scholarly journals Differentiation of coarse-mode anthropogenic, marine and dust particles in the High Arctic islands of Svalbard

2021 ◽  
Vol 21 (14) ◽  
pp. 11317-11335
Author(s):  
Congbo Song ◽  
Manuel Dall'Osto ◽  
Angelo Lupi ◽  
Mauro Mazzola ◽  
Rita Traversi ◽  
...  
Keyword(s):  
The Arctic ◽  
Dust Particles ◽  
Sea Spray ◽  
Polar Regions ◽  
Blowing Snow ◽  
Long Distance ◽  
Svalbard Archipelago ◽  
Coarse Mode ◽  
Arctic Haze ◽  
Natural Aerosol

Abstract. Understanding aerosol–cloud–climate interactions in the Arctic is key to predicting the climate in this rapidly changing region. Whilst many studies have focused on submicrometer aerosol (diameter less than 1 µm), relatively little is known about the supermicrometer aerosol (diameter above 1 µm). Here, we present a cluster analysis of multiyear (2015–2019) aerodynamic volume size distributions, with diameter ranging from 0.5 to 20 µm, measured continuously at the Gruvebadet Observatory in the Svalbard archipelago. Together with aerosol chemical composition data from several online and offline measurements, we apportioned the occurrence of the coarse-mode aerosols during the study period (mainly from March to October) to anthropogenic (two sources, 27 %) and natural (three sources, 73 %) origins. Specifically, two clusters are related to Arctic haze with high levels of black carbon, sulfate and accumulation mode (0.1–1 µm) aerosol. The first cluster (9 %) is attributed to ammonium sulfate-rich Arctic haze particles, whereas the second one (18 %) is attributed to larger-mode aerosol mixed with sea salt. The three natural aerosol clusters were open-ocean sea spray aerosol (34 %), mineral dust (7 %) and an unidentified source of sea spray-related aerosol (32 %). The results suggest that sea-spray-related aerosol in polar regions may be more complex than previously thought due to short- and long-distance origins and mixtures with Arctic haze, biogenic and likely blowing snow aerosols. Studying supermicrometer natural aerosol in the Arctic is imperative for understanding the impacts of changing natural processes on Arctic aerosol.

scholarly journals Differentiation of coarse-mode anthropogenic, marine and dust particles in the high Arctic Islands of Svalbard

2021 ◽  
Author(s):  
Congbo Song ◽  
Manuel Dall’Osto ◽  
Angelo Lupi ◽  
Mauro Mazzola ◽  
Rita Traversi ◽  
...  
Keyword(s):  
High Arctic ◽  
The Arctic ◽  
Dust Particles ◽  
Sea Spray ◽  
Polar Regions ◽  
Long Distance ◽  
Svalbard Archipelago ◽  
Coarse Mode ◽  
Arctic Haze ◽  
Natural Aerosol

Abstract. Understanding aerosol-cloud-climate interactions in the Arctic is key to predict the climate in this rapidly changing region. Whilst many studies have focused on submicron aerosol (diameter less than 1 μm), relatively little is known about the climate relevance of supermicron aerosol (diameter above 1 μm). Here, we present a cluster analysis of multiyear (2015–2019) aerodynamic volume size distributions with diameter ranging from 0.5 to 20 μm measured continuously at the Gruvebadet Observatory in the Svalbard archipelago. Together with aerosol chemical composition data from several online and offline measurements, we apportioned the occurrence of the coarse-mode aerosols to anthropogenic (two sources, 27 %) and natural (three sources, 73 %) origins. Specifically, two clusters are related to Arctic haze with high levels of black carbon, sulfate and accumulation mode (0.1–1 μm) aerosol. The first cluster (9 %) is attributed to ammonium sulfate-rich Arctic haze particles, whereas the second one (18 %) to larger-mode aerosol mixed with sea salt. The three natural aerosol clusters were: open ocean sea spray aerosol (34 %), mineral dust (7 %), and an unidentified source of sea spray-related aerosol (32 %). The results suggest that sea spray-related aerosol in polar regions may be more complex than previously thought due to short/long-distance origins and mixtures with Arctic haze, biogenic and likely snow-blowing aerosols. Studying supermicron natural aerosol in the Arctic is imperative for understanding the impacts of changing natural processes on Arctic aerosol.

