scholarly journals An Arctic Ozone Hole in 2020 If Not For the Montreal Protocol

2021 ◽  
Author(s):  
Catherine Wilka ◽  
Susan Solomon ◽  
Doug Kinnison ◽  
David Tarasick
Keyword(s):  
Ozone Depletion ◽  
Total Ozone ◽  
Lower Stratosphere ◽  
Montreal Protocol ◽  
Ozone Hole ◽  
Boreal Spring ◽  
Polar Stratospheric Cloud ◽  
The Antarctic

Abstract. Without the Montreal Protocol the already extreme Arctic ozone losses in boreal spring of 2020 would be expected to have produced an Antarctic-like ozone hole, with an area of total ozone below 220 DU of about 20 million km2. Record observed local lows of 0.1 ppmv at some altitudes in the lower stratosphere would have reached 0.01, again similar to the Antarctic. This provides an opportunity to test parameterizations of polar stratospheric cloud impacts on denitrification, and thereby to improve stratospheric models. Spring ozone depletion would have begun earlier and lasted longer without the Montreal Protocol, and by 2020 the year-round ozone depletion would have begun to dramatically diverge from the observed case. This study reinforces that the historically extreme 2020 Arctic ozone depletion is not cause for concern over the Montreal Protocol's effectiveness, but rather demonstrates that the Montreal Protocol indeed merits celebration for avoiding an Arctic ozone hole.

scholarly journals Past and future conditions for polar stratospheric cloud formation simulated by the Canadian Middle Atmosphere Model

2009 ◽  
Vol 9 (2) ◽  
pp. 483-495 ◽  
Author(s):  
P. Hitchcock ◽  
T. G. Shepherd ◽  
C. McLandress
Keyword(s):  
Climate Change ◽  
Low Temperature ◽  
Ozone Depletion ◽  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
The Arctic ◽  
Temperature Extremes ◽  
Polar Stratospheric Cloud ◽  
Atmosphere Model ◽  
The Antarctic

Abstract. We analyze here the polar stratospheric temperatures in an ensemble of three 150-year integrations of the Canadian Middle Atmosphere Model (CMAM), an interactive chemistry-climate model which simulates ozone depletion and recovery, as well as climate change. A key motivation is to understand possible mechanisms for the observed trend in the extent of conditions favourable for polar stratospheric cloud (PSC) formation in the Arctic winter lower stratosphere. We find that in the Antarctic winter lower stratosphere, the low temperature extremes required for PSC formation increase in the model as ozone is depleted, but remain steady through the twenty-first century as the warming from ozone recovery roughly balances the cooling from climate change. Thus, ozone depletion itself plays a major role in the Antarctic trends in low temperature extremes. The model trend in low temperature extremes in the Arctic through the latter half of the twentieth century is weaker and less statistically robust than the observed trend. It is not projected to continue into the future. Ozone depletion in the Arctic is weaker in the CMAM than in observations, which may account for the weak past trend in low temperature extremes. In the future, radiative cooling in the Arctic winter due to climate change is more than compensated by an increase in dynamically driven downwelling over the pole.

scholarly journals 20 Years of ClO Measurements in the Antarctic Lower Stratosphere

2016 ◽  
Author(s):  
Gerald E. Nedoluha ◽  
Brian J. Connor ◽  
Thomas Mooney ◽  
James W. Barrett ◽  
Alan Parrish ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Montreal Protocol ◽  
Strong Increase ◽  
Interannual Variations ◽  
Strong Decrease ◽  
Chlorine Monoxide ◽  
Highly Correlated ◽  
The Antarctic ◽  
Underlying Trend ◽  
Wave Spectrometer

