Preprints
https://doi.org/10.5194/acp-2021-573
https://doi.org/10.5194/acp-2021-573

  30 Jul 2021

30 Jul 2021

Review status: this preprint is currently under review for the journal ACP.

Positive and negative influences of landfalling typhoons on tropospheric ozone over southern China

Zhixiong Chen1, Jane Liu1,2, Xugeng Cheng1, Mengmiao Yang1, and Hong Wang3 Zhixiong Chen et al.
  • 1Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, School of Geographical Sciences, Fujian Normal University, Fuzhou, China
  • 2Department of Geography and Planning, University of Toronto, Toronto, Ontario, Canada
  • 3Fujian Meteorological Administration, Fuzhou, China

Abstract. In this study, we use an ensemble of 17 landfalling typhoons over 2014–2018 to investigate the positive and negative influences of typhoons on tropospheric ozone over southern China. Referring to the proximity to typhoons and typhoon developmental stages, we found that surface ozone is enhanced when typhoons are 400–1500 km away during the initial stages of typhoons (e.g., from 1 day before and to 1 day after typhoon genesis). The positive ozone anomaly averagely reaches 10–20 ppbv at the daytime and 9 ppbv at nighttime compared with the background ozone level. Particularly, surface ozone at radial distances of 1100–1300 km is most significantly enhanced during these initial stages. As the typhoons approach and land in southern China, the influences of typhoons change from enhancing to reducing ozone. Surface ozone concentrations decrease with a negative ozone anomaly ranging between -12 % ~ -17 % relative to the background ozone level. We explore the physical linkages between typhoons, meteorological conditions and ozone variations. Results show that during typhoon initial stages, the increasing temperature and weak winds in the atmospheric boundary layer (ABL) and dominating downward motions promote ozone production and accumulation over the outskirts of typhoons. While the deteriorating weather accompanied by dropping temperature, wind gales and convective activity reduces the production and accumulation of surface ozone when typhoons are making landfalling.

Variations of tropospheric ozone profiles during the differential developmental stages of landfalling typhoons are further examined to quantify the influences of typhoon-induced stratospheric intrusions on lower troposphere and surface ozone. Using temporally dense ozone vertical observations, we found two regions of high ozone concentrations separately located in the ABL and the middle-to-upper troposphere under the influences of typhoons. Averagely, the ozone enhancement maximizes around 10–12 ppbv at 1–1.5 km altitude at the typhoon initial stages. The ozone enhancement persists over a longer period in the middle-to-upper troposphere with a positive ozone anomaly of 10 ppbv at 7–8 km altitude shortly after typhoon genesis, and 30 ppbv near 12 km altitude when typhoons reach their maximum intensity. When typhoons are landing, a negative ozone anomaly appears and extends upward with a maximum ozone reduction of 14–18 ppbv at 5 km altitude and 20–25 ppbv at 11 km altitude. Though the overall tropospheric ozone is usually reduced during typhoon landfalling, we quantify that five of eight typhoon samples deduce ozone-rich air with the stratospheric origin (80 ppbv) above 4 km altitude, and in 3 typhoon cases the ozone-rich air intrusions (60 ppbv) can sink to the ABL. This suggests that the typhoon-induced stratospheric ozone-rich air intrusions play an important role in surface ozone enhancement.

Zhixiong Chen et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-573', Anonymous Referee #1, 09 Sep 2021
  • RC2: 'Comment on acp-2021-573', Anonymous Referee #2, 10 Sep 2021

Zhixiong Chen et al.

Zhixiong Chen et al.

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Short summary
This study investigates both positive and negative impacts of typhoons on ozone using a large ensemble of typhoons, and addresses the physical linkages between typhoon, meteorological conditions and ozone variations.The influences of typhoon-induced stratospheric intrusions on lower troposphere ozone are also quantified. Thus, the results obtained in this study have important implications on a full understanding of the multifaced roles of typhoons on troposphere and surface ozone.
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