Temporal and spatial characteristics of ozone depletion events from measurements in the Arctic

Halfacre, J. W.; Knepp, T. N.; Shepson, P. B.; Thompson, C. R.; Pratt, Kerri A.; Li, B.; Peterson, Peter K.; Walsh, Stephen J.; Simpson, W. R.; Matrai, Patricia A.; Bottenheim, J. W.; Netcheva, S.; Perovich, Donald K.; Richter, Andreas

doi:10.5194/acp-14-4875-2014

Cited by 49 publications

(74 citation statements)

References 93 publications

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“…Based on these results, it can be concluded that iodine has the potential to have a much greater impact on ozone depletion than chlorine. The combination of Br, Cl and low iodine, resulting in an 8.5 h depletion timescale, is consistent with the fast-end timescales observed over the Beaufort Sea by Halfacre et al (2014).…”

Section: Atmossupporting

confidence: 69%

“…Backtrajectories for periods of very high [Cl 2 ] during OASIS indicate air mass transport over the surface of the Arctic Ocean . Ozone instruments onboard the OBuoy network of sea ice-tethered buoys (Knepp et al, 2010) in the Arctic Ocean have also indicated very fast ozone depletions, with a median timescale of 10.4 h and numerous individual events much faster than that (Halfacre et al, 2014). Unfortunately, we are limited by a lack of Cl 2 measurements from across the frozen Arctic Ocean, and, thus, it is not possible to speculate how widespread this elevated Cl 2 may be.…”

Section: Atmosmentioning

confidence: 96%

“…For comparison, the Base Model with low iodine as shown in Table 8 has an ozone depletion timescale of 8.47 h, whereas the Base Model with High Iodine has a depletion timescale of 4.94 h. Thus, the presence of only 0.025 pptv of I 2 has a greater effect on the ozone depletion rate than does 100 pptv of Cl 2 , and sustained levels of Cl 2 greater than 400 pptv would be required to have a comparable impact on ozone depletion, as does 0.5 pptv I 2 . Although the depletion timescales reported here, both for Base Model conditions and for elevated [Cl 2 ], represent relatively fast ozone depletion and, as stated, represent an upper limit assuming a constant ozone depletion rate, total ozone depletions are often observed to occur on timescales of a day or less (Tang and McConnell, 1996;Simpson et al, 2007;Halfacre et al, 2014), and a fast ozone depletion of ∼ 7 h attributed to local chemistry was reported over the Arctic Ocean by Jacobi et al (2006). Thus, the ozone depletion rates calculated here (including for elevated [Cl 2 ]) show that rapid photochemical ozone depletion events are possible, and thus one should not assume that all fast ODEs represent transport, without appropriate supporting information.…”

Section: Atmosmentioning

confidence: 99%

“…Often, fast apparent ozone depletions, in which O 3 is observed to decrease over timescales of hours, have been attributed to air mass transport of ozone-depleted air, whereas local chemistry is believed to result in a more gradual depletion (Bottenheim and Chan, 2006;Simpson et al, 2007;Halfacre et al, 2014). The ozone depletion rate and the resulting timescale for depletion induced by Br, Cl, and I, both in isolation (for Br and I) and when allowed to interact, were investigated with model runs conducted for "Br Only" and "I Only", as well as with different combinations of the above, including both Low Iodine and High Iodine conditions.…”

Section: Atmosmentioning

confidence: 99%

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Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska

et al. 2015

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Abstract. The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs) has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there have been indications of active iodine chemistry through observed enhancements in filterable iodide, probable detection of tropospheric IO, and recently, observation of snowpack photochemical production of I 2 . Despite decades of research, significant uncertainty remains regarding the chemical mechanisms associated with the bromine-catalyzed depletion of ozone, as well as the complex interactions that occur in the polar boundary layer due to halogen chemistry. To investigate this, we developed a zero-dimensional photochemical model, constrained with measurements from the 2009 OA-SIS field campaign in Barrow, Alaska. We simulated a 7-day period during late March that included a full ozone depletion event lasting 3 days and subsequent ozone recovery to study the interactions of halogen radicals under these different conditions. In addition, the effects of iodine added to our Base Model were investigated. While bromine atoms were primarily responsible for ODEs, chlorine and iodine were found to enhance the depletion rates and iodine was found to be more efficient per atom at depleting ozone than Br. The interaction between chlorine and bromine is complex, as the presence of chlorine can increase the recycling and production of Br atoms, while also increasing reactive bromine sinks under certain conditions. Chlorine chemistry was also found to have significant impacts on both HO 2 and RO 2 , with organic compounds serving as the primary reaction partner for Cl atoms. The results of this work highlight the need for future studies on the production mechanisms of Br 2 and Cl 2 , as well as on the potential impact of iodine in the High Arctic.

