Influences of oceanic ozone deposition on tropospheric photochemistry

Pound, Ryan; Sherwen, Tomás; Helmig, Detlev; Carpenter, Lucy J.; Evans, M. J.

doi:10.5194/acp-20-4227-2020

Cited by 42 publications

(40 citation statements)

References 35 publications

(65 reference statements)

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“…Incorporating such a deposition scheme into the UK Chemistry and Aerosol CCM (UKCA; Luhar et al, 2018) decreases ozone deposition over the ocean by almost half, which corresponds to a 10 % decrease in the model calculated total global ozone deposition. Similar results are obtained in a study with an updated surface ocean iodide distribution and the Luhar et al (2018) scheme with the GEOS-Chem chemical transport model (CTM;Pound et al, 2020). An overall downward revision of global ozone deposition rates can be expected as these rates are more widely adopted.…”

Section: Development Of Emissions Inventoriessupporting

confidence: 83%

Tropospheric Ozone Assessment Report

Archibald

Neu

Elshorbany

et al. 2020

Elementa: Science of the Anthropocene

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Our understanding of the processes that control the burden and budget of tropospheric ozone has changed dramatically over the last 60 years. Models are the key tools used to understand these changes, and these underscore that there are many processes important in controlling the tropospheric ozone budget. In this critical review, we assess our evolving understanding of these processes, both physical and chemical. We review model simulations from the International Global Atmospheric Chemistry Atmospheric Chemistry and Climate Model Intercomparison Project and Chemistry Climate Modelling Initiative to assess the changes in the tropospheric ozone burden and its budget from 1850 to 2010. Analysis of these data indicates that there has been significant growth in the ozone burden from 1850 to 2000 (approximately 43 ± 9%) but smaller growth between 1960 and 2000 (approximately 16 ± 10%) and that the models simulate burdens of ozone well within recent satellite estimates. The Chemistry Climate Modelling Initiative model ozone budgets indicate that the net chemical production of ozone in the troposphere plateaued in the 1990s and has not changed since then inspite of increases in the burden. There has been a shift in net ozone production in the troposphere being greatest in the northern mid and high latitudes to the northern tropics, driven by the regional evolution of precursor emissions. An analysis of the evolution of tropospheric ozone through the 21st century, as simulated by Climate Model Intercomparison Project Phase 5 models, reveals a large source of uncertainty associated with models themselves (i.e., in the way that they simulate the chemical and physical processes that control tropospheric ozone). This structural uncertainty is greatest in the near term (two to three decades), but emissions scenarios dominate uncertainty in the longer term (2050–2100) evolution of tropospheric ozone. This intrinsic model uncertainty prevents robust predictions of near-term changes in the tropospheric ozone burden, and we review how progress can be made to reduce this limitation.

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Section: Development Of Emissions Inventoriessupporting

confidence: 83%

Tropospheric Ozone Assessment Report

Archibald

Neu

Elshorbany

et al. 2020

Elementa: Science of the Anthropocene

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“…Tropospheric ozone is important due to its considerable effects on human health (Medina-Ramón et al, 2006), agricultural yields (Heck et al, 1982), and global warming (Stevenson et al, 2013). Dry deposition is a major sink of tropospheric ozone, comprising as much as 25 % of total loss from the troposphere (Ganzeveld et al, 2009;Lelieveld and Dentener, 2000;Pound et al, 2020). Deposition to the sea surface is the greatest source of uncertainty in global estimates Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

“…When a variable reaction-diffusion sublayer depth was considered as being proportional to the reactiondiffusion length scale (l m = √ D/a), Luhar et al (2018) found it necessary to multiply l m by a factor of 0.7 to obtain a δ m value that fitted reasonably with observations. Pound et al (2020) were however able to obtain a good fit to observational data without this factor by using the oceanic iodide parameterisation of Sherwen et al (2019) in place of that of Macdonald et al (2014). Pound et al (2020) define the reaction-diffusion layer depth according to Eq.…”

Section: Introductionmentioning

confidence: 99%

“…Pound et al (2020) were however able to obtain a good fit to observational data without this factor by using the oceanic iodide parameterisation of Sherwen et al (2019) in place of that of Macdonald et al (2014). Pound et al (2020) define the reaction-diffusion layer depth according to Eq. (11).…”

Section: Introductionmentioning

confidence: 99%

“…The two-layer model of Luhar et al (2018) predicts almost no influence of friction velocity on deposition velocity, except at very low (< 2 m s −1 ) wind speeds. Better characterisation of the effects of wind speed and the chemical composition of the surface water on ozone deposition velocity to the sea surface would significantly improve our understanding of the global tropospheric O 3 budget (Ganzeveld et al, 2009;Pound et al, 2020). Here we present coastal ozone flux measurements made at Penlee Point Atmospheric Observatory (PPAO; https:// www.westernchannelobservatory.org.uk/penlee/, last access: 10 December 2020) on the south-west coast of the UK using a fast-response gas-phase chemiluminescence detector (CLD).…”

Section: Introductionmentioning

confidence: 99%

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Ozone deposition to a coastal sea: comparison of eddy covariance observations with reactive air–sea exchange models

et al. 2020

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Abstract. A fast-response (10 Hz) chemiluminescence detector for ozone (O3) was used to determine O3 fluxes using the eddy covariance technique at the Penlee Point Atmospheric Observatory (PPAO) on the south coast of the UK during April and May 2018. The median O3 flux was −0.132 mg m−2 h−1 (0.018 ppbv m s−1), corresponding to a deposition velocity of 0.037 cm s−1 (interquartile range 0.017–0.065 cm s−1) – similar to the higher values previously reported for open-ocean flux measurements but not as high as some other coastal results. We demonstrate that a typical single flux observation was above the 2σ limit of detection but had considerable uncertainty. The median 2σ uncertainty of deposition velocity was 0.031 cm s−1 for each 20 min period, which reduces with the square root of the sample size. Eddy covariance footprint analysis of the site indicates that the flux footprint was predominantly over water (> 96 %), varying with atmospheric stability and, to a lesser extent, with the tide. At very low wind speeds when the atmosphere was typically unstable, the observed ozone deposition velocity was elevated, most likely because the footprint contracted to include a greater land contribution in these conditions. At moderate to high wind speeds when atmospheric stability was near-neutral, the ozone deposition velocity increased with wind speed and showed a linear dependence with friction velocity. This observed dependence on friction velocity (and therefore also wind speed) is consistent with the predictions from the one-layer model of Fairall et al. (2007), which parameterises the oceanic deposition of ozone from the fundamental conservation equation, accounting for both ocean turbulence and near-surface chemical destruction, while assuming that chemical O3 destruction by iodide is distributed over depth. In contrast to our observations, the deposition velocity predicted by the recently developed two-layer model of Luhar et al. (2018) (which considers iodide reactivity in both layers but with molecular diffusivity dominating over turbulent diffusivity in the first layer) shows no major dependence of deposition velocity on wind speed and underestimates the measured deposition velocities. These results call for further investigation into the mechanisms and control of oceanic O3 deposition.

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