Temperature thresholds for  chlorine activation and ozone loss in the polar stratosphere

Drdla, K.; Müller, Rolf

doi:10.5194/angeo-30-1055-2012

Cited by 90 publications

(131 citation statements)

References 131 publications

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“…Nonetheless, they represent the first long-term, vortex-wide 15 observational-based record of SAD and VD and can be used to compare CALIOP stratospheric data with in situ particle measurements and to test parameterizations of the chemical and radiative effects of particles in current and future theoretical models. Since the SAD and VD estimates cover the full range of CALIOP data, including "sub-visible" PSCs as well as background aerosols, they may prove especially valuable in studies of the role of PSCs relative to that of cold background aerosols in early-season chlorine activation (e.g., Wegner et al, 2016;Drdla and Müller, 2012). 20…”

Section: Particle Surface Area Density and Volume Densitymentioning

confidence: 99%

Polar stratospheric cloud climatology based on CALIPSO spaceborne lidar measurements from 2006–2017

Pitts¹,

Poole²,

Gonzalez³

2018

Preprint

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Section: Particle Surface Area Density and Volume Densitymentioning

confidence: 99%

Polar stratospheric cloud climatology based on CALIPSO spaceborne lidar measurements from 2006–2017

Pitts¹,

Poole²,

Gonzalez³

2018

Preprint

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“…The relative roles and temperature dependencies of surface reactions on and in water ice, nitric acid trihydrate ice, and supercooled liquid sulfuric acid−water−nitric acid and binary sulfuric acid−water particles at background levels have been research topics since the late 1980s, and some important questions have recently reemerged. Some recent studies have suggested that heterogeneous chemistry taking place on background particles of sulfuric acid and water is sufficient to explain nearly all of the chlorine activation (17)(18)(19) and ozone losses in both the Arctic and Antarctic (17) without any need for temperatures below −78°C or formation of polar stratospheric clouds, which would represent a major change in understanding. The potential for liquid binary aerosols to play some role in ozone loss under cold conditions was first identified decades ago (20,21).…”

Section: Lower Stratospheric Chemistrymentioning

confidence: 99%

Fundamental differences between Arctic and Antarctic ozone depletion

Solomon

Haskins

Ivy

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Antarctic ozone depletion is associated with enhanced chlorine from anthropogenic chlorofluorocarbons and heterogeneous chemistry under cold conditions. The deep Antarctic "hole" contrasts with the generally weaker depletions observed in the warmer Arctic. An unusually cold Arctic stratospheric season occurred in 2011, raising the question of how the Arctic ozone chemistry in that year compares with others. We show that the averaged depletions near 20 km across the cold part of each pole are deeper in Antarctica than in the Arctic for all years, although 2011 Arctic values do rival those seen in less-depleted years in Antarctica. We focus not only on averages but also on extremes, to address whether or not Arctic ozone depletion can be as extreme as that observed in the Antarctic. This information provides unique insights into the contrasts between Arctic and Antarctic ozone chemistry. We show that extreme Antarctic ozone minima fall to or below 0.1 parts per million by volume (ppmv) at 18 and 20 km (about 70 and 50 mbar) whereas the lowest Arctic ozone values are about 0.5 ppmv at these altitudes. At a higher altitude of 24 km (30-mbar level), no Arctic data below about 2 ppmv have been observed, including in 2011, in contrast to values more than an order of magnitude lower in Antarctica. The data show that the lowest ozone values are associated with temperatures below −80°C to −85°C depending upon altitude, and are closely associated with reduced gaseous nitric acid concentrations due to uptake and/or sedimentation in polar stratospheric cloud particles.stratosphere | atmospheric chemistry T he extensive springtime depletion of Antarctic ozone has attracted both public and scientific interest since its discovery (1) and explanation in the 1980s. The ozone hole has been linked to the coupling of human-made chlorofluorocarbons with surface chemistry on and in polar stratospheric clouds (PSCs) that form during extreme cold conditions (2). Polar stratospheric clouds are composed of nitric acid hydrates, liquid solutions of sulfuric acid, water, and nitric acid, and (under very cold conditions) water ice (e.g., ref. 3 and citations therein). Some of the key reactions are photochemical, so that the ozone hole does not form during midwinter when the polar cap is dark, but rather in late winter/spring as sunlight returns, provided that temperatures remain low. Although the same basic chemical mechanisms operate in both hemispheres, the Arctic winter stratosphere is generally warmer than the Antarctic, and it warms up earlier in the spring. These two factors taken together explain why ozone depletion in the Arctic is generally much smaller than in the Antarctic. A particularly cold Arctic stratospheric winter and spring in 2010/2011 displayed much larger ozone depletion than typical years, as highlighted by Manney et al. (4). This noteworthy geophysical event has intrigued scientists and raised several important questions: Could this be the first Arctic ozone hole? Are Arctic ozone losses ever observed to be as extreme...

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“…In addition to PSCs, chlorine activation can also occur on cold sulfate aerosols (e.g. Hanson et al, 1994;Drdla and Müller, 2012;Wegner et al, 2012;Solomon et al, 2015). In contrast, a warmer, more disturbed polar vortex should be accompanied by much smaller chemical destruction of ozone and enhanced transport from lower latitudes.…”

Section: Introductionmentioning

confidence: 99%

Future Arctic ozone recovery: the importance of chemistry and dynamics

et al. 2016

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Abstract. Future trends in Arctic springtime total column ozone, and its chemical and dynamical drivers, are assessed using a seven-member ensemble from the Met Office Unified Model with United Kingdom Chemistry and Aerosols (UM-UKCA) simulating the period 1960-2100. The Arctic mean March total column ozone increases throughout the 21st century at a rate of ∼ 11.5 DU decade −1 , and is projected to return to the 1980 level in the late 2030s. However, the integrations show that even past 2060 springtime Arctic ozone can episodically drop by ∼ 50-100 DU below the corresponding long-term ensemble mean for that period, reaching values characteristic of the near-present-day average level. Consistent with the global decline in inorganic chlorine (Cl y ) over the century, the estimated mean halogeninduced chemical ozone loss in the Arctic lower atmosphere in spring decreases by around a factor of 2 between the periods 2001-2020 and 2061-2080. However, in the presence of a cold and strong polar vortex, elevated halogen-induced ozone losses well above the corresponding long-term mean continue to occur in the simulations into the second part of the century. The ensemble shows a significant cooling trend in the Arctic winter mid-and upper stratosphere, but there is less confidence in the projected temperature trends in the lower stratosphere (100-50 hPa). This is partly due to an increase in downwelling over the Arctic polar cap in winter, which increases transport of ozone into the polar region as well as drives adiabatic warming that partly offsets the radiatively driven stratospheric cooling. However, individual winters characterised by significantly suppressed downwelling, reduced transport and anomalously low temperatures continue to occur in the future. We conclude that, despite the projected long-term recovery of Arctic ozone, the large interannual dynamical variability is expected to continue in the future, thereby facilitating episodic reductions in springtime ozone columns. Whilst our results suggest that the relative role of dynamical processes for determining Arctic springtime ozone will increase in the future, halogen chemistry will remain a smaller but non-negligible contributor for many decades to come.

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Temperature thresholds for chlorine activation and ozone loss in the polar stratosphere

Cited by 90 publications

References 131 publications

Polar stratospheric cloud climatology based on CALIPSO spaceborne lidar measurements from 2006–2017

Polar stratospheric cloud climatology based on CALIPSO spaceborne lidar measurements from 2006–2017

Fundamental differences between Arctic and Antarctic ozone depletion

Future Arctic ozone recovery: the importance of chemistry and dynamics

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