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Section: Atmossupporting

confidence: 69%

Section: Atmosmentioning

confidence: 96%

Section: Atmosmentioning

confidence: 99%

Section: Atmosmentioning

confidence: 99%

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Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska

et al. 2015

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“…In order to investigate the hinted heterogeneity of the Antarctic lower troposphere regarding reactive bromine (BrOx = Br + BrO), in this section the budget of bromine [Br] is estimated considering steady state of BrO in a pristine atmosphere with virtually no NO (e.g., Zeng at al., 2006) and a concentration of ClO, HO2 and OH of 1.7·10 8 molec cm -3 , 2.2·10 7 molec cm -3 20 and 3.9·10 5 molec cm -3 , respectively (e.g., Halfacre et al, 2014;Bloss et al, 2007). Hence, [Br] can be estimated from the observed BrO and O3 concentrations as (e.g., Hausmann and Platt, 1994;Le Bras and Platt, 1995;Zeng et al, 2006;Stephens et al, 2012):…”

Section: Brox In Antarcticamentioning

confidence: 99%

Reactive bromine in the low troposphere of Antarctica. Estimations at two research sites

Prados-Román¹,

Gómez²,

Puentedura³

et al. 2018

Preprint

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Abstract.For decades, reactive halogen species (RHS) have been subject of detailed scientific research due to their influence on the 20 oxidizing capacity of the atmosphere and on the climate. From the RHS, those containing bromine are of particular interest in the polar troposphere as a result of their link to ozone depletion events (ODEs) and to the perturbation of the cycle of e.g. the toxic mercury. Given its remoteness and related limited accessibility compared to the Arctic region, the RHS in the Antarctic troposphere are still poorly characterized. This work presents ground-based observations of tropospheric BrO from two different Antarctic locations: Marambio (64º 13' S, 56º 37' W) and Belgrano II (77º 52' S, 34º 37' W) during the sunlit period 25 of 2015. By means of MAX-DOAS (Multi-axis Differential Optical Absorption Spectroscopy) measurements of BrO performed from the two research sites, the seasonal variation of this reactive trace gas is described along with its vertical and geographical distribution in the Antarctic environment. Results show an overall vertical profile of BrO mixing ratio decreasing with altitude, with a median value of 1.6 pmol mol -1 in the lowest layers of the troposphere and undetectable values above 2 km at both sites. Additionally, observations show that the polar sunrise triggers a heterogeneous increase of bromine content 30 in the Antarctic troposphere yielding a maximum BrO at Marambio (26 pmol mol -1 ), amounting threefold the values observed at Belgrano at dawn. Data presented herein are combined with previous studies and ancillary data to update and expand our knowledge of the geographical and vertical distribution of BrO in the Antarctic troposphere, revealing Marambio as one of the locations with highest BrO reported so far in Antarctica. Furthermore, the observations gathered during 2015 serve as a proxy to investigate the budget of reactive bromine (BrOx = Br + BrO) and the bromine-mediated ozone loss rate in the Antarctic 35 troposphere.

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Snowmelt onset hinders bromine monoxide heterogeneous recycling in the Arctic

et al. 2017

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Reactive bromine radicals (bromine atoms, Br, and bromine monoxide, BrO) deplete ozone and alter tropospheric oxidation chemistry during the Arctic springtime (February–June). As spring transitions to summer (May–June) and snow begins to melt, reactive bromine events cease and BrO becomes low in summer. In this study, we explore the relationship between the end of the reactive bromine season and snowmelt timing. BrO was measured by Multi‐AXis Differential Optical Absorption Spectrometer at Utqiaġvik (Barrow), AK, from 2012 to 2016 and on drifting buoys deployed in Arctic sea ice from 2011 to 2016, a total of 13 site and year combinations. The BrO seasonal end date (SED) was objectively determined and was compared to surface‐air‐temperature‐derived melt onset date (MOD). The SED was highly correlated with the MOD (N = 13, R2 = 0.983, RMS = 1.9 days), and BrO is only observed at subfreezing temperatures. In subsets of these sites and years where ancillary data were available, we observed that snowpack depth reduced and rain precipitation occurred within a few days of the SED. These data are consistent with snowpack melting hindering BrO recycling, which is necessary to maintain enhanced BrO concentrations. With a projected warmer Arctic, a shift to earlier snowmelt seasons could alter the timing and role of halogen chemical reactions in the Arctic with impacts on ozone depletion and mercury deposition.

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Temporal and spatial characteristics of ozone depletion events from measurements in the Arctic

Cited by 49 publications

References 93 publications

Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska

Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska

Reactive bromine in the low troposphere of Antarctica. Estimations at two research sites

Snowmelt onset hinders bromine monoxide heterogeneous recycling in the Arctic

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