scholarly journals How sensitive is the recovery of stratospheric ozone to changes in concentrations of very short-lived bromocarbons?

2014 ◽  
Vol 14 (19) ◽  
pp. 10431-10438 ◽  
Author(s):  
X. Yang ◽  
N. L. Abraham ◽  
A. T. Archibald ◽  
P. Braesicke ◽  
J. Keeble ◽  
...  
Keyword(s):  
Climate Model ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Background Concentrations ◽  
Future Situation ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
The Impact ◽  
Ozone Column ◽  
Policy Question

Abstract. Naturally produced very short-lived substances (VSLS) account for almost a quarter of the current stratospheric inorganic bromine, Bry. Following VSLS oxidation, bromine radicals (Br and BrO) can catalytically destroy ozone. The extent to which possible increases in surface emissions or transport of these VSLS bromocarbons to the stratosphere could counteract the effect of halogen reductions under the Montreal Protocol is an important policy question. Here, by using a chemistry–climate model, UM-UKCA, we investigate the impact of a hypothetical doubling (an increase of 5 ppt Bry) of VSLS bromocarbons on ozone and how the resulting ozone changes depend on the background concentrations of chlorine and bromine. Our model experiments indicate that for the 5 ppt increase in Bry from VSLS, the ozone decrease in the lowermost stratosphere of the Southern Hemisphere (SH) may reach up to 10% in the annual mean; the ozone decrease in the Northern Hemisphere (NH) is smaller (4–6%). The largest impact on the ozone column is found in the Antarctic spring. There is a significantly larger ozone decrease following the doubling of the VSLS burden under a high stratospheric chlorine background than under a low chlorine background, indicating the importance of the inter-halogen reactions. For example, the decline in the high-latitude, lower-stratospheric ozone concentration as a function of Bry is higher by about 30–40% when stratospheric Cly is ~ 3 ppb (present day), compared with Cly of ~ 0.8 ppb (a pre-industrial or projected future situation). Bromine will play an important role in the future ozone layer. However, even if bromine levels from natural VSLS were to increase significantly later this century, changes in the concentration of ozone will likely be dominated by the decrease in anthropogenic chlorine. Our calculation suggests that for a 5 ppt increase in Bry from VSLS, the Antarctic ozone hole recovery date could be delayed by approximately 6–8 years, depending on Cly levels.

scholarly journals How sensitive is the recovery of stratospheric ozone to changes in concentrations of very short lived bromocarbons?

2014 ◽  
Vol 14 (7) ◽  
pp. 9729-9745 ◽  
Author(s):  
X. Yang ◽  
N. L. Abraham ◽  
A. T. Archibald ◽  
P. Braesicke ◽  
J. Keeble ◽  
...  
Keyword(s):  
Climate Model ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Background Concentrations ◽  
Ozone Loss ◽  
Future Situation ◽  
Antarctic Ozone ◽  
Rate Of Decline ◽  
The Antarctic ◽  
The Impact

Abstract. Naturally produced very short-lived substances (VSLS), like bromocarbons, account for almost a quarter of the current stratospheric inorganic bromine, Bry. Following VSLS oxidation, bromine radicals (Br and BrO) can catalytically destroy ozone. The extent to which possible increases in surface emissions or transport of these VSLS bromocarbons to the stratosphere could counteract the effect of halogen reductions under the Montreal Protocol is an important policy question. Here by using a chemistry–climate model, UM-UKCA, we investigate the impact of a hypothetical increase in VSLS on ozone and how that impact depends on the background concentrations of chlorine and bromine. Our model experiments indicate that for a ~5 ppt increase in Bry from VSLS, the local ozone loss in the lowermost stratosphere of the Southern Hemisphere (SH) may reach up to 10% in the annual mean; the ozone loss in the Northern Hemisphere (NH) is smaller (4–6%). There is more ozone loss following an increase in VSLS burden under a high stratospheric chlorine background than under a low chlorine background indicating the importance of the inter-halogen reactions. For example, the rate of decline of the stratospheric ozone concentration as a function of Bry is higher by about 30–40% when stratospheric Cly is ~3 ppb (present day) compared with Cly of ~0.8 ppb (apre-industrial or projected future situation). Although bromine plays an important role in destroying ozone, inorganic chlorine is the dominant halogen compound. Even if bromine levels from natural VSLS were to increase significantly later this century, changes in the concentration of ozone will be dominated by the recovery of anthropogenic chlorine. Our calculation suggests that for a 5 ppt increase in Bry from VSLS, the Antarctic ozone hole recover date could be delayed by approximately 7 years.

