Record low ozone values over the Arctic in boreal spring 2020

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.

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First description and classification of the ozone hole over the Arctic in boreal spring 2020

10.5194/acp-2020-746 ◽

2020 ◽

Author(s):

Martin Dameris ◽

Diego G. Loyola ◽

Matthias Nützel ◽

Melanie Coldewey-Egbers ◽

Christophe Lerot ◽

...

Keyword(s):

Northern Hemisphere ◽

Total Ozone ◽

Stratospheric Ozone ◽

Ozone Hole ◽

The Arctic ◽

Atmospheric Conditions ◽

Total Ozone Column ◽

Boreal Spring ◽

Ozone Column

Abstract. Ozone data derived from the TROPOMI sensor onboard the Sentinel-5 Precursor satellite are showing an atypical ozone hole feature in the polar region of the Northern hemisphere (Arctic) in spring 2020. A persistent ozone hole pattern with minimum total ozone column values around or below 220 Dobson units (DU) was seen for the first time over the Arctic for about 5 weeks in March and early April 2020. Usually an ozone hole with such low total ozone column values has only been observed in the polar Southern hemisphere (Antarctic) in spring over the last 4 decades, but not over the Arctic. The ozone hole pattern was caused by a particularly stable polar vortex in the stratosphere, enabling a persistent cold stratosphere at higher latitudes, a prerequisite for ozone depletion through heterogeneous chemistry. Based on the ERA5 reanalysis from ECMWF, the Northern 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 ozone hole-like features in spring 1997 and 2011 that were showing comparable dynamical conditions in the stratosphere in combination with low total ozone column values. However, during these years total ozone columns below 220 DU over larger areas and over several consecutive days have not been observed. The similarities and differences of the atmospheric conditions of these three events and possible explanations are presented and discussed. It becomes apparent that the monthly mean of the minimum total ozone column value for March 2020 (i.e. 221 DU) was clearly below the respective values found in March 1997 (i.e. 267 DU) and 2011 (i.e. 252 DU), which emphasizes the noteworthiness of the evolution of the polar stratospheric ozone layer in Northern hemisphere spring 2020. These results provide a first description and classification of the development of the Arctic ozone hole in boreal spring 2020 and highlight its peculiarity.

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The January 2006 low ozone event over the UK

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-6-8457-2006 ◽

2006 ◽

Vol 6 (5) ◽

pp. 8457-8483 ◽

Cited By ~ 2

Author(s):

M. Keil ◽

D. R. Jackson ◽

M. C. Hort

Keyword(s):

Total Ozone ◽

Stratospheric Ozone ◽

Polar Vortex ◽

British Isles ◽

Stratospheric Polar Vortex ◽

North West ◽

Total Ozone Column ◽

Mixing Ratios ◽

The Uk ◽

Ozone Column

Abstract. A record low total ozone column of 177 DU was observed at Reading, UK, on 19 January 2006. Low ozone values were also recorded at other stations in the British Isles and North West Europe on, and around, this date. Hemispheric maps of total ozone from the World Meteorological Organisation (WMO) Ozone Mapping Centre also show the evolution of this ozone minimum from 15–20 January 2006 over North West Europe. Ozonesonde measurements made at Lerwick, UK, show that ozone mixing ratios in the mid-stratosphere on 18 January are around 1–2 ppmv lower than both climatology and observations made one and two weeks prior to this date. In addition, ozone mixing ratios in the UTLS region were also noticeably reduced on 18 January. Analysis of the ozonesonde observations indicate that the mid-stratosphere ozone accounts for around a third of the reduction in total ozone column measurements while the UTLS ozone values account for two thirds of the depletion. It is evident from the ozonesonde data that ozone loss is occuring at two distinct vertical regions. Met Office analyses indicate that stratospheric polar vortex temperatures were cold enough for Polar Stratospheric Cloud (PSC) formation during 14 days in January prior to the low ozone event on 19 January. The presence of PSCs is confirmed by observations from the Scanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY). As a consequence of a stratospheric sudden warming that was in progress during January 2006, the polar vortex was shifted southwards over northwest Europe. This includes a period from 16 to 19 January where PSCs were present in the vortex over the UK. Throughout most of January suitable conditions were present for ozone destruction by heterogenous chemistry within the polar vortex. Evidence from Lerwick and Sodankylä ozonesonde profiles, and maps of Ertel's potential vorticity calculated from Met Office analyses, strongly suggests that the air inside the stratospheric vortex was poor in ozone for at least one week prior to 18 January. It is also possible that local chemical destruction of stratospheric ozone further contributed to the record low ozone observed at Reading. A closer examination of the WMO total ozone maps shows that the daily minima are often of synoptic, rather than planetary, scale. This therefore suggests a tropospheric, rather than stratospheric, mechanism for the ozone minima. Moderate total ozone depletion is commonly observed in the northern hemisphere middle and high latitude winter. This depletion is related to the lifting of the tropopause associated with the presence of an upper troposphere/lower stratosphere anticyclone. We show a strong link between the ozone minima in the WMO maps and 100 hPa geopotential height from Met Office analyses, and therefore it appears that this may also be a plausible mechanism for the record low ozone column that is observed. Back trajectories calculated by the Met Office NAME III model show that air parcels in the mid-stratosphere do arrive over the British Isles on 19 January via the polar vortex. The NAME III model results also show that air parcels near the tropopause arrive from low latitudes and are transported anticyclonically. Therefore this strongly suggests that the record low ozone values are due to a combination of a raised tropopause and the presence of low ozone stratospheric air aloft.