Measurements of bromine monoxide over four halogen activation seasons in the Canadian high Arctic

2020 ◽  
Author(s):  
Kristof Bognar ◽  
Xiaoyi Zhao ◽  
Kimberly Strong ◽  
Rachel Y.-W. Chang ◽  
Udo Frieß ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Vertical Mixing ◽  
Temperature Inversion ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Blowing Snow ◽  
Atmospheric Conditions ◽  
Coarse Mode ◽  
Arctic Haze

<p><span>Bromine explosions and corresponding ozone depletion events (ODEs) are common in the Arctic spring. The snowpack on sea ice and sea salt aerosols (SSA) are both thought to release bromine, but the relative contribution of each source is not yet known. Furthermore, the role of atmospheric conditions is not fully understood. Long-term measurements of bromine monoxide (BrO) provide useful insight into the underlying processes of bromine activation. Here we present a four-year dataset (2016-2019) of springtime BrO partial columns retrieved from Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements in Eureka, Canada (80.1° N, 86.4° W). Due to the altitude of the measurement site (610 m), the measurements often represent BrO above the shallow boundary layer, and the strength of the temperature inversion has limited impact on the BrO partial columns. When the boundary layer is deep, however, the effects of the enhanced vertical mixing manifest as an increase in the minimum BrO values (and reduced ODE frequency) for wind speeds of ~8 m/s or greater. We find that BrO events show two modes differentiated by local wind direction and air mass history. Longer time spent in first-year sea ice areas corresponds to increased BrO for one of these modes only. We argue that snow on multi-year ice (salted and acidified by Arctic haze) might also contribute to bromine release. The MAX-DOAS measurements show that high aerosol optical depth is required to maintain lofted BrO. In situ measurements indicate that accumulation mode aerosols (mostly Arctic haze) have no direct correlation with BrO. The presence of coarse mode aerosols, however, is a necessary and sufficient condition for observing enhanced BrO at Eureka. The measurements of coarse mode aerosols are consistent with SSA generated from blowing snow. The good correlation between BrO and coarse mode aerosols (R<sup>2</sup> up to 0.57) supports the view that SSA is a direct source of bromine to the polar troposphere.</span></p>

Pan-Arctic surface ozone seasonality modified by sea-ice-sourced bromine: modelling vs measurements

2021 ◽  
Author(s):  
Xin Yang ◽  
Anne-M Blechschmidt2 ◽  
Kristof Bognar ◽  
Audra McClure–Begley ◽  
Sara Morris ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Surface Ozone ◽  
Open Ocean ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Spray ◽  
Research Station ◽  
Blowing Snow ◽  
Model Control

