Unprecedented Ozone Depletion in the Arctic Stratosphere during Winter–Spring of 2020

The Arctic winter of 2019-2020 was characterized by an unusually persistent polar vortex and temperatures in the lower stratosphere that were consistently below the threshold for the formation of polar stratospheric clouds (PSCs). These conditions led to ozone loss that is comparable to the Antarctic ozone hole. Ground-based measurements from a suite of instruments at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05&#176;N, 86.42&#176;W) were used to investigate chemical ozone depletion. The vortex was located above Eureka longer than in any previous year in the 20-year dataset and lidar measurements provided evidence of polar stratospheric clouds (PSCs) above Eureka. Additionally, UV-visible zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements showed record ozone loss in the 20-year dataset, evidence of denitrification along with the slowest increase of NO2 during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO2 (chlorine reservoir species) from a Fourier transform infrared (FTIR) spectrometer showed unusually low columns that were comparable to 2011, the previous year with significant chemical ozone depletion. Record low values of HNO3 in the FTIR dataset are in accordance with the evidence of PSCs and a denitrified atmosphere. Estimates of chemical ozone loss were derived using passive ozone from the SLIMCAT offline chemical transport model to account for dynamical contributions to the stratospheric ozone budget.

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Active molecular iodine photochemistry in the Arctic

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1702803114 ◽

2017 ◽

Vol 114 (38) ◽

pp. 10053-10058 ◽

Cited By ~ 28

Author(s):

Angela R. W. Raso ◽

Kyle D. Custard ◽

Nathaniel W. May ◽

David Tanner ◽

Matt K. Newburn ◽

...

Keyword(s):

Ozone Depletion ◽

Radiative Forcing ◽

Elemental Mercury ◽

Molecular Iodine ◽

Atmospheric Composition ◽

The Arctic ◽

Ionization Mass ◽

Gaseous Elemental Mercury ◽

Cloud Properties ◽

Iodine Chemistry

During springtime, the Arctic atmospheric boundary layer undergoes frequent rapid depletions in ozone and gaseous elemental mercury due to reactions with halogen atoms, influencing atmospheric composition and pollutant fate. Although bromine chemistry has been shown to initiate ozone depletion events, and it has long been hypothesized that iodine chemistry may contribute, no previous measurements of molecular iodine (I2) have been reported in the Arctic. Iodine chemistry also contributes to atmospheric new particle formation and therefore cloud properties and radiative forcing. Here we present Arctic atmospheric I2and snowpack iodide (I−) measurements, which were conducted near Utqiaġvik, AK, in February 2014. Using chemical ionization mass spectrometry, I2was observed in the atmosphere at mole ratios of 0.3–1.0 ppt, and in the snowpack interstitial air at mole ratios up to 22 ppt under natural sunlit conditions and up to 35 ppt when the snowpack surface was artificially irradiated, suggesting a photochemical production mechanism. Further, snow meltwater I−measurements showed enrichments of up to ∼1,900 times above the seawater ratio of I−/Na+, consistent with iodine activation and recycling. Modeling shows that observed I2levels are able to significantly increase ozone depletion rates, while also producing iodine monoxide (IO) at levels recently observed in the Arctic. These results emphasize the significance of iodine chemistry and the role of snowpack photochemistry in Arctic atmospheric composition, and imply that I2is likely a dominant source of iodine atoms in the Arctic.

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The effect of small-scale inhomogeneities on ozone depletion in the Arctic

Nature ◽

10.1038/384444a0 ◽

1996 ◽

Vol 384 (6608) ◽

pp. 444-447 ◽

Cited By ~ 95

Author(s):

S. Edouard ◽

B. Legras ◽

F. Lefèvre ◽

R. Eymard

Keyword(s):

Ozone Depletion ◽

The Arctic ◽

Small Scale

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Ozone in the Boundary Layer air over the Arctic Ocean – measurements during the TARA expedition

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-8561-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 8561-8586

Author(s):

J. W. Bottenheim ◽

S. Netcheva ◽

S. Morin ◽

S. V. Nghiem

Keyword(s):

Boundary Layer ◽

Arctic Ocean ◽

Ozone Depletion ◽

Surface Ozone ◽

The Arctic ◽

Total Absence ◽

Trajectory Calculations ◽

The Arctic Ocean ◽

Ocean Measurements ◽

Siberian Coast

Abstract. A full year of measurements of surface ozone over the Arctic Ocean far removed from land is presented (81° N – 88° N latitude). The data were obtained during the drift of the French schooner TARA between September 2006 and January 2008, while frozen in the Arctic Ocean. The data confirm that long periods of virtually total absence of ozone occur in the spring (mid March to mid June) after Polar sunrise. At other times of the year ozone concentrations are comparable to other oceanic observations with winter mole fractions of ca. 30–40 nmol mol−1 and summer minima of ca. 20 nmol mol−1. Contrary to earlier observations from ozone sonde data obtained at Arctic coastal observatories, the ambient temperature was well above −20°C during most ODEs (ozone depletion episodes). Backwards trajectory calculations suggest that during these ODEs the air had previously been in contact with the frozen ocean surface for several days and originated largely from the Siberian coast where several large open flaw leads developed in the spring of 2007.