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Chemical ozone loss in Arctic and Antarctic polar winter/spring season derived from SCIAMACHY limb measurements 2002–2009

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-6555-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 6555-6599 ◽

Cited By ~ 8

Author(s):

T. Sonkaew ◽

C. von Savigny ◽

K.-U. Eichmann ◽

M. Weber ◽

A. Rozanov ◽

...

Keyword(s):

Mass Loss ◽

Total Ozone ◽

Stratospheric Ozone ◽

Polar Vortex ◽

The Arctic ◽

Absorption Bands ◽

Data Set ◽

Ozone Loss ◽

The Difference ◽

The Antarctic

Abstract. Stratospheric ozone profiles are retrieved for the period 2002–2009 from SCIAMACHY measurements of limb-scattered solar radiation in the Hartley and Chappuis absorption bands of ozone. This data set is used to determine the chemical ozone loss in both the Arctic and Antarctic polar vortices using the vortex average method. The chemical ozone loss at isentropic levels between 450 K and 600 K is derived from the difference between observed ozone abundances and the ozone modelled considering diabatic cooling, but no chemical ozone loss. The results show chemical ozone losses of up to 20–40% between the beginning of January and the end of March inside the Arctic polar vortex. Strong inter-annual variability of the Arctic ozone loss is observed, with the cold winters 2004/2005 and 2006/2007 showing the largest chemical ozone losses. The ozone mass loss inside the polar vortex is also estimated. In the coldest Arctic winter 2004/2005 the total ozone mass loss is about 30 million tons inside the polar vortex between the 450 K and 600 K isentropic levels from the beginning of January until the end of March. The Antarctic vortex averaged ozone loss as well as the size of the polar vortex do not vary much from year to year. At the 475 K isentropic level ozone losses of 70–80% between mid-August and mid-November are observed every year inside the vortex, also in the anomalous year 2002. The total ozone mass loss inside the Antarctic polar vortex between the 450 K and 600 K isentropic levels is about 55–75 million tons for the period between mid-August and mid-November. Comparisons of the vertical variation of ozone loss derived from SCIAMACHY observations with several independent techniques for the Arctic winter 2004/2005 show very good agreement.

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Solar UV radiation measurements in Marambio, Antarctica, during years 2017–2019

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-6037-2020 ◽

2020 ◽

Vol 20 (10) ◽

pp. 6037-6054

Author(s):

Margit Aun ◽

Kaisa Lakkala ◽

Ricardo Sanchez ◽

Eija Asmi ◽

Fernando Nollas ◽

...

Keyword(s):

