Untersuchung der Auswirkungen von Zirren in hohen Breiten auf die chemische Zusammensetzung der oberen Troposphäre und unteren Stratosphäre
Zusammenfassung der Projektergebnisse
Cirrus clouds and their impact on trace gas budgets in the upper troposphere and lowermost stratosphere (UT/LMS) are important factors modulating climate change. They affect the tropopause region in manifold ways. Accurate simulations of cirrus clouds and trace gas distributions in the UT/LMS pose a challenge for numerical weather prediction (NWP) models and global climate-chemistry models. Significant uncertainties in simulated distributions of clouds and traces gases remain. Among other factors, reasons for these uncertainties are limitations in the microphysical parameterizations for simulating clouds, simulated vertical redistribution of H2O, and modelling of trapping and scavenging of trace gases. The project reported here studied effects by cirrus clouds on the chemical composition of the UT/LMS at high latitudes by using observations by the GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) instrument during the airborne HALO (High Altitude and LOng range research aircraft) mission PGS (POLSTRACC/GW-LCYCLE II/SALSA) in the Arctic winter 2015/16. The GLORIA observations were used to study, how realistic cirrus clouds and trace gas distributions in the UT/LMS are simulated by (i) the new numerical weather prediction (NWP) model ICON (ICOsahedral Nonhydrostatic) with the extension ART (Aerosols and Reactive Trace gases) and (ii) the established climate-chemistry model (CCM) EMAC (ECHAM5/MESSy Atmospheric Chemistry). Furthermore, the potential of a modified cloud filter exploiting the imaging capabilities of GLORIA to enhance the amount of useable GLORIA data in the vicinity of clouds was investigated. Focus of the project was on the HALO research flight on 26 February 2016, which covered deeply subsided air masses of the aged polar vortex, high-latitude LMS air masses, a highly textured troposphere-to-stratosphere exchange region, and high-altitude cirrus clouds. Therefore, this flight constitutes a multifaceted case study allowing for detailed comparisons of GLORIA observations with the model simulations. The presented observations and simulations show that both, the state-of-the-art NWP ICON-ART and the established chemistry-climate model EMAC are capable of simulating UT/LMS cirrus cloud and trace gas distributions in a realistic way. Mesoscale fine structures with a horizontal extent of 50 to 100 km seen in the GLORIA water vapour and ozone data are reproduced well by the highresolution ICON-ART simulation involving a 20 km nest. Surprisingly, faint indications of these features can be identified even in the EMAC simulation, which is characterized by a notably coarser resolution. However, a moist bias in the LMS, which is also known for the ECMWF system, is identified in the simulations by both models. Furthermore, the project reported here contributed to studies validating the quality of ECMWF data. While the established parameterization of ozone loss in EMAC results in good agreement with the GLORIA observations, the applied ozone loss scheme used in the ICON-ART simulations results in an overestimation of ozone loss and may be improved. The EMAC simulations furthermore show that simulation of nitrification of the LMS by sedimentation of particles in polar stratospheric clouds remains challenging. Comparisons of GLORIA methane data with model data could not be addressed, since the GLORIA methane retrieval needs to be further improved. Instead, effects of model resolution on the other trace gases in simulations by EMAC were investigated in an additional sensitivity run and showed systematic changes. Furthermore, since a sensitivity simulation including HNO3 trapping and subsequent effects on ozone was technically not possible, an alternative sensitivity simulation was carried out to investigate the effects of scavenging of trace gases by high clouds. The ICON-ART simulations and comparisons with GLORIA support that cirrus clouds significantly affect UT/LMS water vapour distributions on timescales of hours. Furthermore, scavenging of nitric acid by high clouds is found to noticeably modulate the UT/LMS nitric acid distribution in the EMAC simulation, while scavenging of ozone plays hardly any role here. Further work on chemical impacts of cirrus clouds involving more advanced model parameterisations are encouraged by our study.