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Observation of HClO3 and HClO4 in the Arctic atmosphere

10.5194/egusphere-egu2020-16908 ◽

2020 ◽

Author(s):

Yee Jun Tham ◽

Nina Sarnela ◽

Carlos A. Cuevas ◽

Iyer Siddharth ◽

Lisa Beck ◽

...

Keyword(s):

Gas Phase ◽

Ozone Depletion ◽

Surface Ozone ◽

Negative Ion ◽

The Arctic ◽

Research Station ◽

Visible Absorption ◽

Data Set ◽

Near Surface ◽

Arctic Atmosphere

Atmospheric halogens chemistry like the catalytic reaction of bromine and chlorine radicals with ozone (O3) has been known to cause the springtime surface-ozone destruction in the polar region. Although the initial atmospheric reactions of chlorine with ozone are well understood, the &#64257;nal oxidation steps leading to the formation of chlorate (ClO3-) and perchlorate (ClO4-) remain unclear due to the lack of direct evidence of their presence and fate in the atmosphere. In this study, we present the first high-resolution ambient data set of gas-phase HClO3 (chloric acid) and HClO4 (perchlorate acid) obtained from the field measurement at the Villum Research Station, Station Nord, in high arctic North Greenland (81&#176;36&#8217; N, 16&#176;40&#8217; W) during the spring of 2015. A state-of-the-art chemical ionization atmospheric pressure interface time-of-flight mass spectrometer (CI-APi-TOF) was used in negative ion mode with nitrate ion as the reagent ion to detect the gas-phase HClO3 and HClO4. We measured significant level of HClO3 and HClO4 only during the springtime ozone depletion events in the Greenland, with concentration up to 9x105 molecule cm-3. Air mass trajectory analysis shows that the air during the ozone depletion event was confined to near-surface, indicating that the O3 and surface of sea-ice/snowpack may play important roles in the formation of HClO3 and HClO4. We used high-level quantum-chemical methods to calculate the ultraviolet-visible absorption spectra and cross-section of HClO3 and HClO4 in the gas-phase to assess their fates in the atmosphere. Overall, our results reveal the presence of HClO3 and HClO4 during ozone depletion events, which could affect the chlorine chemistry in the Arctic atmosphere.

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Numerical analysis of the chemical kinetic mechanisms of ozone depletion and halogen release in the polar troposphere

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-24171-2013 ◽

2013 ◽

Vol 13 (9) ◽

pp. 24171-24222 ◽

Cited By ~ 1

Author(s):

L. Cao ◽

H. Sihler ◽

U. Platt ◽

E. Gutheil

Keyword(s):

Boundary Layer ◽

Surface Area ◽

Ozone Depletion ◽

Reaction Rates ◽

The Arctic ◽

Strong Impact ◽

Reactive Surface ◽

A Value ◽

Halogen Species

Abstract. In recent years, the role of halogen species (e.g. Br, Cl) in the troposphere of polar regions is investigated after the discovery of their importance for boundary layer ozone destruction in the polar spring. Halogen species take part in an auto-catalytic chemical cycle including key self reactions. In this study, several chemical reaction schemes are investigated, and the importance of specific reactions and their rate constants is identified by a sensitivity analysis. A category of heterogeneous reactions related to HOBr activate halogen ions from sea salt aerosols, fresh sea ice or snow pack, driving the "bromine explosion". In the Arctic, a small amount of NOx may exist, which comes from nitrate contained in the snow, and this NOx may have a strong impact on ozone depletion. The heterogeneous reaction rates are parameterized by considering the aerodynamic resistance, a reactive surface ratio, β, i.e. ratio of reactive surface area to total ground surface area, and the boundary layer height, Lmix. It is found that for β = 1, the ozone depletion process starts after five days and lasts for 40 h for Lmix = 200 m. Ozone depletion duration becomes independent of the height of the boundary layer for about β≥20, and it approaches a value of two days for β=100. The role of nitrogen and chlorine containing species on the ozone depletion rate is studied. The calculation of the time integrated bromine and chlorine atom concentrations suggests a value in the order of 103 for the [Br] / [Cl] ratio, which reveals that atomic chlorine radicals have minor direct influence on the ozone depletion. The NOx concentrations are influenced by different chemical cycles over different time periods. During ozone depletion, the reaction cycle involving the BrONO2 hydrolysis is dominant. A critical value of 0.002 of the uptake coefficient of the BrONO2 hydrolysis reaction at the aerosol and saline surfaces is identified, beyond which the existence of NOx species accelerate the ozone depletion event – for lower values, deceleration occurs.