Uv Radiation ◽

Total Ozone ◽

Cloud Cover ◽

Stratospheric Ozone ◽

Polar Vortex ◽

Early Summer ◽

Finnish Meteorological Institute ◽

Total Ozone Column ◽

Uv Irradiance ◽

Ozone Column

Abstract. In March 2017, measurements of downward global irradiance of ultraviolet (UV) radiation were started with a multichannel GUV-2511 radiometer in Marambio, Antarctica (64.23∘ S; 56.62∘ W), by the Finnish Meteorological Institute (FMI) in collaboration with the Servicio Meteorológico Nacional (SMN). These measurements were analysed and the results were compared to previous measurements performed at the same site with the radiometer of the Antarctic NILU-UV network during 2000–2008 and to data from five stations across Antarctica. In 2017/2018 the monthly-average erythemal daily doses from October to January were lower than those averaged over 2000–2008 with differences from 2.3 % to 25.5 %. In 2017/2018 the average daily erythemal dose from September to March was 1.88 kJ m−2, while in 2018/2019 it was 23 % larger (2.37 kJ m−2). Also at several other stations in Antarctica the UV radiation levels in 2017/2018 were below average. The maximum UV indices (UVI) in Marambio were 6.2 and 9.5 in 2017/2018 and 2018/2019, respectively, whereas during years 2000–2008 the maximum was 12. Cloud cover, the strength of the polar vortex and the stratospheric ozone depletion are the primary factors that influence the surface UV radiation levels in Marambio. The lower UV irradiance values in 2017/2018 are explained by the high ozone concentrations in November, February and for a large part of October. The role of cloud cover was clearly seen in December, and to a lesser extent in October and November, when cloud cover qualitatively explains changes which could not be ascribed to changes in total ozone column (TOC). In this study, the roles of aerosols and albedo are of minor influence because the variation of these factors in Marambio was small from one year to the other. The largest variations of UV irradiance occur during spring and early summer when noon solar zenith angle (SZA) is low and the stratospheric ozone concentration is at a minimum (the so-called ozone hole). In 2017/2018, coincident low total ozone column and low cloudiness near solar noon did not occur, and no extreme UV indices were measured.

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Symptoms of total ozone recovery inside the Antarctic vortex during Austral spring

10.5194/acp-2017-1157 ◽

2017 ◽

Author(s):

Andrea Pazmino ◽

Sophie Godin-Beekmann ◽

Alain Hauchecorne ◽

Chantal Claud ◽

Sergey Khaykin ◽

...

Keyword(s):

Total Ozone ◽

Ozone Hole ◽

Polar Regions ◽

Multilinear Regression ◽

Austral Spring ◽

Quasi Biennial Oscillation ◽

Total Ozone Column ◽

The Antarctic ◽

Ozone Column ◽

Mlr Model

Abstract. The long-term evolution of total ozone column inside the Antarctic polar vortex is investigated over the 1980–2016 period. Trend analyses are performed using a multilinear regression (MLR) model based on various proxies (heat flux, Quasi-Biennial Oscillation, solar flux, Antarctic Oscillation and aerosols). Annual total ozone column corresponding to the mean monthly values inside the vortex in September and during the period of maximum ozone depletion from September 15th to October 15th are used. Total ozone columns from combined SBUV, TOMS and OMI satellite datasets and the Multi-Sensor Reanalysis (MSR-2) dataset are considered in the study. Ozone trends are computed by a piecewise trend model (PWT) before and after the turnaround in 2001. In order to evaluate total ozone within the vortex, two classification methods are used, based on the potential vorticity gradient as a function of equivalent latitude. The first standard one considers this gradient at a single isentropic level (475 K or 550 K), while the second one uses a range of isentropic levels between 400 K and 600 K. The regression model includes a new proxy that represents the stability of the vortex during the studied month period. The determination coefficient (R2) between observations and modeled values increases by ~ 0.05 when this proxy is included in the MLR model. The higher R2 (0.93–0.95) and the minimum residuals are observed for the second classification method for both datasets and months periods. Trends in September are statistically significant at 2 sigma level over 2001–2016 period with values ranging between 1.85 and 2.67 DU yr−1 depending on the methods and data sets. This result confirms the recent studies of Antarctic ozone healing during that month. Trends after 2001 are 2 to 3 times lower than before the turnaround year as expected from the response to the slowly ozone-depleting substances decrease in Polar regions. Estimated trends in the 15 Sept–15 Oct period are smaller than in September. They vary from 1.15 to 1.78 DU yr−1 and are hardly significant at 2σ level. Ozone recovery is also confirmed by a steady decrease of the relative area of total ozone values lower than 150 DU within the vortex in the 15 Sept–15 Oct period since 2010. Comparison of the evolution of the ozone hole area in September and October shows a decrease in September, confirming the later formation of the ozone hole during that month.

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GUV long-term measurements of total ozone column and effective cloud transmittance at three Norwegian sites

10.5194/acp-2021-54 ◽

2021 ◽

Author(s):

Tove M. Svendby ◽

Bjørn Johnsen ◽

Arve Kylling ◽

Arne Dahlback ◽

Germar H. Bernhard ◽

...

