The effect of climate change on ozone depletion through changes in stratospheric water vapour (original) (raw)
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Chemical Loss of Ozone in the Arctic Polar Vortex in the Winter of 1991-1992
Science, 1993
The H, O trend is estimated by calculating the difference between the average H20 with the H, O residual estimated in K. Kelly et a/. [Geophys. Res. Lett. 17, 465 (1989)], and scaling with the CH, trend. The H20 difference is a result of CH, oxidation in the stratosphere. 17. The HNO, trend is estimated by assuming that the NO, trend is the same as the N, O trend (0 2%) and using the scaling of NO, (10). 18. Projected injections of NO, and H, O are taken from scenario F in M. Prather et a/. [NASA Ref. Publ. 1272 (1992)l. In this report, NO is estimated to increase 4 ppbv and H, O will rncrease by about 1 ppmv, for an emission index of 15 and a Mach number 3.2. 19. T. Peter et a/. [Geophys. Res. Lett. 18, 1465 (1991)l calculated a doubling of the PSC probability for future fleets of stratospheric aircraft (a 1.7 K increase in the 50-hPa NAT saturation temperature using a two-dimensional chemistry model). 20. We thank all the partic~pants in the AASE II mission.
The potential for ozone depletion in the Arctic polar stratosphere
Science, 1991
The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (HCl and ClONO,) was converted by reactions on polar stratospheric clouds to reactive ClO and C1202 throughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO,, and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15% at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8% losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50% over the next two decades, ozone losses recognizable as an ozone hole may well appear.
Journal of Geophysical Research, 1996
Chlorine-catalyzed ozone destruction is clearly observed during austral spring in the Antarctic lower stratosphere. While high concentrations of ozone-destroying C10 radicals have likewise been measured during winter in the Arctic stratosphere, the chemical ozone depletion there is more difficult to quantify. Here we present observations of the Halogen Occultation Experiment on the Upper Atmosphere Research Satellite in the vortex region of the Arctic lower stratosphere during the winter and spring months of measurements indicate an almost complete conversion of the otherwise main chlorine reservoir species HC1 to chemically more reactive forms. Using CH4 as a chemically conserved tracer, we show that significant chemical ozone loss occurred in the Arctic vortex region during all four winters. The deficit in column ozone was about 60 and 50 Dobson units (DU) in the winters 1991/1992 and 1993/1994, respectively. During the two winters of 1992/1993 and 1994/1995 a severe chemical loss in lower-stratospheric ozone took place, with local reductions of the mixing ratios by over 50% and a loss in the column ozone of the order of 100 DU. al., 1990, 1993] albeit to a much smaller extent than over Antarctica. Recent observations [Larsen et al., 1994; Manney et al., 1994a] indicate a particularly strong ozone loss in the Arctic vortex for early 1993. 1Now at In the Arctic, dynamical processes cause considerable ozone variations, making chemical ozone depletion more difficult to quantify than for the Antarctic. A high-pressure system in the troposphere causes a high tropopause, cold temperatures, and a low total ozone column in the lower stratosphere [Dobson et al., 1929; McKenna et al., 1989; Poole et al., 1990; Petzoldt et al., 1994]. On the other hand, 12,531
Future polar ozone - predictions of Arctic ozone recovery in a changing climate
2005
Possible recovery of the polar stratospheric ozone layer has previously been assessed with a variety of chemistry climate models (CCMs). With a decreasing load of ozonedepleting substances (ODS), a recovery of Antarctic ozone columns to pre-1980 conditions is expected somewhere around 2050, while Arctic ozone is predicted to recover much earlier. This hemispheric difference is due to the generally warmer and more disturbed North Polar winter vortex. It is unclear, however, whether the net effect of Climate Change leads to a cooling or warming of the Arctic winter polar vortex. It is uncertain, how increasing amounts of greenhouse gases affect the evolution of the ozone layer, which is tightly coupled to the prevailing stratospheric temperature through the formation of polar stratospheric clouds. On the one hand, the North Polar stratosphere is projected to warm due to additional energy dissipated by planetary and gravity waves. These waves are triggered by tropospheric meteorology, which may be influenced by ongoing climatic changes, for example, regional changes in surface temperatures. On the other hand, the radiative effect of most greenhouse gases which leads to a warmer troposphere cools higher atmospheric layers. Cloud formation depends critically on threshold temperatures, and activation of ODS depends on the availability of surfaces provided by cloud particles. The prediction of Arctic polar ozone with climate models is difficult given the complex interactions of climate change, stratospheric temperature and ozone depletion. In this thesis, based on a multi-annual CCM time slice experiment with year 2015 boundary conditions, deficiencies, analysis methods and improvements for the assessment of future polar ozone loss are examined. The chemistry transport model CLaMS is employed in combination with the tracer-tracer correlation technique. Dynamical changes to the 2015 ozone column are isolated from chemical changes. Updates to CCM results for springtime Arctic minimum ozone columns and new results for maximum ozone loss columns for 2015 conditions are presented. Recommendations for verification of ozone loss chemistry and the calculation of chemical ozone loss are provided for post-analysis of already performed CCM simulations. CLaMS simulations show that around 2015 northern hemispheric ozone depletion may be as severe as observed and modelled in medium to cold 1990s winters: at 19 km altitude, up to 1.85 ppm chemical ozone loss is predicted in the polar vortex. Chemical column ozone depletion of 85 Dobson units (DU) is found, while corresponding CCM results show less than 50% of this loss. The apparent recovery of Arctic ozone in the CCM is attributed to dynamical changes rather than decreased stratospheric halogen loading. The new prediction for the 2015 springtime minimal ozone column is 250 DU as opposed to 296 DU found by the CCM alone; from this analysis, there is no indication for Arctic ozone recovery within the next decade.