scholarly journals Impact of biogenic very short-lived bromine on the Antarctic ozone hole during the 21<sup>st</sup> century

2016 ◽  
Author(s):  
Rafael P. Fernandez ◽  
Douglas E. Kinnison ◽  
Jean-Francois Lamarque ◽  
Simone Tilmes ◽  
Alfonso Saiz-Lopez
Keyword(s):  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Ozone Hole ◽  
Hole Area ◽  
Climate Simulations ◽  
Photochemical Decomposition ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
The Impact ◽  
Antarctic Ozone Hole

Abstract. Active bromine released from the photochemical decomposition of biogenic very short-lived bromocarbons (VSLBr) enhances stratospheric ozone depletion. Based on a dual set of 1960–2100 coupled chemistry-climate simulations (i.e. with and without VSLBr), we show that the maximum Antarctic ozone hole depletion increases by up to 14 % when natural VSLBr are considered, in better agreement with ozone observations. The impact of the additional 5 pptv VSLBr on Antarctic ozone is most evident in the periphery of the ozone hole, producing an expansion of the ozone hole area of ~5 million km2, which is equivalent in magnitude to the recently estimated Antarctic ozone healing due to the implementation of the Montreal Protocol. We find that the inclusion of VSLBr in CAM-Chem does not introduce a significant delay of the modelled ozone return date to 1980 October levels, but instead affect the depth and duration of the simulated ozone hole. Our analysis further shows that total bromine-catalysed ozone destruction in the lower stratosphere surpasses that of chlorine by year 2070, and indicates that natural VSLBr chemistry would dominate Antarctic ozone seasonality before the end of the 21st century. This work suggests a large influence of biogenic bromine on the future Antarctic ozone layer.

Atmospheric impacts of short-lived chlorinated species over the recent past: a chemistry-climate perspective

2021 ◽  
Author(s):  
Ewa Bednarz ◽  
Ryan Hossaini ◽  
Luke Abraham ◽  
Peter Braesicke ◽  
Martyn Chipperfield
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Lower Boundary ◽  
Montreal Protocol ◽  
Recent Past ◽  
Substantial Impact ◽  
Ozone Depleting Substances ◽  
The Impact

&lt;p&gt;The emissions of most long-lived halogenated ozone-depleting substances (ODSs) are now decreasing, owing to controls on their production introduced by Montreal Protocol and its amendments. However, short-lived halogenated compounds can also have substantial impact on atmospheric chemistry, including stratospheric ozone, particularly if emitted near climatological uplift regions. It has recently become evident that emissions of some chlorinated very short-lived species (VSLSs), such as chloroform (CHCl&lt;sub&gt;3&lt;/sub&gt;) and dichloromethane (CH&lt;sub&gt;2&lt;/sub&gt;Cl&lt;sub&gt;2&lt;/sub&gt;), could be larger than previously believed and increasing, particularly in Asia. While these may exert a significant influence on atmospheric chemistry and climate, their impacts remain poorly characterised.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We address this issue using the UM-UKCA chemistry-climate model (CCM). While not only the first, to our knowledge, model study addressing this problem using a CCM, it is also the first such study employing a whole atmosphere model, thereby simulating the tropospheric Cl-VSLSs emissions and the resulting stratospheric impacts in a fully consistent manner. We use a newly developed Double-Extended Stratospheric-Tropospheric (DEST) chemistry scheme, which includes emissions of all major chlorinated and brominated VSLSs alongside an extended treatment of long-lived ODSs.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We examine the impacts of rising Cl-VSLSs emissions on atmospheric chlorine tracers and ozone, including their long-term trends. We pay particular attention to the role of &amp;#8216;nudging&amp;#8217;, as opposed to the free-running model set up, for the simulated Cl-VSLSs impacts, thereby demostrating the role of atmospheric dynamics in modulating the atmospheric responses to Cl-VSLSs. In addition, we employ novel estimates of Cl-VSLS emissions over the recent past and compare the results with the simulations that prescribe Cl-VSLSs using simple lower boundary conditions. This allows us to demonstrate the impact such choice has on the dominant location and seasonality of the Cl-VSLSs transport into the stratosphere.&lt;/p&gt;

scholarly journals Impact of biogenic very short-lived bromine on the Antarctic ozone hole during the 21st century

2017 ◽  
Vol 17 (3) ◽  
pp. 1673-1688 ◽  
Author(s):  
Rafael P. Fernandez ◽  
Douglas E. Kinnison ◽  
Jean-Francois Lamarque ◽  
Simone Tilmes ◽  
Alfonso Saiz-Lopez
Keyword(s):  
21St Century ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Ozone Hole ◽  
Community Atmosphere Model ◽  
Hole Area ◽  
Photochemical Decomposition ◽  
Antarctic Ozone ◽  
The Impact ◽  
Antarctic Ozone Hole

