Print Email Facebook Twitter Dynamics and composition of the Asian summer monsoon anticyclone Title Dynamics and composition of the Asian summer monsoon anticyclone Author Gottschaldt, Klaus Dirk (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Schlager, Hans (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Baumann, Robert (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Sinh Cai, Duy (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Eyring, Veronika (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Graf, Phoebe (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Grewe, V. (TU Delft Aircraft Noise and Climate Effects; Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Jöckel, Patrick (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Jurkat-Witschas, Tina (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Voigt, Christiane (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR); University of Mainz) Zahn, Andreas (Karlsruhe Institut für Technologie) Ziereis, Helmut (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Date 2018-04-24 Abstract This study places HALO research aircraft observations in the upper-tropospheric Asian summer monsoon anticyclone (ASMA) into the context of regional, intra-annual variability by hindcasts with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model. The observations were obtained during the Earth System Model Validation (ESMVal) campaign in September 2012. Observed and simulated tracer-tracer relations reflect photochemical O3 production as well as in-mixing from the lower troposphere and the tropopause layer. The simulations demonstrate that tropospheric trace gas profiles in the monsoon season are distinct from those in the rest of the year, and the measurements reflect the main processes acting throughout the monsoon season. Net photochemical O3 production is significantly enhanced in the ASMA, where uplifted precursors meet increased NO, mainly produced by lightning. An analysis of multiple monsoon seasons in the simulation shows that stratospherically influenced tropopause layer air is regularly entrained at the eastern ASMA flank and then transported in the southern fringe around the interior region. Radial transport barriers of the circulation are effectively overcome by subseasonal dynamical instabilities of the anticyclone, which occur quite frequently and are of paramount importance for the trace gas composition of the ASMA. Both the isentropic entrainment of O3-rich air and the photochemical conversion of uplifted O3-poor air tend to increase O3 in the ASMA outflow. To reference this document use: http://resolver.tudelft.nl/uuid:e67a9a51-b243-4633-ac32-8e93fb67dec7 DOI https://doi.org/10.5194/acp-18-5655-2018 ISSN 1680-7316 Source Atmospheric Chemistry and Physics (online), 18 (8), 5655-5675 Part of collection Institutional Repository Document type journal article Rights © 2018 Klaus Dirk Gottschaldt, Hans Schlager, Robert Baumann, Duy Sinh Cai, Veronika Eyring, Phoebe Graf, V. Grewe, Patrick Jöckel, Tina Jurkat-Witschas, Christiane Voigt, Andreas Zahn, Helmut Ziereis Files PDF acp_18_5655_2018.pdf 23.73 MB Close viewer /islandora/object/uuid:e67a9a51-b243-4633-ac32-8e93fb67dec7/datastream/OBJ/view