The impact of the mixing properties within the Antarctic stratospheric vortex on ozone loss in spring

Lee, Adrian M.; Roscoe, H. K.; Jones, A. E.; Haynes, P. H.; Shuckburgh, Emily; Morrey, Martin; Pumphrey, Hugh C.

doi:10.1029/2000jd900398

Cited by 72 publications

(88 citation statements)

References 30 publications

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“…As we have mentioned before, this ozone reduction is caused by transport of ozone-depleted air from lower latitudes where the ozone depletion had already started. The delay observed on SPS is a result of the time the ozone-poor air takes to travel from 78 to 90 • S according to Lee et al (2001). These observational results are in excellent agreement with the evolution of losses versus latitude and time computed by the SLIMCAT 3-D chemical-transport model for the year 1996 and 480 K isentropic level (Lee et al, 2001).…”

Section: Ozone Distribution Within the Vortex: Belgrano Vs South Polesupporting

confidence: 77%

“…The delay observed on SPS is a result of the time the ozone-poor air takes to travel from 78 to 90 • S according to Lee et al (2001). These observational results are in excellent agreement with the evolution of losses versus latitude and time computed by the SLIMCAT 3-D chemical-transport model for the year 1996 and 480 K isentropic level (Lee et al, 2001). Moreover, the model also shows that accumulated ozone loss becomes equal at a equivalent latitude poleward of 74 • S by the beginning of October, as found in the observations.…”

Section: Ozone Distribution Within the Vortex: Belgrano Vs South Polementioning

confidence: 99%

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Antarctic ozone variability inside the polar vortex estimated from balloon measurements

et al. 2014

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Abstract. Thirteen years of ozone soundings at the Antarctic Belgrano II station (78 • S, 34.6 • W) have been analysed to establish a climatology of stratospheric ozone and temperature over the area. The station is inside the polar vortex during the period of development of chemical ozone depletion. Weekly periodic profiles provide a suitable database for seasonal characterization of the evolution of stratospheric ozone, especially valuable during wintertime, when satellites and ground-based instruments based on solar radiation are not available. The work is focused on ozone loss rate variability (August-October) and its recovery (NovemberDecember) at different layers identified according to the severity of ozone loss. The time window selected for the calculations covers the phase of a quasi-linear ozone reduction, around day 220 (mid-August) to day 273 (end of September). Decrease of the total ozone column over Belgrano during spring is highly dependent on the meteorological conditions. Largest depletions (up to 59 %) are reached in coldest years, while warm winters exhibit significantly lower ozone loss (20 %). It has been found that about 11 % of the total O 3 loss, in the layer where maximum depletion occurs, takes place before sunlight has arrived, as a result of transport to Belgrano of air from a somewhat lower latitude, near the edge of the polar vortex, providing evidence of mixing inside the vortex. Spatial homogeneity of the vortex has been examined by comparing Belgrano results with those previously obtained for South Pole station (SPS) for the same altitude range and for 9 yr of overlapping data. Results show more than 25 % higher ozone loss rate at SPS than at Belgrano. The behaviour can be explained taking into account (i) the transport to both stations of air from a somewhat lower latitude, near the edge of the polar vortex, where sunlight reappears sooner, resulting in earlier depletion of ozone, and (ii) the accumulated hours of sunlight, which become much greater at the South Pole after the spring equinox. According to the variability of the ozone hole recovery, a clear connection between the timing of the breakup of the vortex and the monthly ozone content was found. Minimum ozone concentration of 57 DU in the 12-24 km layer remained in November, when the vortex is more persistent, while in years when the final stratospheric warming took place "very early", mean integrated ozone rose by up to 160-180 DU.