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The chemistry influencing ODEs in the Polar Boundary Layer in spring: a model study

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-7391-2008 ◽

2008 ◽

Vol 8 (2) ◽

pp. 7391-7453 ◽

Cited By ~ 1

Author(s):

M. Piot ◽

R. von Glasow

Keyword(s):

Boundary Layer ◽

Ozone Depletion ◽

Chemical Species ◽

Field Measurements ◽

The Arctic ◽

Direct Reaction ◽

Mixing Ratios ◽

Model Study ◽

Sensitivity Studies ◽

Chemical Conditions

Abstract. Near-total depletions of ozone have been observed in the Arctic spring since the mid 1980s. The autocatalytic cycles involving reactive halogens are now recognized to be of main importance for Ozone Depletion Events (ODEs) in the Polar Boundary Layer (PBL). We present sensitivity studies using the model MISTRA in the box-model mode on the influence of chemical species on these ozone depletion processes. In order to test the sensitivity of the chemistry under polar conditions, we compared base runs undergoing fluxes of either Br2, BrCl, or Cl2 to induce ozone depletions, with similar runs including a modification of the chemical conditions. The role of HCHO, H2O2, DMS, Cl2, C2H4, C2H6, HONO, NO2, and RONO2 was investigated. Cases with elevated mixing ratios of HCHO, H2O2, DMS, Cl2, and HONO induced a shift in bromine speciation from Br/BrO to HOBr/HBr, while high mixing ratios of C2H6 induced a shift from HOBr/HBr to Br/BrO. Cases with elevated mixing ratios of HONO, NO2, and RONO2 induced a shift to BrNO2/BrONO2. The shifts from Br/BrO to HOBr/HBr accelerated the aerosol debromination, but also increased the total amount of deposited bromine at the surface (mainly via increased deposition of HOBr). These shifts to HOBr/HBr also hindered the BrO self-reaction. In these cases, the ozone depletion was slowed down, where increases in H2O2 and HONO had the greatest effect. The tests with increased mixing ratios of C2H4 highlighted the decrease in HOx which reduced the production of HOBr from bromine radicals. In addition, the direct reaction of C2H4 with bromine atoms led to less available reactive bromine. The aerosol debromination was therefore strongly reduced. Ozone levels were highly affected by the chemistry of C2H4. Cl2-induced ozone depletions were found unrealistic compared to field measurements due to the rapid production of CH3O2, HOx, and ROOH which rapidly convert reactive chlorine to HCl in a "chlorine counter-cycle". This counter-cycle efficiently reduces the concentration of reactive halogens in the boundary layer. Depending on the relative bromine and chlorine mixing ratios, the production of CH3O2, HOx, and ROOH from the counter-cycle can significantly affect the bromine chemistry. Therefore, the presence of both bromine and chlorine in the air may unexpectedly lead to a slow down in ozone destruction. For all NOy species studied (HONO, NO2, RONO2) the chemistry is characterized by an increased bromine deposition on snow reducing the amount of reactive bromine in the air. Ozone is less depleted under conditions of high mixing ratios of NOx. The production of HNO3 led to the acid displacement of HCl, and the release of chlorine out of salt aerosols (Cl2 or BrCl) increased.

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A model study of tropospheric impacts of the Arctic ozone depletion 2011

Journal of Geophysical Research Atmospheres ◽

10.1002/2013jd021350 ◽

2014 ◽

Vol 119 (13) ◽

pp. 7999-8014 ◽

Cited By ~ 23

Author(s):

Alexey Yu. Karpechko ◽

Judith Perlwitz ◽

Elisa Manzini

Keyword(s):

Ozone Depletion ◽

The Arctic ◽

Model Study

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The Influence of Ozone Feedbacks on Surface Climate following Spring Arctic Ozone Depletion

10.5194/egusphere-egu21-12668 ◽

2021 ◽

Author(s):

Marina Friedel ◽

Gabriel Chiodo ◽

Andrea Stenke ◽

Daniela Domeisen ◽

Stefan Muthers ◽

...