Keyword(s):

Total Ozone ◽

Monitoring Network ◽

Ozone Hole ◽

The Arctic ◽

High Time Resolution ◽

Data Sets ◽

Total Ozone Column ◽

Ice Melt ◽

Arctic Ice ◽

Ozone Column

Abstract. Measurements of total ozone column and effective cloud transmittance have been performed since 1995 at the three Norwegian sites Oslo/Kjeller, Andøya/Tromsø and in Ny-Ålesund (Svalbard). These sites are a subset of 9 stations included in the Norwegian UV monitoring network, which uses GUV multi-filter instruments and is operated by DSA and NILU. The network includes unique data sets of high time-resolution measurements that can be used for a for broad range of atmospheric and biological exposure studies. Comparison of the 25-year records of GUV (global sky) total ozone measurements with Brewer direct sun measurements show that the GUVs provide valuable supplements to the more standardized ground-based instruments. The GUVs can fill in missing data and extend the measuring season at sites with reduced staff and/or characterized by harsh environmental conditions, such as Ny-Ålesund. Also, a harmonized GUV can easily be moved to more remote/unmanned locations and provide independent total ozone column datasets. The GUV in Ny-Ålesund captured well the Arctic ozone hole in March/April 2020, whereas the GUV in Oslo recorded a mini ozone hole in December 2019 with total ozone values below 200 DU. For all the three Norwegian stations there is a slight increase in total ozone from 1995 until today. Measurements of GUV effective cloud transmittance in Ny-Ålesund indicate that there has been a significant change in albedo during the past 25 years, most likely resulting from increased temperatures and Arctic ice melt in the area surrounding Svalbard.

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Evaluation of Total Ozone Column from Multiple Satellite Measurements in the Antarctic Using the Brewer Spectrophotometer

Remote Sensing ◽

10.3390/rs13081594 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1594

Author(s):

Songkang Kim ◽

Sang-Jong Park ◽

Hana Lee ◽

Dha Hyun Ahn ◽

Yeonjin Jung ◽

...

Keyword(s):

Satellite Data ◽

Total Ozone ◽

Spatiotemporal Pattern ◽

Satellite Measurements ◽

Austral Spring ◽

Total Ozone Column ◽

Brewer Spectrophotometer ◽

The Antarctic ◽

Ozone Column

The ground-based ozone observation instrument, Brewer spectrophotometer (Brewer), was used to evaluate the quality of the total ozone column (TOC) produced by multiple polar-orbit satellite measurements at three stations in Antarctica (King Sejong, Jang Bogo, and Zhongshan stations). While all satellite TOCs showed high correlations with Brewer TOCs (R = ~0.8 to 0.9), there are some TOC differences among satellite data in austral spring, which is mainly attributed to the bias of Atmospheric Infrared Sounder (AIRS) TOC. The quality of satellite TOCs is consistent between Level 2 and 3 data, implying that “which satellite TOC is used” can induce larger uncertainty than “which spatial resolution is used” for the investigation of the Antarctic TOC pattern. Additionally, the quality of satellite TOC is regionally different (e.g., OMI TOC is a little higher at the King Sejong station, but lower at the Zhongshan station than the Brewer TOC). Thus, it seems necessary to consider the difference of multiple satellite data for better assessing the spatiotemporal pattern of Antarctic TOC.

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Seasonal impact of biogenic VSL bromine on the evolution of mid-latitude lowermost stratospheric ozone during the 21<sup>st</sup> century

10.5194/acp-2019-1091 ◽

2020 ◽

Author(s):

Javer A. Barrera ◽

Rafael P. Fernandez ◽

Fernando Iglesias-Suarez ◽

Carlos A. Cuevas ◽

Jean-Francois Lamarque ◽

...

Keyword(s):

21St Century ◽

Total Ozone ◽

Stratospheric Ozone ◽

Polar Regions ◽

Total Ozone Column ◽

Seasonal Impact ◽

The Tropics ◽

The Impact ◽

Ozone Column ◽

Modelling Study

Abstract. Biogenic very short-lived bromine (VSLBr) represents, nowadays, ~ 25 % of the total stratospheric bromine loading. Owing to their much shorter lifetime compared to anthropogenic long-lived bromine (LLBr, e.g., halons) and chlorine (LLCl, e.g., chlorofluorocarbons) substances, the impact of VSLBr on ozone peaks at the extratropical lowermost stratosphere, a key climatic and radiative atmospheric region. Here we present a modelling study of the evolution of stratospheric ozone and its chemical losses in extra-polar regions during the 21st century, under two different scenarios: considering and neglecting the additional stratospheric injection of 5 ppt biogenic VSLBr naturally released from the ocean. Our analysis shows that the inclusion of VSLBr result in a realistic stratospheric bromine loading and improves the quantitative 1980–2015 model-satellite agreement of total ozone column (TOC) in the mid-latitudes. We show that the overall ozone response to VSLBr within the mid-latitudes follows the stratospheric abundances evolution of long-lived inorganic chlorine and bromine throughout the 21st century. Additional ozone losses due to VSLBr are maximised during the present-day period (1990–2010), with TOC differences of −8 DU (−3 %) and −5.5 DU (−2 %) for the southern (SH-ML) and northern (NH-ML) mid-latitudes, respectively. Moreover, the projected TOC differences at the end of the 21st century are at least half of the values found for the present-day period. In the tropics, a small (

