scholarly journals Early unusual ozone loss during the Arctic winter 2002/2003 compared to other winters

2004 ◽  
Vol 4 (5) ◽  
pp. 5019-5044
Author(s):  
F. Goutail ◽  
J.-P. Pommereau ◽  
F. Lefèvre ◽  
M. Van Roozendael ◽  
S. B. Andersen ◽  
...  
Keyword(s):  
Low Temperature ◽  
The Arctic ◽  
Total Column Ozone ◽  
Ozone Loss ◽  
Column Ozone ◽  
Transport Method ◽  
Total Column ◽  
Very Low Temperature

Abstract. Total column ozone reduction in the Arctic is evaluated each winter since 1993/1994 by the transport method (3-D CTM passive ozone minus measurements). The cumulative loss from 1 December to the end of the season ranges from 5–10% during warm winters like 1998/1999, 2000/2001 and 2001/2002 up to 30%–32% during cold winters like 1994/1995 and 1995/1996. The 23% cumulative loss observed during the winter 2002/2003 is similar in amplitude to the 20–24% measured in 1996/1997 and 1999/2000 but the timing is different. It started unusually early in December after the occurrence of very low temperature at all stratospheric levels between 550 K and 435 K allowing PSC formation and thus chlorine activation. The early ozone loss of 2002/2003 is well captured by current 3-D CTM models.

scholarly journals Chemical ozone loss and ozone mini-hole event during the Arctic winter 2010/2011 as observed by SCIAMACHY and GOME-2

2014 ◽  
Vol 14 (7) ◽  
pp. 3247-3276 ◽  
Author(s):  
R. Hommel ◽  
K.-U. Eichmann ◽  
J. Aschmann ◽  
K. Bramstedt ◽  
M. Weber ◽  
...  
Keyword(s):  
Transport Model ◽  
Polar Vortex ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Late Winter ◽  
Total Column Ozone ◽  
Bromine Oxide ◽  
Ozone Loss ◽  
Catalytic Cycles ◽  
Total Column

Abstract. Record breaking loss of ozone (O3) in the Arctic stratosphere has been reported in winter–spring 2010/2011. We examine in detail the composition and transformations occurring in the Arctic polar vortex using total column and vertical profile data products for O3, bromine oxide (BrO), nitrogen dioxide (NO2), chlorine dioxide (OClO), and polar stratospheric clouds (PSC) retrieved from measurements made by SCIAMACHY (Scanning Imaging Absorption SpectroMeter for Atmospheric CHartography) on-board Envisat (Environmental Satellite), as well as total column ozone amount, retrieved from the measurements of GOME-2 (Global Ozone Monitoring Experiment) on MetOp-A (Meteorological Experimental Satellite). Similarly we use the retrieved data from DOAS (Differential Optical Absorption Spectroscopy) measurements made in Ny-Ålesund (78.55° N, 11.55° E). A chemical transport model (CTM) has been used to relate and compare Arctic winter–spring conditions in 2011 with those in the previous year. In late winter–spring 2010/2011 the chemical ozone loss in the polar vortex derived from SCIAMACHY observations confirms findings reported elsewhere. More than 70% of O3 was depleted by halogen catalytic cycles between the 425 and 525 K isentropic surfaces, i.e. in the altitude range ~16–20 km. In contrast, during the same period in the previous winter 2009/2010, a typical warm Arctic winter, only slightly more than 20% depletion occurred below 20 km, while 40% of O3 was removed above the 575 K isentrope (~23 km). This loss above 575 K is explained by the catalytic destruction by NOx descending from the mesosphere. In both Arctic winters 2009/2010 and 2010/2011, calculated O3 losses from the CTM are in good agreement to our observations and other model studies. The mid-winter 2011 conditions, prior to the catalytic cycles being fully effective, are also investigated. Surprisingly, a significant loss of O3 around 60%, previously not discussed in detail, is observed in mid-January 2011 below 500 K (~19 km) and sustained for approximately 1 week. The low O3 region had an exceptionally large spatial extent. The situation was caused by two independently evolving tropopause elevations over the Asian continent. Induced adiabatic cooling of the stratosphere favoured the formation of PSC, increased the amount of active chlorine for a short time, and potentially contributed to higher polar ozone loss later in spring.