Abstract. We present 20 years of springtime measurements of ClO over Antarctica from the Chlorine monOxide Experiment (ChlOE1) ground-based millimeter wave spectrometer at Scott Base, Antarctica, as well 12 years of ClO measurements from the Aura Microwave Limb Sounder (MLS). From August onwards we observe a strong increase in lower stratospheric ClO, with a peak column amount usually occurring in early September. From mid-September onwards we observe a strong decrease in ClO. In order to study interannual differences we focus on a 3-week period from August 28 to September 17 for each year, and compare the average column ClO anomalies. These column ClO anomalies are shown to be highly correlated with the average ozone mass deficit for September and October of each year. We also show that anomalies in column ClO are anti-correlated with 30 hPa temperature anomalies, both on a daily and an interannual timescale. We calculate the dependence of interannual variations in column ClO on interannual variations in temperature. By making use of this relationship we can better estimate the underlying trend in the Cly which provides the reservoir for the ClO. The resultant trends for zonal MLS, Scott Base MLS (both 2004–2015), and ChlOE (1996–2015) were 0.5 ± 0.2 %/yr, −1.4 ± 0.9 %/yr, and −0.6 ± 0.4 %/yr, respectively. These trends are within 1σ of trends in stratospheric Cly previously found at other latitudes. This decrease in ClO is the result of changes in anthropogenic CFC emissions due to actions taken under the Montreal Protocol.

scholarly journals Effects of injected ice particles in the lower stratosphere on the Antarctic ozone hole

2015 ◽  
Vol 3 (5) ◽  
pp. 143-158 ◽  
Author(s):  
H. Nagase ◽  
D. E. Kinnison ◽  
A. K. Petersen ◽  
F. Vitt ◽  
G. P. Brasseur
Keyword(s):  
Lower Stratosphere ◽  
Ozone Hole ◽  
Ice Particles ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
Antarctic Ozone Hole

scholarly journals Dobson, Brewer, ERA-40 and ERA-Interim original and merged total ozone data sets – evaluation of differences: a case study, Hradec Králové (Czech), 1961–2010

2012 ◽  
Vol 4 (1) ◽  
pp. 91-100 ◽  
Author(s):  
K. Vaníček ◽  
L. Metelka ◽  
P. Skřivánková ◽  
M. Staněk
Keyword(s):  
Ozone Depletion ◽  
Total Ozone ◽  
Montreal Protocol ◽  
Data Series ◽  
Data Sets ◽  
Missing Measurements ◽  
Seasonal Differences ◽  
Ozone Data

Abstract. Homogenized data series of total ozone measurements taken by the regularly and well calibrated Dobson and Brewer spectrophotometers at Hradec Králové (Czech) and the data from the re-analyses ERA-40 and ERA-Interim were merged and compared to investigate differences between the particular data sets originated in Central Europe, the Northern Hemisphere (NH) mid-latitudes. The Dobson-to-Brewer transfer function and the algorithm for approximation of the data from the re-analyses were developed, tested and applied for creation of instrumentally consistent and completed total ozone data series of the 50-yr period 1961–2010 of observations. This correction has reduced the well-known seasonal differences between Dobson and Brewer data below the 1% calibration limit of the spectrophotometers. Incorporation of the ERA-40 and ERA-Interim total ozone data on days with missing measurements significantly improved completeness and reliability of the data series mainly in the first two decades of the period concerned. Consistent behaviour of the original and corrected/merged data sets was found in the pre-ozone-hole period (1961–1985). In the post-Pinatubo (1994–2010) era the data series show seasonal differences that can introduce uncertainty in estimation of ozone recovery mainly in the winter-spring season when the effect of the Montreal Protocol and its Amendments is expected. All the data sets confirm substantial depletion of ozone also in the summer months that gives rise to the question about its origin. The merged and completed data series of total ozone will be further analyzed to quantify chemical ozone losses and contribution of natural atmospheric processes to the ozone depletion over the region. This case study points out the importance of selection and evaluation of the quality and consistency of the input data sets used in estimation of long-term ozone changes including recovery of the ozone layer over the selected areas. Data are available from the PANGAEA database at doi:10.1594/PANGAEA.779819.

scholarly journals Mid-winter lower stratosphere temperatures in the Antarctic vortex: comparison between observations and ECMWF operational model.

