institute of Energy and Climate Research, Stratosphere (IEK-7), Jülich, Germany 4 Indian Institute of Tropical Meteorology (IITM), Pune, India 5 Department of Geophysics, Banaras Hindu University, Varanasi, India 6 Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, India Correspondence: Teresa Jorge ([email protected]) Abstract. Balloon-borne water vapour measurements in the (sub)tropical upper troposphere and lower stratosphere (UTLS) by means of frost point hygrometers provide important information on air chemistry and climate. However, the risk of contamination from sublimating hydrometeors collected by the intake tube may render these measurements difficult, particularly after crossing low clouds containing supercooled droplets. A large set of measurements during the 2016-2017 StratoClim balloon campaigns at the southern slopes of the Himalayas allows us to perform an in-depth analysis of this type of contamination. We 5 investigate the efficiency of wall-contact and freezing of supercooled droplets in the intake tube and the subsequent sublimation in the UTLS using Computational Fluid Dynamics (CFD). We find that the airflow can enter the intake tube with impingement angles up to 60 ◦ , owing to the pendulum motion of the payload. Supercooled droplets with radii > 70 μm, as they frequently occur in mid-tropospheric clouds, typically undergo contact freezing when entering the intake tube, whereas only about 50% of droplets with 10 μm radius freeze, and droplets < 5 μm radius mostly avoid contact. According to CFD, sublimation of 10 water from an icy intake can account for the occasionally observed high water vapour mixing ratios (χ H2O > 100 ppmv) in the stratosphere. Furthermore, we use CFD to differentiate between stratospheric water vapour contamination by an icy intake tube and contamination caused by outgassing from the balloon and payload, revealing that the latter starts playing a role only at high altitudes (p < 20 hPa). Copyright statement. The authors declare this is an original work 15 1 https://doi.org/10.5194/amt-2020-176 Preprint. Discussion started: 29 May 2020 c Author(s) 2020. CC BY 4.0 License.

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AREA MAP - etb Homes · 9/19/2019 · sandra.brodnaxevrealestate.com Information is believed accurate, but not warranted. Locations are approximate. 09-04-19 EMEM AREA MAP. Red Top