Keyword(s):

Ozone Depletion ◽

Arctic Oscillation ◽

Stratospheric Ozone ◽

The Arctic ◽

Model Simulations ◽

Temperature Anomalies ◽

Surface Climate ◽

Anomalous Surface ◽

Surface Weather ◽

Surface Patterns

Links between springtime Arctic stratospheric ozone anomalies and anomalous surface weather in the Northern Hemisphere have been found recently. Stratospheric ozone thus provides valuable information which may help to improve seasonal predictability. However, the extent and causality of the ozone-surface climate coupling remain unclear and many state-of-the-art forecast models lack any representation of ozone feedbacks on planetary circulation.We investigate the importance of the ozone-surface climate coupling with two Chemistry Climate Models, contrasting simulations with fully interactive ozone against prescribed zonally averaged climatological ozone under fixed present-day boundary conditions. We focus on springtime Arctic ozone minima and compare subsequent surface patterns in runs with and without interactive ozone, thus rendering a detailed and physically-based quantification of the stratospheric ozone impact on surface climate possible. &#160;All model simulations show a connection between Arctic ozone minima and a positive phase of the Arctic Oscillation in the month after the depletion in spring. Runs with interactive ozone chemistry show an amplified surface response and a 40% stronger Arctic Oscillation index after ozone depletion. This amplified Arctic Oscillation goes along with enhanced positive surface temperature anomalies over Eurasia. Moreover, composite surface patterns after spring ozone minima in model simulations with interactive ozone show a better agreement with composites in reanalysis data compared to runs with prescribed ozone.Mechanisms whereby stratospheric ozone affects both the stratospheric and tropospheric circulation are explored. These include the reduction of short-wave heating over the pole due to ozone loss, thus amplifying stratospheric temperature anomalies and allowing for an intensification of the polar vortex with subsequent impacts on wave propagation and the stratospheric meridional circulation. This suggests that ozone is not only passively responding to stratospheric dynamics, but actively feeds back into the circulation. Following these results, stratospheric ozone anomalies actively contribute to anomalous surface weather in spring, emphasizing the potential importance of interactive ozone chemistry for seasonal predictions.

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Cyclone-induced surface ozone and HDO depletion in the Arctic

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-14955-2017 ◽

2017 ◽

Vol 17 (24) ◽

pp. 14955-14974 ◽

Cited By ~ 6

Author(s):

Xiaoyi Zhao ◽

Dan Weaver ◽

Kristof Bognar ◽

Gloria Manney ◽

Luis Millán ◽

...

Keyword(s):

Ozone Depletion ◽

Deuterium Oxide ◽

Surface Ozone ◽

Weddell Sea ◽

Cloud Layer ◽

The Arctic ◽

Blowing Snow ◽

Near Surface ◽

Air Masses ◽

Ice Cloud

Abstract. Ground-based, satellite, and reanalysis datasets were used to identify two similar cyclone-induced surface ozone depletion events at Eureka, Canada (80.1° N, 86.4° W), in March 2007 and April 2011. These two events were coincident with observations of hydrogen deuterium oxide (HDO) depletion, indicating that condensation and sublimation occurred during the transport of the ozone-depleted air masses. Ice clouds (vapour and crystals) and aerosols were detected by lidar and radar when the ozone- and HDO-depleted air masses arrived over Eureka. For the 2007 event, an ice cloud layer was coincident with an aloft ozone depletion layer at 870 m altitude on 2–3 March, indicating this ice cloud layer contained bromine-enriched blowing-snow particles. Over the following 3 days, a shallow surface ozone depletion event (ODE) was observed at Eureka after the precipitation of bromine-enriched particles onto the local snowpack. A chemistry–climate model (UKCA) and a chemical transport model (pTOMCAT) were used to simulate the surface ozone depletion events. Incorporating the latest surface snow salinity data obtained for the Weddell Sea into the models resulted in improved agreement between the modelled and measured BrO concentrations above Eureka. MERRA-2 global reanalysis data and the FLEXPART particle dispersion model were used to study the link between the ozone and HDO depletion. In general, the modelled ozone and BrO showed good agreement with the ground-based observations; however, the modelled BrO and ozone in the near-surface layer are quite sensitive to the snow salinity. HDO depletion observed during these two blowing-snow ODEs was found to be weaker than pure Rayleigh fractionation. This work provides evidence of a blowing-snow sublimation process, which is a key step in producing bromine-enriched sea-salt aerosol.

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