2006 ◽  
Vol 6 (4) ◽  
pp. 7697-7714
Author(s):  
M. C. Parrondo ◽  
M. Yela ◽  
M. Gil ◽  
P. von der Gathen ◽  
H. Ochoa
Keyword(s):  
Ozone Depletion ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Temperature Fields ◽  
Temperature Profiles ◽  
Temperature Dependent ◽  
Operational Model ◽  
Weather Forecasts ◽  
Medium Range ◽  
The Antarctic

Abstract. Radiosonde temperature profiles from Belgrano (78° S) and other Antarctic stations have been compared with European Centre for Medium-Range Weather Forecasts (ECMWF) data during the winter of 2003. Results show a bias in the operational model which is height and temperature dependent, being too cold at layers peaking at 80 and 25–30 hPa, and hence resulting in an overestimation of the predicted potential PSC areas. Here we show the results of the comparison by considering the possibility of a bias in the sondes at extremely low temperatures and discuss the potential implications that this bias might have on the ozone depletion computed by Climate Transport Model based on ECMWF temperature fields.

scholarly journals Record low ozone values over the Arctic in boreal spring 2020

2021 ◽  
Vol 21 (2) ◽  
pp. 617-633
Author(s):  
Martin Dameris ◽  
Diego G. Loyola ◽  
Matthias Nützel ◽  
Melanie Coldewey-Egbers ◽  
Christophe Lerot ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Total Ozone ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Ozone Hole ◽  
The Arctic ◽  
Atmospheric Conditions ◽  
Total Ozone Column ◽  
The Antarctic ◽  
Ozone Column

Abstract. Ozone data derived from the Tropospheric Monitoring Instrument (TROPOMI) sensor on board the Sentinel-5 Precursor satellite show exceptionally low total ozone columns in the polar region of the Northern Hemisphere (Arctic) in spring 2020. Minimum total ozone column values around or below 220 Dobson units (DU) were seen over the Arctic for 5 weeks in March and early April 2020. Usually the persistence of such low total ozone column values in spring is only observed in the polar Southern Hemisphere (Antarctic) and not over the Arctic. These record low total ozone columns were caused by a particularly strong polar vortex in the stratosphere with a persistent cold stratosphere at higher latitudes, a prerequisite for ozone depletion through heterogeneous chemistry. Based on the ERA5, which is the fifth generation of the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis, the Northern Hemisphere winter 2019/2020 (from December to March) showed minimum polar cap temperatures consistently below 195 K around 20 km altitude, which enabled enhanced formation of polar stratospheric clouds. The special situation in spring 2020 is compared and discussed in context with two other Northern Hemisphere spring seasons, namely those in 1997 and 2011, which also displayed relatively low total ozone column values. However, during these years, total ozone columns below 220 DU over several consecutive days were not observed in spring. The similarities and differences of the atmospheric conditions of these three events and possible explanations for the observed features are presented and discussed. It becomes apparent that the monthly mean of the minimum total ozone column value for March 2020 (221 DU) was clearly below the respective values found in March 1997 (267 DU) and 2011 (252 DU), which highlights the special evolution of the polar stratospheric ozone layer in the Northern Hemisphere in spring 2020. A comparison with a typical ozone hole over the Antarctic (e.g., in 2016) indicates that although the Arctic spring 2020 situation is remarkable, with total ozone column values around or below 220 DU observed over a considerable area (up to 0.9 million km2), the Antarctic ozone hole shows total ozone columns typically below 150 DU over a much larger area (of the order of 20 million km2). Furthermore, total ozone columns below 220 DU are typically observed over the Antarctic for about 4 months.

scholarly journals The Antarctic ozone hole during 2015 and 2016

2019 ◽  
Vol 69 (1) ◽  
pp. 16
Author(s):  
Matthew B. Tully ◽  
Andrew R. Klekociuk ◽  
Paul B. Krummel ◽  
H. Peter Gies ◽  
Simon P. Alexander ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Ozone Depletion ◽  
Volcanic Eruption ◽  
Stratospheric Aerosol ◽  
Satellite Observations ◽  
Ozone Hole ◽  
Maximum Area ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
Antarctic Ozone Hole

We reviewed the 2015 and 2016 Antarctic ozone holes, making use of a variety of ground-based and spacebased measurements of ozone and ultraviolet radiation, supplemented by meteorological reanalyses. The ozone hole of 2015 was one of the most severe on record with respect to maximum area and integrated deficit and was notably longlasting, with many values above previous extremes in October, November and December. In contrast, all assessed metrics for the 2016 ozone hole were at or below their median values for the 37 ozone holes since 1979 for which adequate satellite observations exist. The 2015 ozone hole was influenced both by very cold conditions and enhanced ozone depletion caused by stratospheric aerosol resulting from the April 2015 volcanic eruption of Calbuco (Chile).

