A140-02
Convective genesis of cirrus clouds above the Asian monsoon tropopause from StratoClim airborne measurements, satellite observations and meteorological analysis
Monday, 14 December 2020: 04:04
Virtual
Sergey Khaykin1, Martina Krämer2, Elisabeth J Moyer3, Alexey Lykov4, Silvia Bucci5, Andreas Dörnbrack6, Armin Afchine2, Stephan Borrmann7, Francesco Cairo8, Benjamin Clouser9, Francesco D’Amato10, Bernard Legras11, Velentin Mitev12, Renaud Matthey13, Fabrizio Ravegnani8, Christian Rolf14, Alexey Ulanovsky15, Silvia Viciani10, C Michael Volk16, Vladimir A Yushkov15 and Fred Stroh17, (1)LATMOS/IPSL, UVSQ, Sorbonne Université, CNRS, Paris Cedex 05, France, (2)Forschungszentrum Juelich, Juelich, Germany, (3)University of Chicago, Department of the Geophysical Sciences, Center for Robust Decision-making on Climate and Energy Policy (RDCEP), Chicago, IL, United States, (4)Central Aerological Observatory of RosHydroMet, Dolgoprudny, Russia, (5)National Research Council (CNR), Institute of Atmospheric Sciences and Climate (ISAC), Rome, Italy, (6)German Aerospace Center (DLR), Institute of Atmospheric Physics, Oberpfaffenhofen, Germany, (7)Johannes Gutenberg University, Max Planck Institute for Chemistry, Particle Chemistry, Mainz, Germany, (8)Institute of Atmospheric Science and Climate, ISAC-CNR, Rome, Italy, (9)University of Chicago, Geophysical Sciences, Chicago, IL, United States, (10)CNR-INO National Institute of Optics, Florence, Italy, (11)Laboratoire de Météorologie Dynamique ENS, Paris, France, (12)Centre Suisse d’Electronique et de Microtechnique Neuchatel, Neuchatel, Switzerland, (13)LTF-University of Neuchatel, Neuchatel, Switzerland, (14)Forschungszentrum Juelich, IEK-7, Juelich, Germany, (15)Central Aerological Observatory of RosHydroMet, Moscow, Russia, (16)Bergische Univ. Wuppertal, Wuppertal, Germany, (17)Forschungszentrum Juelich, Jülich, Germany
Abstract:
Deployment of the high-altitude M55-Geophysica aircraft in Kathmandu within the StratoClim campaign in Summer 2017 has yielded a wealth of unique high-resolution measurements in the lower stratosphere above the Asian Monsoon Anticyclone (AMA). We combine the airborne measurements of clouds, water vapour and other convective tracers with satellite observations of cloud tops and high-resolution meteorological analysis by ECMWF Integrated Forecasting System to explore the convective influence on the formation and physical properties of the clouds above the AMA tropopause.
We provide evidence for the stratospheric clouds of different genesis: convectively-injected clouds, secondary clouds condensing from a convectively-moistened patch of air, and in situ clouds forming at background levels of water vapour and modulated by orographic and/or convective gravity waves. Special attention is given to a particular flight, in which the aircraft flew through active stratospheric overshoots and sampled convective outflows above the tropopause minutes to hours old. The measurements reveal up to 2500 ppmv of ice water above 17 km in large aggregates measuring up to 750 µm in diameter. The tracer measurements show striking perturbations reflecting vigorous vertical motions and provide evidence for rapid mixing of tropospheric and stratospheric air around the tropopause.
Our analysis suggests that the climatological maximum of stratospheric cirrus above AMA during August is a result of two concurrent processes: i) hydration by overshooting convection in the subtropical parts of AMA and ii) tropopause cooling induced by large-scale organized convective systems above Southern Asia. We discuss the dehydration potential of different types of clouds as well as the role of gravity waves in modulation of the three-dimensional cloud structure.