<p>Within the framework of the International Arctic Systems for Observing the Atmosphere (IASOA), we report a modelling-based study on surface ozone across the Arctic. We use surface ozone from six sites: Summit (Greenland), Pallas (Finland), Barrow (USA), Alert (Canada), Tiksi (Russia), and Villum Research Station (VRS) at Station Nord (North Greenland, Danish Realm), and ozonesonde data from three Canadian sites: Resolute, Eureka, and Alert. Two global chemistry models: a global chemistry transport model (p-TOMCAT) and a global chemistry climate model (UKCA), are used for model-data comparisons. Remotely sensed data of BrO from the GOME-2 satellite instrument at Eureka, Canada are used for model validation.</p><p>The observed climatology data show that spring surface ozone at coastal Arctic is heavily depleted, making ozone seasonality at Arctic coastal sites distinctly different from that at inland sites. Model simulations show that surface ozone can be greatly reduced by bromine chemistry. In April, bromine chemistry can cause a net ozone loss (monthly mean) of 10-20 ppbv, with almost half attributable to open-ocean-sourced bromine and the rest to sea-ice-sourced bromine. However, the open-ocean-sourced bromine, via sea spray bromide depletion, cannot by itself produce ozone depletion events (ODEs) (defined as ozone volume mixing ratios VMRs < 10 ppbv). In contrast, sea-ice-sourced bromine, via sea salt aerosol (SSA) production from blowing snow, can produce ODEs even without bromine from sea spray, highlighting the importance of sea ice surface in polar boundary layer chemistry.</p><p>Modelled total inorganic bromine (Br<sub>Y</sub>) over the Arctic sea ice  is sensitive to model configuration, e.g., under the same bromine loading, Br<sub>Y</sub> in the Arctic spring boundary layer in the p-TOMCAT control run (i.e., with all bromine emissions) can be 2 times that in the UKCA control run. Despite the model differences, both model control runs can successfully reproduce large bromine explosion events (BEEs) and ODEs in polar spring. Model-integrated tropospheric column BrO generally matches GOME-2 tropospheric columns within ~50% in UKCA and a factor of 2 in p-TOMCAT. The success of the models in reproducing both ODEs and BEEs in the Arctic indicates that the relevant parameterizations implemented in the models work reasonably well, which supports the proposed mechanism of SSA production and bromide release on sea ice. Given that sea ice is a large source of SSA and halogens, changes in sea ice type and extent in a warming climate will influence Arctic boundary layer chemistry, including the oxidation of atmospheric elemental mercury. Note that this work dose not necessary rule out other possibilities that may act as a source of reactive bromine from sea ice zone.</p>

Bifidochaetus, a new Arctic genus of freshwater Chaetonotida (Gastrotricha) from Spitsbergen revealed by an integrative taxonomic approach

2016 ◽  
Vol 30 (4) ◽  
pp. 398 ◽  
Author(s):  
Małgorzata Kolicka ◽  
Miroslawa Dabert ◽  
Jacek Dabert ◽  
Tobias Kånneby ◽  
Jacek Kisielewski
Keyword(s):  
Sequence Data ◽  
Sister Group ◽  
New Combination ◽  
The Arctic ◽  
Polar Regions ◽  
28S Rrna ◽  
Svalbard Archipelago ◽  
Terrestrial Invertebrates ◽  
Intestine Length ◽  
Taxonomic Research

Gastrotricha is a cosmopolitan phylum of aquatic and semi-terrestrial invertebrates that comprises ~820 described species. To date, freshwater gastrotrichs have not been the subject of faunistic or taxonomic research in the polar regions. In this paper, we present the first species-level description of a freshwater gastrotrich from the Arctic (Svalbard Archipelago). Evidence from morphology, morphometry and molecular analyses reveals that the species represents a new genus in Chaetonotidae: Bifidochaetus arcticus, gen. et sp. nov. Taking into consideration many morphological similarities to Chaetonotus (Primochaetus) veronicae Kånneby, 2013 we propose to include C. (P.) veronicae in the newly established genus under the new combination Bifidochaetus veronicae (Kånneby, 2013), comb. nov. In the phylogenetic analysis based on nuclear 18S rRNA, 28S rRNA and mitochondrial cytochrome c oxidase subunit I sequence data, B. arcticus, gen. et sp. nov. is nested within the family Chaetonotidae, as the sister group to the genus Lepidochaetus Kisielewski, 1991. In this paper we also present new taxonomic characters useful for gastrotrich taxonomy: the pharynx-to-intestine length ratio (I) and the spine bifurcation ratio (B).

scholarly journals Pollutants present in different components of the Svalbard archipelago environment / Zanieczyszczenia obecne w różnych komponentach środowiska archipelagu Svalbard