scholarly journals A major event of Antarctic ozone hole influence in southern Brazil in October 2016: an analysis of tropospheric and stratospheric dynamics

2018 ◽  
Vol 36 (2) ◽  
pp. 415-424 ◽  
Author(s):  
Gabriela Dornelles Bittencourt ◽  
Caroline Bresciani ◽  
Damaris Kirsch Pinheiro ◽  
José Valentin Bageston ◽  
Nelson Jorge Schuch ◽  
...  
Keyword(s):  
Total Ozone ◽  
Ozone Hole ◽  
Ozone Content ◽  
Southern Brazil ◽  
Pressure System ◽  
Air Mass ◽  
Stratospheric Dynamics ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
Antarctic Ozone Hole

Abstract. The Antarctic ozone hole is a cyclical phenomenon that occurs during the austral spring where there is a large decrease in ozone content in the Antarctic region. Ozone-poor air mass can be released and leave through the Antarctic ozone hole, thus reaching midlatitude regions. This phenomenon is known as the secondary effect of the Antarctic ozone hole. The objective of this study is to show how tropospheric and stratospheric dynamics behaved during the occurrence of this event. The ozone-poor air mass began to operate in the region on 20 October 2016. A reduction of ozone content of approximately 23 % was observed in relation to the climatology average recorded between 1992 and 2016. The same air mass persisted over the region and a drop of 19.8 % ozone content was observed on 21 October. Evidence of the 2016 event occurred through daily mean measurements of the total ozone column made with a surface instrument (Brewer MkIII no. 167 Spectrophotometer) located at the Southern Space Observatory (29.42∘ S, 53.87∘ W) in São Martinho da Serra, Rio Grande do Sul. Tropospheric dynamic analysis showed a post-frontal high pressure system on 20 and 21 October 2016, with pressure levels at sea level and thickness between 1000 and 500 hPa. Horizontal wind cuts at 250 hPa and omega values at 500 hPa revealed the presence of subtropical jet streams. When these streams were allied with positive omega values at 500 hPa and a high pressure system in southern Brazil and Uruguay, the advance of the ozone-poor air mass that caused intense reductions in total ozone content could be explained. Keywords. Atmospheric composition and structure (middle atmosphere – composition and chemistry)

Polar ozone depletion: Current status

1991 ◽  
Vol 69 (8-9) ◽  
pp. 1110-1122 ◽  
Author(s):  
G. S. Henderson ◽  
J. C. McConnell ◽  
S. R. Beagley ◽  
W. F. J. Evans
Keyword(s):  
High Latitude ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Chemical Mechanism ◽  
The Arctic ◽  
Current Status ◽  
Austral Spring ◽  
The Antarctic ◽  
Polar Ozone

Rapid springtime depletion of column ozone (O3) is observed over the Antarctic during the austral spring. A much weaker springtime depletion is observed in the Arctic region. This depletion results from a complex chemical mechanism that involves the catalytic destruction of stratospheric ozone by chlorine. The chemical mechanism appears to operate between ~12–25 km in the colder regions of the polar winter vortices. During the polar night heterogeneous chemical reactions occur on the surface of polar stratospheric clouds that convert relatively inert reservoir Cl species such as HCl to active Cl species. These clouds form when temperatures drop below about 197 K and are ubiquitous throughout the polar winter region. At polar sunrise the reactive Cl species are photolysed, liberating large quantities of free Cl that subsequently catalytically destroys O3 with a mechanism involving the formation of the Cl2O2 dimer. The magnitude of the spring depletion is much greater in the Antarctic relative to the Arctic owing to the greater stability and longer duration of the southern polar vortex. Breakup of the intense high-latitude vortices in late (Antarctic) or early (Arctic) spring results in infilling of the ozone holes but adversely affects midlatitude ozone levels by diluting them with O3-depleted, ClO-rich high-latitude air. The magnitude of the Antarctic ozone depletion has been increasing since 1979 and its current depletion in October 1990 amounts to 60%. The increase in the size of the depletion is anticorrelated with increasing anthropogenic chlorofluorocarbon (CFCs) release. Adherence to the revised Montréal Protocol should result in a reduction of stratospheric halogen levels with subsequent amelioration of polar ozone depletion but the time constant for the atmosphere to return to pre-CFC levels is ~60–100 years.

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