Abstract. Active bromine released from the photochemical decomposition of biogenic very short-lived bromocarbons (VSLBr) enhances stratospheric ozone depletion. Based on a dual set of 1960–2100 coupled chemistry–climate simulations (i.e. with and without VSLBr), we show that the maximum Antarctic ozone hole depletion increases by up to 14 % when natural VSLBr are considered, which is in better agreement with ozone observations. The impact of the additional 5 pptv VSLBr on Antarctic ozone is most evident in the periphery of the ozone hole, producing an expansion of the ozone hole area of ∼ 5 million km2, which is equivalent in magnitude to the recently estimated Antarctic ozone healing due to the implementation of the Montreal Protocol. We find that the inclusion of VSLBr in CAM-Chem (Community Atmosphere Model with Chemistry, version 4.0) does not introduce a significant delay of the modelled ozone return date to 1980 October levels, but instead affects the depth and duration of the simulated ozone hole. Our analysis further shows that total bromine-catalysed ozone destruction in the lower stratosphere surpasses that of chlorine by the year 2070 and indicates that natural VSLBr chemistry would dominate Antarctic ozone seasonality before the end of the 21st century. This work suggests a large influence of biogenic bromine on the future Antarctic ozone layer.

scholarly journals Nadir ozone profile retrieval from SCIAMACHY and its application to the Antarctic ozone hole in the period 2003–2011

2017 ◽  
Author(s):  
Sweta Shah ◽  
Olaf Tuinder ◽  
Jacob van Peet ◽  
Adrianus de Laat ◽  
Piet Stammes
Keyword(s):  
Spectral Response ◽  
Stratospheric Ozone ◽  
Ozone Hole ◽  
Retrieval Algorithm ◽  
Latitude Range ◽  
Ozone Profile ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
Ozone Column ◽  
Antarctic Ozone Hole

Abstract. The depletion of the Antarctic ozone layer and its changing vertical distribution has been monitored closely by satellites in the past decades ever since the Antarctic ozone hole was discovered in the 1980's. Ozone profile retrieval from nadir-viewing satellites operating in the ultraviolet-visible range requires accurate calibration of level-1 (L1) radiance data. Here we study the effects of calibration on the derived level-2 (L2) ozone profiles and apply the retrieval to the Antarctic ozone hole region. We retrieve nadir ozone profiles from the SCIAMACHY instrument that flew on-board Envisat using the Ozone ProfilE Retrieval Algorithm) (OPERA) developed at KNMI with a focus on the stratospheric ozone. We study and assess the quality of these profiles and compare retrieved (L2) products from L1 SCIAMACHY versions 7 and 8 indicated as respectively (v7, v8) data from the years 2003–2011 without further radiometric correction. From validation of the profiles against ozone sonde measurements, we find that the v8 performs better due to correction for the scan-angle dependency of the instrument's optical degradation. The instrument spectral response function can still be improved for the L1 v8 data with a shift and squeeze. We find that the contribution from this improvement is a few percent residue reduction compared to a reference in the solar irradiance spectra. Validation for the years 2003 and 2009 with ozone sondes shows deviations of SCIAMACHY ozone profiles of 0.8 %–15 % in the stratosphere and 2.5 %–100 % in the troposphere, depending on the latitude and the L1 version used. Using L1 v8 for the years 2003–2011 leads to deviations of ~ 1 %–11 % in stratospheric ozone and ~ 1 %–45 % in tropospheric ozone. Application of SCIAMACHY v8 data on the Antarctic ozone hole shows that most ozone is depleted in the latitude range from 70° S to 90° S. The minimum integrated ozone column consistently occurs around 15 September for the years 2003–2011. Furthermore from the ozone profiles for all these years we observe that the value of ozone column per layer reduces to almost zero at a pressure of 100 hPa in the latitude range of 70° S to 90° S, as was found from other observations.

