Status: this preprint is currently under review for the journal ACP.
Arctic tropospheric ozone: assessment of current knowledge and model performance
Cynthia H. Whaley1,Kathy S. Law2,Jens Liengaard Hjorth3,Henrik Skov3,Stephen R. Arnold4,Joakim Langner5,Jakob Boyd Pernov3,a,Rong-You Chien6,Jesper H. Christensen3,Makoto Deushi11,Xinyi Dong6,Gregory Faluvegi7,8,Mark Flanner9,Joshua S. Fu6,Michael Gauss10,Ulas Im3,Louis Marelle2,Tatsuo Onishi2,Naga Oshima11,David A. Plummer1,Luca Pozzoli12,b,Jean-Christophe Raut2,Ragnhild Skeie13,Manu A. Thomas5,Kostas Tsigaridis8,Svetlana Tsyro10,Steven T. Turnock14,4,Knut von Salzen1,and David W. Tarasick15Cynthia H. Whaley et al.Cynthia H. Whaley1,Kathy S. Law2,Jens Liengaard Hjorth3,Henrik Skov3,Stephen R. Arnold4,Joakim Langner5,Jakob Boyd Pernov3,a,Rong-You Chien6,Jesper H. Christensen3,Makoto Deushi11,Xinyi Dong6,Gregory Faluvegi7,8,Mark Flanner9,Joshua S. Fu6,Michael Gauss10,Ulas Im3,Louis Marelle2,Tatsuo Onishi2,Naga Oshima11,David A. Plummer1,Luca Pozzoli12,b,Jean-Christophe Raut2,Ragnhild Skeie13,Manu A. Thomas5,Kostas Tsigaridis8,Svetlana Tsyro10,Steven T. Turnock14,4,Knut von Salzen1,and David W. Tarasick15
Received: 30 Apr 2022 – Discussion started: 17 May 2022
Abstract. As the third most important greenhouse gas (GHG) after CO2 and methane, tropospheric ozone (O3) is also an air pollutant causing damage to human health and ecosystems. This study brings together recent research on observations and modeling of tropospheric O3 in the Arctic, a rapidly warming and sensitive environment. At different locations in the Arctic, the observed surface O3 seasonal cycles are quite different. Coastal Arctic locations, for example, have a minimum in the springtime due to O3 depletion events resulting from surface bromine chemistry. In contrast, other Arctic locations have a maximum in the spring. The 12 state-of-the-art models used in this study lack the surface halogen chemistry needed to simulate coastal Arctic surface O3 depletion in the springtime, however, the multi-model median (MMM) has accurate seasonal cycles at non-coastal Arctic locations. There is a large amount of variability among models, which has been reported previously, and we show that there continues to be no convergence among models, nor improved accuracy in simulating tropospheric O3 and its precursor species. The MMM underestimates Arctic surface O3 by 5 % to 15 % depending on the location. The vertical distribution of tropospheric O3 is studied from recent ozonesonde measurements and the models. The models are highly variable, simulating free-tropospheric O3 within a range of +/- 50 % depending on the model and the altitude. The MMM performs best, within +/- 8 % at most locations and seasons. However, nearly all models overestimate O3 near the tropopause (~300 hPa or ~8 km), likely due to ongoing issues with underestimating the altitude of the tropopause and excessive downward transport of stratospheric O3 at high latitudes. For example, the MMM is biased high by about 20 % at Eureka. Observed and simulated O3 precursors (CO, NOx and reservoir PAN) are evaluated throughout the troposphere. Models underestimate wintertime CO everywhere, likely due to a combination of underestimating CO emissions and possibly overestimating OH. Throughout the vertical profile (compared to aircraft measurements), the MMM underestimates both CO and NOx but overestimates PAN. Perhaps as a result of competing deficiencies, the MMM O3 matches the observed O3 reasonably well. Our findings suggest that despite model updates over the last decade , model results are as highly variable as ever, and have not increased in accuracy for representing Arctic tropospheric.
This study summarizes recent research on ozone in the Arctic, a sensitive and rapidly warming region. We find that the seasonal cycles of near-surface atmospheric ozone is variable depending on whether near the coast or in-land. Several global model simulations were evaluated and we found that because models lack some of the ozone chemistry that is important for the coastal Arctic locations, they do not accurate simulate ozone there.
This study summarizes recent research on ozone in the Arctic, a sensitive and rapidly warming...