scholarly journals Simple measures of ozone depletion in the polar stratosphere

2008 ◽  
Vol 8 (2) ◽  
pp. 251-264 ◽  
Author(s):  
R. Müller ◽  
J.-U. Grooß ◽  
C. Lemmen ◽  
D. Heinze ◽  
M. Dameris ◽  
...  
Keyword(s):  
Total Ozone ◽  
Climate Model ◽  
The Arctic ◽  
Total Column Ozone ◽  
Ozone Loss ◽  
Break Up ◽  
Column Ozone ◽  
The Impact ◽  
Polar Ozone ◽  
Daily Total

Abstract. We investigate the extent to which quantities that are based on total column ozone are applicable as measures of ozone loss in the polar vortices. Such quantities have been used frequently in ozone assessments by the World Meteorological Organization (WMO) and also to assess the performance of chemistry-climate models. The most commonly considered quantities are March and October mean column ozone poleward of geometric latitude 63° and the spring minimum of daily total ozone minima poleward of a given latitude. Particularly in the Arctic, the former measure is affected by vortex variability and vortex break-up in spring. The minimum of daily total ozone minima poleward of a particular latitude is debatable, insofar as it relies on one single measurement or model grid point. We find that, for Arctic conditions, this minimum value often occurs in air outside the polar vortex, both in the observations and in a chemistry-climate model. Neither of the two measures shows a good correlation with chemical ozone loss in the vortex deduced from observations. We recommend that the minimum of daily minima should no longer be used when comparing polar ozone loss in observations and models. As an alternative to the March and October mean column polar ozone we suggest considering the minimum of daily average total ozone poleward of 63° equivalent latitude in spring (except for winters with an early vortex break-up). Such a definition both obviates relying on one single data point and reduces the impact of year-to-year variability in the Arctic vortex break-up on ozone loss measures. Further, this measure shows a reasonable correlation (r=–0.75) with observed chemical ozone loss. Nonetheless, simple measures of polar ozone loss must be used with caution; if possible, it is preferable to use more sophisticated measures that include additional information to disentangle the impact of transport and chemistry on ozone.

scholarly journals Future Arctic ozone recovery: the importance of chemistry and dynamics

2016 ◽  
Author(s):  
E. M. Bednarz ◽  
A. C. Maycock ◽  
N. L. Abraham ◽  
P. Braesicke ◽  
O. Dessens ◽  
...  
Keyword(s):  
Polar Vortex ◽  
Lower Atmosphere ◽  
The Arctic ◽  
Relative Role ◽  
Total Column Ozone ◽  
The Future ◽  
Stratospheric Cooling ◽  
Column Ozone ◽  
Total Column

Abstract. Future trends in Arctic springtime total column ozone, and its chemical and dynamical drivers, are assessed using a 7 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 long-term mean to near present day values. Consistent with the global decline in inorganic chlorine (Cly) over the century, the estimated mean halogen induced chemical ozone loss in the Arctic lower atmosphere in spring decreases by around a factor of two between 1981-2000 and 2061-2080. However, in the presence of a cold and strong polar vortex elevated halogen losses well above the long-term mean continue to occur in the simulations into the second part of the century. The ensemble shows a radiatively-driven cooling trend modelled in the Arctic winter mid- and upper stratosphere, but there is less consistency across the seven ensemble members 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 years characterised by significantly suppressed downwelling, reduced transport and low temperatures continue into the future. We conclude that despite the future long-term recovery of Arctic ozone, the large interannual dynamical variability is expected to continue 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.

scholarly journals Assessing the Impact of Clouds on UV-visible Total Column Ozone Measurements in the High Arctic

2018 ◽  
Author(s):  
Xiaoyi Zhao ◽  
Kristof Bognar ◽  
Vitali Fioletov ◽  
Andrea Pazmino ◽  
Florence Goutail ◽  
...  
Keyword(s):  
The Arctic ◽  
Total Column Ozone ◽  
Random Uncertainty ◽  
Screening Algorithm ◽  
Cloudy Weather ◽  
Column Ozone ◽  
The Impact ◽  
Cloud Screening ◽  
Total Column