Improved characterisation of the impact of chlorinated VSLSs on atmospheric chemistry and climate: past, present and future

2020 ◽  
Author(s):  
Ewa Bednarz ◽  
Ryan Hossaini ◽  
Luke Abraham ◽  
Martyn Chipperfield
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Recent Past ◽  
Substantial Impact ◽  
Emissions Scenarios ◽  
Ozone Depleting Substances ◽  
The Impact ◽  
Future Emissions

&lt;p&gt;The emissions of most long-lived halogenated ozone-depleting substances (ODSs) are now decreasing, owing to controls on their production introduced by Montreal Protocol and its amendments. However, short-lived halogenated compounds can also have substantial impact on atmospheric chemistry, including stratospheric ozone, particularly if emitted near climatological uplift regions. It has recently become evident that emissions of some chlorinated very short-lived species (VSLSs), such as chloroform (CHCl&lt;sub&gt;3&lt;/sub&gt;) and dichloromethane (CH&lt;sub&gt;2&lt;/sub&gt;Cl&lt;sub&gt;2&lt;/sub&gt;), could be larger than previously believed and increasing, particularly in Asia. While these may exert a significant influence on atmospheric chemistry and climate, their impacts remain poorly characterised.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We address this issue using the UM-UKCA chemistry-climate model. We use a newly developed Double-Extended Stratospheric-Tropospheric (DEST) chemistry scheme, which includes emissions of all major chlorinated and brominated VSLSs alongside an extended treatment of long-lived ODSs. Employing novel estimates of Cl-VSLS emissions we show model results regarding the atmospheric impacts of chlorinated VSLSs over the recent past (2000-present), with a focus on stratospheric ozone and HCl trends. Finally, we introduce our plans regarding examining the impacts of chlorinated VSLSs under a range of potential future emissions scenarios; the results of which will be directly relevant for the next WMO/UNEP assessment.&lt;/p&gt;

scholarly journals Delay in recovery of the Antarctic ozone hole from unexpected CFC-11 emissions

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
S. S. Dhomse ◽  
W. Feng ◽  
S. A. Montzka ◽  
R. Hossaini ◽  
J. Keeble ◽  
...  
Keyword(s):  
Montreal Protocol ◽  
Ozone Hole ◽  
Atmospheric Variability ◽  
Gas Emissions ◽  
Model Simulations ◽  
The Future ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
The Impact ◽  
Antarctic Ozone Hole

AbstractThe Antarctic ozone hole is decreasing in size but this recovery will be affected by atmospheric variability and any unexpected changes in chlorinated source gas emissions. Here, using model simulations, we show that the ozone hole will largely cease to occur by 2065 given compliance with the Montreal Protocol. If the unusual meteorology of 2002 is repeated, an ozone-hole-free-year could occur as soon as the early 2020s by some metrics. The recently discovered increase in CFC-11 emissions of ~ 13 Gg yr−1 may delay recovery. So far the impact on ozone is small, but if these emissions indicate production for foam use much more CFC-11 may be leaked in the future. Assuming such production over 10 years, disappearance of the ozone hole will be delayed by a few years, although there are significant uncertainties. Continued, substantial future CFC-11 emissions of 67 Gg yr−1 would delay Antarctic ozone recovery by well over a decade.

scholarly journals Antarctic ozone hole modifies iodine geochemistry on the Antarctic Plateau

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Andrea Spolaor ◽  
François Burgay ◽  
Rafael P. Fernandez ◽  
Clara Turetta ◽  
Carlos A. Cuevas ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Ice Core ◽  
Iodine Concentration ◽  
Ozone Hole ◽  
Antarctic Plateau ◽  
Climate Model Simulations ◽  
The Antarctic ◽  
The Impact

AbstractPolar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica. The effects of the ozone hole and the associated increase in incoming UV radiation on terrestrial and marine ecosystems are well established; however, the impact on geochemical cycles of ice photoactive elements, such as iodine, remains mostly unexplored. Here, we present the first iodine record from the inner Antarctic Plateau (Dome C) that covers approximately the last 212 years (1800-2012 CE). Our results show that the iodine concentration in ice remained constant during the pre-ozone hole period (1800-1974 CE) but has declined twofold since the onset of the ozone hole era (~1975 CE), closely tracking the total ozone evolution over Antarctica. Based on ice core observations, laboratory measurements and chemistry-climate model simulations, we propose that the iodine decrease since ~1975 is caused by enhanced iodine re-emission from snowpack due to the ozone hole-driven increase in UV radiation reaching the Antarctic Plateau. These findings suggest the potential for ice core iodine records from the inner Antarctic Plateau to be as an archive for past stratospheric ozone trends.

scholarly journals The representation of solar cycle signals in stratospheric ozone. Part II: Analysis of global models

2017 ◽  
Author(s):  
Amanda C. Maycock ◽  
Katja Matthes ◽  
Susann Tegtmeier ◽  
Hauke Schmidt ◽  
Rémi Thiéblemont ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Solar Irradiance ◽  
Climate Models ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Temperature Response ◽  
Solar Variability ◽  
High Latitudes ◽  
Stratospheric Temperature ◽  
The Impact