2012 ◽  
Vol 19 (4) ◽  
pp. 571-584 ◽  
Author(s):  
Marek Ruman ◽  
Katarzyna Kozak ◽  
Sara Lehmann ◽  
Krystyna Kozioł ◽  
Żaneta Polkowska
Keyword(s):  
Measurement Data ◽  
Geographic Location ◽  
Analytical Techniques ◽  
The Arctic ◽  
Polar Regions ◽  
Negative Effects ◽  
Svalbard Archipelago ◽  
Arctic Ecosystem ◽  
Arctic Regions ◽  
Area Of Interest

Abstract During last years an interest in the processes of transport and fate of pollutants to the polar regions located distantly from industrial centers, has significantly increased. The current analytical techniques enabling conducting studies prove that the Arctic regions (in the past considered as a pollution free area) have become an area of highly intensive anthropopresion. Svalbard archipelago stands out from the other polar regions due to its specific environmental conditions and geographic location, which results in becoming a reservoir of contamination in this area. Systematic environmental monitoring of arctic regions is extremely important due to an unique opportunity of observing a direct impact of pollution on the ongoing processes in the area of interest. In this way measurement data obtained are a valuable source of information, not only on changes occurring in the Arctic ecosystem, but also on estimated global impact of certain xenobiotics present in the environment. Furthermore, qualitative and quantitative studies on particular chemicals deposited in different regions of the Arctic ecosystem may constitute the basis for undertaking actions aimed at preventing negative effects caused by these pollutants.

scholarly journals Pan-Arctic seasonal cycles and long-term trends of aerosol properties from ten observatories

2021 ◽  
Author(s):  
Julia Schmale ◽  
Sangeeta Sharma ◽  
Stefano Decesari ◽  
Jakob Pernov ◽  
Andreas Massling ◽  
...  
Keyword(s):  
Black Carbon ◽  
Methanesulfonic Acid ◽  
The Arctic ◽  
Anthropogenic Emissions ◽  
Natural Sources ◽  
Arctic Haze ◽  
Long Term Trends ◽  
Aerosol Properties ◽  
Natural Aerosol

Abstract. Even though the Arctic is remote, aerosol properties observed there are strongly influenced by anthropogenic emissions from outside the Arctic. This is particularly true for the so-called Arctic haze season (January through April). In summer (June through September), when atmospheric transport patterns change, and precipitation is more frequent, local Arctic, i.e. natural sources of aerosols and precursors, play an important role. Over the last decades, significant reductions in anthropogenic emissions have taken place. At the same time a large body of literature shows evidence that the Arctic is undergoing fundamental environmental changes due to climate forcing, leading to enhanced emissions by natural processes that may impact aerosol properties. In this study, we analyze nine aerosol chemical species and four particle optical properties from ten Arctic observatories (Alert, Gruvebadet, Kevo, Pallas, Summit, Thule, Tiksi, Barrow, Villum, Zeppelin) to understand changes in anthropogenic and natural aerosol contributions. Variables include equivalent black carbon, particulate sulfate, nitrate, ammonium, methanesulfonic acid, sodium, iron, calcium and potassium, as well as scattering and absorption coefficients, single scattering albedo and scattering Ångström exponent. First, annual cycles are investigated, which despite anthropogenic emission reductions still show the Arctic haze phenomenon. Second, long-term trends are studied using the Mann-Kendall Theil-Sen slope method. We find in total 28 significant trends over full station records, i.e. spanning more than a decade, compared to 17 significant decadal trends. The majority of significantly declining trends is from anthropogenic tracers and occurred during the haze period, driven by emission changes between 1990 and 2000. For the summer period, no uniform picture of trends has emerged. Twenty-one percent of trends, i.e. eleven out of 57, are significant, and of those five are positive and six are negative. Negative trends include not only anthropogenic tracers such as equivalent black carbon at Kevo, but also natural indicators such as methanesulfonic acid and non-sea salt calcium at Alert. Positive trends are observed for sulfate at Zeppelin and Gruvebadet. No clear evidence of a significant change in the natural aerosol contribution can be observed yet. However, testing the sensitivity of the Mann-Kendall Theil-Sen method, we find that monotonic changes of around 5 % per year in an aerosol property are needed to detect a significant trend within one decade. This highlights that long-term efforts well beyond a decade are needed to capture smaller changes. It is particularly important to understand the ongoing natural changes in the Arctic, where interannual variability can be high, such as with forest fire emissions and their influence on the aerosol population. To investigate the climate-change induced influence on the aerosol population and the resulting climate feedback, long-term observations of tracers more specific to natural sources are needed, as well as of particle microphysical properties such as size distributions, which can be used to identify changes in particle populations which are not well captured by mass-oriented methods such as bulk chemical composition.