Abstract. Zenith-Sky scattered light Differential Optical Absorption Spectroscopy (ZS-DOAS) has been used widely to retrieve total column ozone (TCO). ZS-DOAS measurements have the advantage of being less sensitive to clouds than direct-sun measurements. However, the presence of clouds still affects the quality of ZS-DOAS TCO. Clouds are thought to be the largest contributor to random uncertainty in ZS-DOAS TCO, but their impact on data quality still needs to be quantified. This study has two goals: (1) to study whether clouds have a significant impact on ZS-DOAS TCO, and (2) to develop a cloud-screening algorithm to improve ZS-DOAS measurements in the Arctic under cloudy conditions. To quantify the impact of weather, eight years of measured and modelled TCO have been used, along with information about weather conditions at Eureka, Canada (80.05° N, 86.41° W). Relative to direct-sun TCO measurements by Brewer spectrophotometers and modelled TCO, a positive bias is found in ZS-DOAS TCO measured in cloudy weather, and a negative bias is found for clear conditions, with differences of up to 5 % between clear and cloudy conditions. A cloud-screening algorithm is developed for high-latitudes using the colour index calculated from ZS-DOAS spectra. The quality of ZS-DOAS TCO datasets is assessed using a statistical uncertainty estimation model, which suggests a 3–4 % random uncertainty. The new cloud-screening algorithm reduces the random uncertainty by 0.6 %. If all measurements collected during cloudy conditions, as identified using the weather station observations, are removed, the random uncertainty is reduced by 1.3 %. This work demonstrates that clouds are a significant contributor to uncertainty in ZS-DOAS TCO and proposes a method that can be used to screen clouds in high-latitude spectra.

scholarly journals An evaluation of the simulation of the edge of the Antarctic vortex by chemistry-climate models

2008 ◽  
Vol 8 (6) ◽  
pp. 20155-20192 ◽  
Author(s):  
H. Struthers ◽  
G. E. Bodeker ◽  
J. Austin ◽  
S. Bekki ◽  
I. Cionni ◽  
...  
Keyword(s):  
Climate Models ◽  
Measurement Data ◽  
Chemical Processes ◽  
Data Sets ◽  
Dynamical Structure ◽  
Total Column Ozone ◽  
Ozone Loss ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. The dynamical barrier to meridional mixing at the edge of the Antarctic spring stratospheric vortex is examined. Diagnostics are presented which demonstrate the link between the shape of the meridional mixing barrier at the edge of the vortex and the meridional gradients in total column ozone across the vortex edge. Results derived from reanalysis and measurement data sets are compared with equivalent diagnostics from five coupled chemistry-climate models to test how well the models capture the interaction between the dynamical structure of the stratospheric vortex and the chemical processes occurring within the vortex. Results show that the accuracy of the simulation of the dynamical vortex edge varies widely amongst the models studied here. This affects the ability of the models to simulate the large observed meridional gradients in total column ozone. Three of the models in this study simulated the inner edge of the vortex to be more than 7° closer to the pole than observed. This is expected to have important implications for how well these models simulate the extent of severe springtime ozone loss that occurs within the Antarctic vortex.

scholarly journals Stratospheric ozone loss in the Arctic winters between 2005 and 2013 derived with ACE-FTS measurements

2019 ◽  
Vol 19 (1) ◽  
pp. 577-601 ◽  
Author(s):  
Debora Griffin ◽  
Kaley A. Walker ◽  
Ingo Wohltmann ◽  
Sandip S. Dhomse ◽  
Markus Rex ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
The Arctic ◽  
Estimation Methods ◽  
Mixing Ratio ◽  
Total Column Ozone ◽  
Ozone Loss ◽  
Column Ozone ◽  
First Time