Abstract. The impact of changes in incoming solar irradiance on stratospheric ozone abundances should be included in climate model simulations to fully capture the atmospheric response to solar variability. This study presents the first systematic comparison of the solar-ozone response (SOR) during the 11 year solar cycle amongst different chemistry-climate models (CCMs) and ozone databases specified in climate models that do not include chemistry. We analyse the SOR in eight CCMs from the WCRP/SPARC Chemistry-Climate Model Initiative (CCMI-1) and compare these with three ozone databases: the Bodeker Scientific database, the SPARC/AC&amp;C database for CMIP5, and the SPARC/CCMI database for CMIP6. The results reveal substantial differences in the representation of the SOR between the CMIP5 and CMIP6 ozone databases. The peak amplitude of theSOR in the upper stratosphere (1–5 hPa) decreases from 5 % to 2 % between the CMIP5 and CMIP6 databases. This difference is because the CMIP5 database was constructed from a regression model fit to satellite observations, whereas the CMIP6 database is constructed from CCM simulations, which use a spectral solar irradiance (SSI) dataset with relatively weak UV forcing. The SOR in the CMIP6 ozone database is therefore implicitly more similar to the SOR in the CCMI-1 models than to the CMIP5 ozone database, which shows a greater resemblance in amplitude and structure to the SOR in the Bodeker database. The latitudinal structure of the annual mean SOR in the CMIP6 ozone database and CCMI-1 models is considerably smoother than in the CMIP5 database, which shows strong gradients in the SOR across the midlatitudes owing to the paucity of observations at high latitudes. The SORs in the CMIP6 ozone database and in the CCMI-1 models show a strong seasonal dependence, including large meridional gradients at mid to high latitudes during winter; such seasonal variations in the SOR are not included in the CMIP5 ozone database. Sensitivity experiments with a global atmospheric model without chemistry (ECHAM6.3) are performed to assess the impact of changes in the representation of the SOR and SSI forcing between CMIP5 and CMIP6. The experiments show that the smaller amplitude of the SOR in the CMIP6 ozone database compared to CMIP5 causes a decrease in the modelled tropical stratospheric temperature response over the solar cycle of up to 0.6 K, or around 50 % of the total amplitude. The changes in the SOR explain most of the difference in the amplitude of the tropical stratospheric temperature response in the case with combined changes in SOR and SSI between CMIP5 and CMIP6. The results emphasise the importance of adequately representing the SOR in climate models to capture the impact of solar variability on the atmosphere. Since a number of limitations in the representation of the SOR in the CMIP5 ozone database have been identified, CMIP6 models without chemistry are encouraged to use the CMIP6 ozone database to capture the climate impacts of solar variability.

scholarly journals Evolution of Antarctic ozone in September–December predicted by CCMVal-2 model simulations for the 21st century

2013 ◽  
Vol 13 (8) ◽  
pp. 4413-4427 ◽  
Author(s):  
J. M. Siddaway ◽  
S. V. Petelina ◽  
D. J. Karoly ◽  
A. R. Klekociuk ◽  
R. J. Dargaville
Keyword(s):  
21St Century ◽  
Climate Model ◽  
Polar Vortex ◽  
Early Summer ◽  
Slow Increase ◽  
Large Variability ◽  
Model Simulations ◽  
Antarctic Ozone ◽  
Decadal Rate ◽  
The Antarctic

Abstract. Chemistry-Climate Model Validation phase 2 (CCMVal-2) model simulations are used to analyze Antarctic ozone increases in 2000–2100 during local spring and early summer, both vertically integrated and at several pressure levels in the lower stratosphere. Multi-model median trends of monthly zonal mean total ozone column (TOC), ozone volume mixing ratio (VMR), wind speed and temperature poleward of 60° S are investigated. Median values are used to account for large variability in models, and the associated uncertainty is calculated using a bootstrapping technique. According to the trend derived from the twelve CCMVal-2 models selected, Antarctic TOC will not return to a 1965 baseline, an average of 1960–1969 values, by the end of the 21st century in September–November, but will return in ~2080 in December. The speed of December ozone depletion before 2000 was slower compared to spring months, and thus the decadal rate of December TOC increase after 2000 is also slower. Projected trends in December ozone VMR at 20–100 hPa show a much slower rate of ozone recovery, particularly at 50–70 hPa, than for spring months. Trends in temperature and winds at 20–150 hPa are also analyzed in order to attribute the projected slow increase of December ozone and to investigate future changes in the Antarctic atmosphere in general, including some aspects of the polar vortex breakup.

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