scholarly journals Wintertime enhancements of sea salt aerosol in polar regions consistent with a sea ice source from blowing snow

2017 ◽  
Vol 17 (5) ◽  
pp. 3699-3712 ◽  
Author(s):  
Jiayue Huang ◽  
Lyatt Jaeglé
Keyword(s):  
Sea Ice ◽  
Open Ocean ◽  
Sea Salt ◽  
The Arctic ◽  
Polar Regions ◽  
Blowing Snow ◽  
In Situ Observations ◽  
Frost Flowers ◽  
Mass Concentrations

Abstract. Sea salt aerosols (SSA) are generated via air bubbles bursting at the ocean surface as well as by wind mobilization of saline snow and frost flowers over sea-ice-covered areas. The relative magnitude of these sources remains poorly constrained over polar regions, affecting our ability to predict their impact on halogen chemistry, cloud formation, and climate. We implement a blowing snow and a frost flower emission scheme in the GEOS-Chem global chemical transport model, which we validate against multiyear (2001–2008) in situ observations of SSA mass concentrations at three sites in the Arctic, two sites in coastal Antarctica, and from the 2008 ICEALOT cruise in the Arctic. A simulation including only open ocean emissions underestimates SSA mass concentrations by factors of 2–10 during winter–spring for all ground-based and ship-based observations. When blowing snow emissions are added, the model is able to reproduce observed wintertime SSA concentrations, with the model bias decreasing from a range of −80 to −34 % for the open ocean simulation to −2 to +9 % for the simulation with blowing snow emissions. We find that the frost flower parameterization cannot fully explain the high wintertime concentrations and displays a seasonal cycle decreasing too rapidly in early spring. Furthermore, the high day-to-day variability of observed SSA is better reproduced by the blowing snow parameterization. Over the Arctic (> 60° N) (Antarctic, > 60° S), we calculate that submicron SSA emissions from blowing snow account for 1.0 Tg yr−1 (2.5 Tg yr−1), while frost flower emissions lead to 0.21 Tg yr−1 (0.25 Tg yr−1) compared to 0.78 Tg yr−1 (1.0 Tg yr−1) from the open ocean. Blowing snow emissions are largest in regions where persistent strong winds occur over sea ice (east of Greenland, over the central Arctic, Beaufort Sea, and the Ross and Weddell seas). In contrast, frost flower emissions are largest where cold air temperatures and open leads are co-located (over the Canadian Arctic Archipelago, coastal regions of Siberia, and off the Ross and Ronne ice shelves). Overall, in situ observations of mass concentrations of SSA suggest that blowing snow is likely to be the dominant SSA source during winter, with frost flowers playing a much smaller role.

scholarly journals Wintertime enhancements of sea salt aerosol in polar regions consistent with a sea-ice source from blowing snow

2016 ◽  
Author(s):  
Jiayue Huang ◽  
Lyatt Jaeglé
Keyword(s):  
Sea Ice ◽  
Open Ocean ◽  
Sea Salt ◽  
The Arctic ◽  
Polar Regions ◽  
Blowing Snow ◽  
In Situ Observations ◽  
Frost Flowers ◽  
Mass Concentrations