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Section: Ozone Distribution Within the Vortex: Belgrano Vs South Polesupporting

confidence: 77%

Section: Ozone Distribution Within the Vortex: Belgrano Vs South Polementioning

confidence: 99%

Antarctic ozone variability inside the polar vortex estimated from balloon measurements

et al. 2014

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“…Kawa et al [1997] have used aircraft observations in the vortex edge to show that reactive Cl is very sensitive to temperatures near 195 K. Midwinter temperatures at the vortex edge (60°S) are about 200 K, while the vortex center (80°-90°S) typically has temperatures below 190 K. A zonally symmetric ozone hole of 25 million km 2 would be at 64.4°S. Lee et al [2001] have shown that the polar vortex at 480 K is separated into a well-mixed zone in the equivalent latitude range of 70°-90°S, and a weakly mixed zone of approximately 60°-70°S. The hole edge is most sensitive to temperature and chemistry in this ''weakly'' mixed region.…”

Section: Dynamical Variationsmentioning

confidence: 99%

“…These stations are chosen because their observations were made in the Lee et al [2001] ''weakly'' mixed region. The 50-day diabatic trajectories are run using UKMO analyses.…”

Section: Trajectory and Chemistry Modelingmentioning

confidence: 99%

On the size of the Antarctic ozone hole

Newman

Kawa

Nash

2004

Geophysical Research Letters

104

114

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[1] A primary estimate of the severity of the Antarctic ozone hole is its size. The size is calculated from the area contained by total column ozone values less than 220 Dobson Units (DU) during September -October. The 220-DU value is used because it is lower than pre-1980 observed ozone values, and because it is in the strong ozone gradient region. We quantitatively show that the ozone hole size is primarily sensitive to effective stratospheric chlorine trends, and secondarily to the year-to-year variations in temperatures near the edge of the polar vortex. Temperatures are in turn sensitive to variations in tropospheric planetary wave forcing of the Southern Hemisphere stratosphere. Currently the average hole size reaches approximately 25 million km 2 each spring. Slow decreases of ozone depleting substances will only result in a decrease of about 1 million km 2 by 2015. This slow size decrease will be obscured by large dynamically forced year-to-year variations of 4 million km 2 (1s), and possibly delayed by greenhouse gas cooling of the Antarctic stratosphere.

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“…5b), align with the outer limits of regions of enhanced ozone loss (Lee et al, 2001;Bodeker et al, 2002). This provides motivation for updated analyses of trends in vortex attributes, such as BI, to provide context for recent reports of trends in ozone concentrations observed during September (e.g.…”

Section: Impacts Of Bifurcated Pv Gradientsmentioning

confidence: 63%

Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex

2018

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Abstract. The wintertime stratospheric westerly winds circling the Antarctic continent, also known as the Southern Hemisphere polar vortex, create a barrier to mixing of air between middle and high latitudes. This dynamical isolation has important consequences for export of ozone-depleted air from the Antarctic stratosphere to lower latitudes. The prevailing view of this dynamical barrier has been an annulus compromising steep gradients of potential vorticity (PV) that create a single semi-permeable barrier to mixing. Analyses presented here show that this barrier often displays a bifurcated structure where a double-walled barrier exists. The bifurcated structure manifests as enhanced gradients of PV at two distinct latitudes -usually on the inside and outside flanks of the region of highest wind speed. Metrics that quantify the bifurcated nature of the vortex have been developed and their variation in space and time has been analysed. At most isentropic levels between 395 and 850 K, bifurcation is strongest in mid-winter and decreases dramatically during spring. From August onwards a distinct structure emerges, where elevated bifurcation remains between 475 and 600 K, and a mostly single-walled barrier occurs at other levels. While bifurcation at a given level evolves from month to month, and does not always persist through a season, interannual variations in the strength of bifurcation display coherence across multiple levels in any given month. Accounting for bifurcation allows the region of reduced mixing to be better characterised. These results suggest that improved understanding of cross-vortex mixing requires consideration of the polar vortex not as a single mixing barrier but as a barrier with internal structure that is likely to manifest as more complex gradients in trace gas concentrations across the vortex barrier region.

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The impact of the mixing properties within the Antarctic stratospheric vortex on ozone loss in spring

Cited by 72 publications

References 30 publications

Antarctic ozone variability inside the polar vortex estimated from balloon measurements

Antarctic ozone variability inside the polar vortex estimated from balloon measurements

On the size of the Antarctic ozone hole

Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex

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