Abstract. Stratospheric ozone loss inside the Arctic polar vortex for the winters between 2004–2005 and 2012–2013 has been quantified using measurements from the space-borne Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). For the first time, an evaluation has been performed of six different ozone loss estimation methods based on the same single observational dataset to determine the Arctic ozone loss (mixing ratio loss profiles and the partial-column ozone losses between 380 and 550 K). The methods used are the tracer-tracer correlation, the artificial tracer correlation, the average vortex profile descent, and the passive subtraction with model output from both Lagrangian and Eulerian chemical transport models (CTMs). For the tracer-tracer, the artificial tracer, and the average vortex profile descent approaches, various tracers have been used that are also measured by ACE-FTS. From these seven tracers investigated (CH4, N2O, HF, OCS, CFC-11, CFC-12, and CFC-113), we found that CH4, N2O, HF, and CFC-12 are the most suitable tracers for investigating polar stratospheric ozone depletion with ACE-FTS v3.5. The ozone loss estimates (in terms of the mixing ratio as well as total column ozone) are generally in good agreement between the different methods and among the different tracers. However, using the average vortex profile descent technique typically leads to smaller maximum losses (by approximately 15–30 DU) compared to all other methods. The passive subtraction method using output from CTMs generally results in slightly larger losses compared to the techniques that use ACE-FTS measurements only. The ozone loss computed, using both measurements and models, shows the greatest loss during the 2010–2011 Arctic winter. For that year, our results show that maximum ozone loss (2.1–2.7 ppmv) occurred at 460 K. The estimated partial-column ozone loss inside the polar vortex (between 380 and 550 K) using the different methods is 66–103, 61–95, 59–96, 41–89, and 85–122 DU for March 2005, 2007, 2008, 2010, and 2011, respectively. Ozone loss is difficult to diagnose for the Arctic winters during 2005–2006, 2008–2009, 2011–2012, and 2012–2013, because strong polar vortex disturbance or major sudden stratospheric warming events significantly perturbed the polar vortex, thereby limiting the number of measurements available for the analysis of ozone loss.

scholarly journals Future Arctic ozone recovery: the importance of chemistry and dynamics

2016 ◽  
Vol 16 (18) ◽  
pp. 12159-12176 ◽  
Author(s):  
Ewa M. Bednarz ◽  
Amanda C. Maycock ◽  
N. Luke Abraham ◽  
Peter Braesicke ◽  
Olivier Dessens ◽  
...  
Keyword(s):  
Polar Vortex ◽  
Lower Atmosphere ◽  
The Arctic ◽  
Relative Role ◽  
Total Column Ozone ◽  
The Future ◽  
Stratospheric Cooling ◽  
Column Ozone ◽  
Total Column

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 (Cly) over the century, the estimated mean halogen-induced 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.

scholarly journals Simple measures of ozone depletion in the polar stratosphere

2007 ◽  
Vol 7 (4) ◽  
pp. 9829-9866
Author(s):  
R. Müller ◽  
J.-U. Grooß ◽  
C. Lemmen ◽  
D. Heinze ◽  
M. Dameris ◽  
...  
Keyword(s):  
Total Ozone ◽  
Climate Model ◽  
Grid Point ◽  
The Arctic ◽  
Monthly Means ◽  
Total Column Ozone ◽  
Ozone Loss ◽  
Column Ozone ◽  
The Impact ◽  
Polar Ozone

Abstract. We investigate the extent to which commonly considered quantities, based on total column ozone observations and simulations, are applicable as measures of ozone loss in the polar vortices. Such quantities have been used frequently in ozone assessments by the World Meteorological Organization (WMO) and to assess the performance of chemistry-climate models. The most commonly considered quantity is monthly mean column ozone poleward of a latitude of 63° in spring. For the Arctic, these monthly means were found to be insensitive to the exact choice of the latitude threshold, unlike the Antarctic where greater sensitivity was found. Choosing a threshold based on the location of the transport barrier at the vortex boundary instead of geometric latitude led to a roughly similar year-to-year variability of the monthly means, but in particular years deviations of several tens of Dobson units occurred. Moreover, the minimum of daily total ozone minima poleward of a particular latitude, another popular measure, is debatable, insofar as it relies on one single measurement or model grid point. For Arctic conditions, this minimum value occurred often in air outside polar vortex, both in the observations and in a chemistry-climate model. As a result, we recommend that the minimum of daily minima no longer be used when comparing polar ozone loss in observations and models. As a possible alternative, we suggest considering the minimum of daily average total ozone poleward of a particular equivalent latitude (or in the vortex) in spring. This definition both obviates relying on one single data point and reduces the impact of year-to-year variability in the Arctic vortex breakup on ozone loss measures. However, compact relations of such simple measures with meteorological quantities that describe the potential for polar heterogeneous chlorine activation and thus ozone loss were not found. Therefore, we argue that where possible, more sophisticated measures of chemical polar ozone loss that include additional information to disentangle the impact of transport and chemistry on ozone, should be employed.

