26 Apr 2022
26 Apr 2022
Status: this preprint is currently under review for the journal ACP.

Diagnosing the stratospheric proportion in tropospheric ozone using triple oxygen isotopes as tracers

Hao Xu1, Urumu Tsunogai1, Fumiko Nakagawa1, Keiichi Sato2, and Hiroshi Tanimoto3 Hao Xu et al.
  • 1Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
  • 2Asia Center for Air Pollution Research, 1182 Sowa, Nishi-ku, Niigata-shi, 950-2144, Japan
  • 3National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan

Abstract. Using a multistep nitrite-coated filter-pack system for sampling, we determined the seasonal variations in the triple oxygen isotopic composition (Δ17O) of tropospheric ozone (O3) in the terminal positions (Δ17Oterm(O3)) in the cities Nagoya and Niigata (Japan) in the eastern Asia region to quantify the mixing ratio of stratospheric O3 within the total tropospheric O3 supplied by stratosphere–troposphere transport (STT). In Nagoya, diurnal variations have also been studied. Both the average Δ17Oterm(O3) and their 1σ variation ranges agreed well with previous studies, (37.5 ± 1.4) ‰ in Nagoya and (37.0 ± 1.7) ‰ in Niigata. The average difference in Δ17Oterm(O3) between daytime (higher) and nighttime (lower) was (1.4 ± 0.7) ‰ (1σ) in Nagoya, which was responsible for the formation of a stable boundary layer at night, reducing mixing with high Δ17Oterm(O3) from the free troposphere. We also found a significant correlation between 7Be activity concentrations and the Δ17Oterm(O3), implying that STT was responsible for the elevated Δ17Oterm of O3 in the troposphere. By using the relationship between the reciprocal of concentrations and Δ17Oterm of tropospheric O3, we estimated the Δ17O of stratospheric O3 supplied through the STT (Δ17OSTT), together with that produced through photochemical reactions at surface altitude (Δ17Osur). Moreover, using Δ17OSTT and Δ17Osur, we estimated the mixing ratios of stratospheric O3 (i.e., O3 produced in the stratosphere and supplied to the troposphere through STT) in each tropospheric O3 (fSTT), as well as the absolute concentrations of stratospheric O3 supplied through STT in the troposphere (CSTT(O3)). The CSTT(O3) exhibited minimum values in summer ((5.3 ± 1.0) ppb) and maximum values in late winter to spring ((15.9 ± 2.1) ppb). Although the fSTT values were higher than those estimated using the chemistry climate models from past studies, the trends of the seasonal variations were consistent with them. We concluded that Δ17O successfully provided observational constraints on the STT of O3.

Hao Xu 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-2021-1099', Joel Savarino, 10 Jun 2022
    • AC1: 'Reply on RC1', Hao Xu, 29 Jul 2022
  • RC2: 'Comment on acp-2021-1099', Yunting Fang, 12 Jun 2022
    • AC2: 'Reply on RC2', Hao Xu, 29 Jul 2022

Hao Xu et al.


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Short summary
Using triple oxygen isotopic composition (Δ17O) of ozone as a new tracer, we estimated the absolute concentrations of stratospheric ozone supplied through stratosphere-troposphere transport in the troposphere. We observed the diurnal variations in the Δ17O of ozone, which could have affected studies (field measurements, atmospheric modeling) using Δ17O to constrain atmospheric chemical paths. Our study provides an important basis for a better understanding of ozone behavior in the troposphere.