Impact of typhoons on the composition of the upper troposphere within the Asian summer monsoon anticyclone: the SWOP campaign in Lhasa 2013
Dan Li1,2, Bärbel Vogel2, Jianchun Bian1,3, Rolf Müller2, Laura L. Pan4, Gebhard Günther2, Zhixuan Bai1,3, Qian Li1, Jinqiang Zhang1, Qiujun Fan1,3, and Holger Vömel51Key Laboratory of Middle Atmosphere and Global Environment Observation (LAGEO), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China 2Institute of Energy and Climate Research: Stratosphere (IEK-7), Forschungszentrum Jülich, Jülich, Germany 3College of Earth Science, University of Chinese Academy of Sciences, Beijing, China 4Atmospheric Chemistry Observations & Modeling, National Center for Atmospheric Research, Boulder, CO, USA 5Earth Observing Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
Received: 30 Sep 2016 – Accepted for review: 22 Oct 2016 – Discussion started: 25 Oct 2016
Abstract. In the frame of the SWOP (sounding water vapour, ozone, and particle) campaign during the Asian summer monsoon (ASM), ozone and water vapour profiles were measured by balloon-borne sensors launched from Lhasa (29.66° N, 91.14° E, elevation 3650 m), China, in August 2013. In total, 24 soundings were launched, nearly half of which show some strong variations in the relationship between ozone and water vapour in the tracer-tracer correlation in the upper troposphere and lower stratosphere (UTLS). 20-day backward trajectories of each sounding were calculated using the trajectory module of the Chemical Lagrangian Model of the Stratosphere (CLaMS) to analyse these variations. The trajectory calculations demonstrate that three tropical cyclones (tropical storm Jebi, typhoons Utor and Trami), which occurred over the Western Pacific Ocean during August 2013, had a considerable impact on the vertical distribution of ozone and water vapour by uplifting marine air masses to altitudes of the ASM anticyclone. Air parcels subsequently arrived at the observation site via two primary pathways: firstly via direct horizontal transport from the location of the typhoon to the station within approximately three days, and secondly via rotational subsidence, during which air parcels descend slowly along a circle following the anticyclone flow within a timescale of one week. Furthermore, the interplay between the spatial position of the ASM anticyclone and tropical cyclones plays a key role in controlling the transport pathways of air parcels from the boundary layer of the Western Pacific to Lhasa in horizontal as well as vertical transport. Moreover, the statistical analysis shows that the strongest impact by typhoons is found at altitudes between 14.5 km and 17 km (365–375 K). Low ozone values (50–80 ppbv) were observed between 370 K and 380 K due to the strong vertical transport within tropical cyclones.
Li, D., Vogel, B., Bian, J., Müller, R., Pan, L. L., Günther, G., Bai, Z., Li, Q., Zhang, J., Fan, Q., and Vömel, H.: Impact of typhoons on the composition of the upper troposphere within the Asian summer monsoon anticyclone: the SWOP campaign in Lhasa 2013, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-875, in review, 2016.