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Lagrangian analysis of the northern polar vortex split in April 2020 during development of the Arctic ozone hole

10.5194/egusphere-egu21-13597 ◽

2021 ◽

Author(s):

Jezabel Curbelo ◽

Gang Chen ◽

Carlos R. Mechoso

Keyword(s):

Wave Train ◽

Stratospheric Ozone ◽

Polar Vortex ◽

Early Spring ◽

Ozone Hole ◽

The Arctic ◽

Late Winter ◽

Lagrangian Analysis ◽

The North ◽

Vortex Split

<div>The evolution of the Northern Hemisphere stratosphere during late winter and early spring of 2020 was punctuated by outstanding events both in dynamics and tracer evolution. It provides an ideal case for study of the Lagrangian properties of the evolving flow and its connections with the troposphere. The events ranged from an episode of polar warming at upper levels in March, a polar vortex split into two cyclonic vortices at middle and lower levels in April, and a remarkably deep and persistent mass of ozone poor air within the westerly circulation throughout the period. The latter feature was particularly remarkable during 2020, which showed the lowest values of stratospheric ozone on record.</div><div>&#160;</div><div>We focus on the vortex split in April 2020 and we examine this split at middle as well as lower stratospheric levels, and the interactions that occurred between the resulting two vortices which determined the distribution of ozone among them. We also examine the connections among stratospheric and tropospheric events during the period.</div><div>&#160;</div><div>Our approach for analysis will be based on the application of Lagrangian tools to the flow field, based on following air parcels trajectories, examining barriers to the flow, and the activity and propagation of planetary waves. Our findings confirm the key role for the split played by a flow configuration with a polar hyperbolic trajectory and associated manifolds. A trajectory analysis illustrates the transport of ozone between the vortices during the split. We argue that these stratospheric events were linked to strong synoptic scale disturbances in the troposphere forming a wave train from the north Pacific to North America and Eurasia.</div><div><strong>&#160;</strong></div><div><strong>Reference:</strong><strong> </strong>J. Curbelo, G. Chen,&#160; C. R. Mechoso. Multi-level analysis of the northern polar vortex split in April 2020 during development of the Arctic ozone hole. Earth and Space Science Open Archive. doi: 10.1002/essoar.10505516.1</div><div>&#160;</div><div><strong>Acknowledgements:</strong> NSF Grant AGS-1832842, RYC2018-025169 and EIN2019-103087.</div>

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The influence of polar vortex ozone depletion on NH mid-latitude ozone trends in spring

Atmospheric Chemistry and Physics ◽

10.5194/acp-6-2837-2006 ◽

2006 ◽

Vol 6 (10) ◽

pp. 2837-2845 ◽

Cited By ~ 10

Author(s):

S. B. Andersen ◽

B. M. Knudsen

Keyword(s):

Lower Limit ◽

Ozone Depletion ◽

Total Ozone ◽

Polar Vortex ◽

Major Fraction ◽

Total Ozone Column ◽

Trajectory Calculations ◽

Ozone Trends ◽

Decadal Variations ◽

Ozone Column

Abstract. Reverse domain-filling trajectory calculations have been performed for the years 1993, 1995, 1996, 1997, and 2000 to calculate the spreading of ozone depleted air from the polar vortex to midlatitudes in spring. We find that for these years with massive Arctic ozone depletion the zonal mean total ozone column at midlatitudes is reduced with between 7 and 12 DU in the April-May period. The polar vortex and remnants have preferred locations which leads to longitudinal differences in the midlatitude ozone trends. Together with decadal variations in circulation the dilution of ozone depleted air may explain the major fraction of longitudinal differences in midlatitude ozone trends. For the period 1979–1997 the dilution may explain 50% of the longitudinal differences in ozone trends and for the period 1979–2002 it may explain 45%. The dilution also has a significant impact on the zonal mean ozone trends in the April-May period. Although uncertainties are large due to uncertainties in the ozone depletion values and neglect of ozone depletion in other years than 1993, 1995, 1996, 1997, and 2000 we have tried to calculate the size of this effect. We estimate that dilution may explain 29% of the trend in the period 1979–1997 and 33% of the trend in the period 1979–2002 as a lower limit.

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