scholarly journals Improvements to stratospheric chemistry scheme in the UM-UKCA (v10.7) model: solar cycle and heterogeneous reactions

2018 ◽  
Author(s):  
Fraser Dennison ◽  
James Keeble ◽  
Olaf Morgenstern ◽  
Guang Zeng ◽  
N. Luke Abraham ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Polar Vortex ◽  
Heterogeneous Reactions ◽  
The Arctic ◽  
Cold Bias ◽  
Total Column Ozone ◽  
Antarctic Polar Vortex ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. Improvements are made to two areas of the United Kingdom Chemistry and Aerosol (UKCA) module, which forms part of the Met Office Unified Model (UM) used for weather and climate applications. Firstly, a solar cycle is added to the photolysis scheme. The effect on total column ozone of this addition was found to be around 1–2 % in mid-latitude and equatorial regions in phase with the solar cycle. Secondly, reactions occurring on the surfaces of polar stratospheric clouds and sulfate aerosol are updated and extended by modification of the uptake coefficients of five existing reactions and the addition of a further eight reactions involving bromine species. These modifications are shown to reduce the overabundance of modeled total-column ozone in the Arctic during October to February, southern mid-latitudes during August, and the Antarctic during September. Antarctic springtime ozone depletion is shown to be enhanced by 25 DU on average, which now causes the ozone hole to be somewhat too deep compared to observations. We show that this is in part due to a cold bias of the Antarctic polar vortex in the model.

scholarly journals Stratospheric ozone loss in the Arctic winters between 2005 and 2013 derived with ACE-FTS measurements

2018 ◽  
Author(s):  
Debora Griffin ◽  
Kaley A. Walker ◽  
Ingo Wohltmann ◽  
Sandip S. Dhomse ◽  
Markus Rex ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Stratospheric Ozone ◽  
Correlation Method ◽  
Polar Vortex ◽  
The Arctic ◽  
Estimation Methods ◽  
Mixing Ratio ◽  
Total Column Ozone ◽  
Ozone Loss ◽  
Column Ozone

Abstract. Stratospheric ozone loss inside the Arctic polar vortex for the winters between 2004/2005 and 2012/2013 has been quantified using measurements from the space-borne Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). Six different methods, including tracer-tracer correlation, artificial tracer correlation, average vortex profile descent, and passive subtraction with model output from both Lagrangian and Eulerian chemical transport models (CTMs), have been employed to determine the Arctic ozone loss (mixing ratio loss profiles and the partial column ozone losses between 380 and 550 K). For the tracer-tracer, the artificial tracer, and the average vortex profile descent approaches, various tracers have been used. Here, we show that CH4, N2O, HF, and CFC-12 are suitable tracers for investigating polar stratospheric ozone depletion with ACE-FTS. The ozone loss estimates (in terms of the mixing ratio as well as total column ozone) are generally in good agreement between the different methods and among the different tracers. However, the tracer-tracer correlation method does not agree with the other estimation methods in March 2005 and using the average vortex profile descent technique typically leads to smaller maximum losses compared to all other methods. The passive subtraction method using output from CTMs generally results in smaller uncertainties and slightly larger losses compared to the techniques that use ACE-FTS measurements only. The ozone loss computed, using both measurements and models, shows the greatest loss during the 2010/2011 Arctic winter. For that year, our results show that maximum ozone loss (2.1–2.7 ppmv) occurred at 460 K. The estimated partial column ozone loss inside the polar vortex (between 380 K and 550 K) is 66–103 DU, 61–95 DU, 59–96 DU, 41–89 DU, and 85–122 DU for March 2005, 2007, 2008, 2010, and 2011, respectively. Ozone loss is difficult to diagnose during 2005/2006, 2008/2009, 2011/2012, and 2012/2013 because strong polar vortex disturbance or major sudden stratospheric warming events significantly perturbed the polar vortex thereby limiting the number of measurements available for the analysis.

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