Arctic winter 2005: Implications for stratospheric ozone loss and climate change
Geophysical Research Letters, 2006
1] The Arctic polar vortex exhibited widespread regions of low temperatures during the winter of 2005, resulting in significant ozone depletion by chlorine and bromine species. We show that chemical loss of column ozone (DO 3 ) and the volume of Arctic vortex air cold enough to support the existence of polar stratospheric clouds (V PSC ) both exceed levels found for any other Arctic winter during the past 40 years. Cold conditions and ozone loss in the lowermost Arctic stratosphere (e.g., between potential temperatures of 360 to 400 K) were particularly unusual compared to previous years. Measurements indicate DO 3 = 121 ± 20 DU and that DO 3 versus V PSC lies along an extension of the compact, near linear relation observed for previous Arctic winters. The maximum value of V PSC during five to ten year intervals exhibits a steady, monotonic increase over the past four decades, indicating that the coldest Arctic winters have become significantly colder, and hence are more conducive to ozone depletion by anthropogenic halogens. Citation: Rex, M., et al. (2006), Arctic winter 2005: Implications for stratospheric ozone loss and climate change, Geophys. Res. Lett., 33, L23808,
Atmospheric Chemistry and Physics, 2004
Chemical ozone loss in the Arctic stratosphere was investigated for the twelve years between 1991 and 2003 employing the ozone-tracer correlation method. For this method, the change in the relation between ozone and a longlived tracer is considered for all twelve years over the lifetime of the polar vortex to calculate chemical ozone loss. Both the accumulated local ozone loss in the lower stratosphere and the column ozone loss were derived consistently, mainly on the basis of HALOE satellite observations. HALOE measurements do not cover the polar region homogeneously over the course of the winter. Thus, to derive an early winter reference function for each of the twelve years, all available measurements were additionally used; for two winters climatological considerations were necessary. Moreover, a detailed quantification of uncertainties was performed. This study further demonstrates the interaction between meteorology and ozone loss. The connection between temperature conditions and chlorine activation, and in turn, the connection between chlorine activation and ozone loss, becomes obvious in the HALOE HCl measurements. Additionally, the degree of homogeneity of ozone loss within the vortex was shown to depend on the meteorological conditions. Results derived here are in general agreement with the results obtained by other methods for deducing polar ozone loss. Differences occur mainly owing to different time periods considered in deriving accumulated ozone loss. However, very strong ozone losses as deduced from SAOZ for January in winters 1993-1994 and 1995-1996 cannot be identified using available HALOE observations in the early winter. In general, strong accumulated ozone loss was found to occur in conjunction with a strong cold vortex containing a large volume of possible PSC existence (V PSC), whereas moderate ozone loss was found if the vortex was less strong and moderately warm. Hardly any ozone loss was calculated
A review of surface ozone in the polar regions
Atmospheric Environment, 2007
Surface ozone records from ten polar research stations were investigated for the depend-19 encies of ozone on radiative processes, snow-photochemisty, and synoptic and stratospheric 20 transport. A total of 146 annual data records for the Arctic sites Barrow, Alaska; Summit, 21
Atmospheric Chemistry and Physics, 2010
Most of the ozone loss (60-75%) at this level results from nitrogen catalytic cycles rather than halogen cycles. At both 475 and 675 K levels the simulated ozone and ozone loss evolution inside the vortex is in reasonably good agreement with the MLS observations. The ozone partial column loss in 350-850 K deduced from the model calculations at the MLS sampling locations inside the polar vortex ranges between 43 DU in 2005/2006 and 109 DU in 2004/2005, while those derived from the MLS observations range between 26 DU and 115 DU for the same winters. The partial column ozone depletion derived in that vertical range is larger than that estimated in 350-550 K by 19±7 DU on average, mainly due to NO x chemistry. The column ozone loss estimates from both Mimosa-Chim and MLS in 350-850 K are generally in good agreement with those derived from ground-based ultravioletvisible spectrometer total ozone observations for the respective winters, except in 2010.
Chemical depletion of Arctic ozone in winter 1999/2000
Journal of Geophysical Research, 2002
1] During Arctic winters with a cold, stable stratospheric circulation, reactions on the surface of polar stratospheric clouds (PSCs) lead to elevated abundances of chlorine monoxide (ClO) that, in the presence of sunlight, destroy ozone. Here we show that PSCs were more widespread during the 1999/2000 Arctic winter than for any other Arctic winter in the past two decades. We have used three fundamentally different approaches to derive the degree of chemical ozone loss from ozonesonde, balloon, aircraft, and satellite instruments. We show that the ozone losses derived from these different instruments and approaches agree very well, resulting in a high level of confidence in the results. Chemical processes led to a 70% reduction of ozone for a region $1 km thick of the lower stratosphere, the largest degree of local loss ever reported for the Arctic. The Match analysis of ozonesonde data shows that the accumulated chemical loss of ozone inside the Arctic vortex totaled 117 ± 14 Dobson units (DU) by the end of winter. This loss, combined with dynamical redistribution of air parcels, resulted in a 88 ± 13 DU reduction in total column ozone compared to the amount that would have been present in the JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. D20, 8276,