Projektbezogene Publikationen (Auswahl)
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GLORIA-Messungen und ECMWF IFS-Vorhersage einer Tropopausenfalte in Interaktion mit einer Schwerewelle,11. Deutsche Klimatagung, 05.–08. März 2018, Frankfurt am Main, DKT-11-30, 201811
Woiwode, W., Dörnbrack, A., Bramberger, M., Höpfner, M., Johansson, S., Oelhaf, H.,Preusse, P., Krisch, I., Ungermann, J., Friedl-Vallon, F., Haenel, F., Heller, R., Hoor P., Krause, J., Kunkel, D., Orphal, J., Sinnhuber, B.-M., and the GLORIA-Team
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Mesoscale fine structure of a tropopause fold over mountains, Atmos. Chem. Phys., 18, 15643-15667
Woiwode, W., Dörnbrack, A., Bramberger, M., Friedl-Vallon, F., Haenel, F., Höpfner, M., Johansson, S., Kretschmer, E., Krisch, I., Latzko, T., Oelhaf, H., Orphal, J., Preusse, P., Sinnhuber, B.-M., and Ungermann, J.
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Possible Feedbacks of Arctic Cirrus Clouds on the Composition of the UTLS, POLAR 2018: Where the Poles come together, SCAR-IASC Open Science Conference, 19-23 June 2018, Davos, Switzerland, A. Schilling Hoyle (editor)
Haenel, F., Woiwode, W., Höpfner, M., Ruhnke, R., Khosrawi, F., Kirner, O., Friedl-Vallon, F., Kleinert, A., and Sinnhuber, B.-M.
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A process study on thinning of Arctic winter cirrus clouds with high-resolution ICON- ART simulations. Journal of Geophysical Research: Atmospheres, 124, 5860– 5888
Gruber, S., Blahak, U., Haenel, F., Kottmeier, C., Leisner, T., Muskatel, H., Storelvmo, T., and Vogel, B.
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IFS Arctic winter/spring 2015/16 LMS moist bias derived from GLORIA observations, ECMWF Workshop: Stratospheric predictability and impact on the troposphere, 18.-21. November 2019 Reading, United Kingdom
Woiwode, W., Dörnbrack, A., Polichtchouk, I. , Johansson, S., Harvey, B. Höpfner, M., Ungermann, J., Friedl-Vallon, F., and GLORIA-Team
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Nitrification of the lowermost stratosphere during the exceptionally cold Arctic winter 2015–2016, Atmos. Chem. Phys., 19, 13681–13699
Braun, M., Grooß, J.-U., Woiwode, W., Johansson, S., Höpfner, M., Friedl-Vallon, F., Oelhaf, H., Preusse, P., Ungermann, J., Sinnhuber, B.-M., Ziereis, H., and Braesicke, P.
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Polstracc: Airborne Experiment for Studying the Polar Stratosphere in a Changing Climate with the High Altitude and Long Range Research Aircraft (HALO). Bull. Amer. Meteor. Soc., 100, 2634–2664
Oelhaf, H., Sinnhuber, B.-M., Woiwode, W., Bönisch, H., Bozem, H., Engel, A., Fix, A., Friedl- Vallon, F., Grooß, J., Hoor, P., Johansson, S., Jurkat-Witschas, T., Kaufmann, S., Krämer, M., Krause, J., Kretschmer, E., Lörks, D., Marsing, A., Orphal, J., Pfeilsticker, K., Pitts, M., Poole, L., Preusse, P., Rapp, M., Riese, M., Rolf, C., Ungermann, J., Voigt, C., Volk, C.M., Wirth, M., Zahn, A., and Ziereis, H.
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Potential Arctic Cirrus Cloud Feedbacks on the Composition of the UTLS, DPG-Frühjahrstagung, 17. - 22. März 2019, München
Haenel, F., Woiwode, W., Höpfner, M., Ruhnke, R., Khosrawi, F., Kirner, O., Friedl-Vallon, F., Johansson, S., Kleinert, A., Schröter, J., and Sinnhuber, B.-M.
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Technical note: Lowermost-stratosphere moist bias in ECMWF IFS model diagnosed from airborne GLORIA observations during winter–spring 2016, Atmos. Chem. Phys., 20, 15379–15387
Woiwode, W., Dörnbrack, A., Polichtchouk, I., Johansson, S., Harvey, B., Höpfner, M., Ungermann, J., and Friedl-Vallon, F.