Abstract. Sea salt aerosols (SSA) are generated via air bubbles bursting at the ocean surface, as well as by wind mobilization of saline snow and frost flowers over sea-ice covered areas. The relative magnitude of these sources remains poorly constrained over polar regions, affecting our ability to predict their impact on halogen chemistry, cloud formation and climate. We implement a blowing snow and a frost flower emission scheme in the GEOS-Chem global chemical transport model, which we validate against multi-year (2001–2008) in situ observations of SSA mass concentrations at three sites in the Arctic, two sites in coastal Antarctica, as well as during a cruise in the Arctic (ICEALOT, 2008). A simulation including only open ocean emissions underestimates SSA mass concentrations by factors of 2–10 during winter-spring for all ground-based and ship-based observations. When blowing snow emissions are added, the model is able to reproduce observed wintertime SSA concentrations, with the model bias decreasing from a range of −80 % to −34 % for the open ocean simulation to −2 % to +9 % for the simulation with blowing snow emissions. We find that the frost flower parameterization cannot fully explain the high wintertime concentrations and displays a seasonal cycle decreasing too rapidly in early spring. Furthermore, the high day-to-day variability of observed SSA is better reproduced by the blowing snow parameterization. Over the Arctic (Antarctic), we calculate that submicron SSA emissions from blowing snow account for 1.0 (2.5) Tg yr−1, while frost flower emissions lead to 0.25 (0.14) Tg yr−1 compared to 0.78 (1.0) Tg yr−1 from the open ocean. Blowing snow emissions are largest in regions where persistent strong winds occur over sea ice (East of Greenland, over the central Arctic, Beaufort Sea, as well as the Ross and Weddell Seas). In contrast, frost flower emissions are largest where cold air temperatures, open leads and mild winds are co-located (over the Canadian Arctic Archipelago, coastal regions of Siberia, and off the Ross and Ronne ice shelves). Overall, in situ observations of mass concentrations of SSA suggest that blowing snow is likely to be the dominant SSA source during winter, with frost flowers playing a much smaller role.

scholarly journals A Comparative Study of Statistical Techniques for Prediction of Meteorological and Oceanographic Conditions: An Application in Sea Spray Icing

2021 ◽  
Vol 9 (5) ◽  
pp. 539
Author(s):  
Abolfazl Shojaei Shojaei Barjouei ◽  
Masoud Naseri
Keyword(s):  
Monte Carlo ◽  
Daily Basis ◽  
Reanalysis Data ◽  
Coast Guard ◽  
Model Verification ◽  
The Arctic ◽  
Sea Spray ◽  
Absolute Deviation ◽  
Svalbard Archipelago ◽  
Oceanographic Conditions

Environmental conditions in Arctic waters pose challenges to various offshore industrial activities. In this regard, better prediction of meteorological and oceanographic conditions contributes to addressing the challenges by developing economic plans and adopting safe strategies. This study revolved around simulation of meteorological and oceanographic conditions. To this aim, the applications of Bayesian inference, as well as Monte Carlo simulation (MCS) methods including sequential importance sampling (SIS) and Markov Chain Monte Carlo (MCMC) were studied. Three-hourly reanalysis data from the NOrwegian ReAnalysis 10 km (NORA10) for 33 years were used to evaluate the performance of the suggested simulation approaches. The data corresponding to the first 32 years were used to predict the meteorological and oceanographic conditions, and the data corresponding to the following year were used to model verification on a daily basis. The predicted meteorological and oceanographic conditions were then considered as inputs for the newly introduced icing model, namely Marine-Icing model for the Norwegian Coast Guard (MINCOG), to estimate sea spray icing in some regions of the Arctic Ocean, particularly in the sea area between Northern Norway and Svalbard archipelago. The results indicate that the monthly average absolute deviation (AAD) from reanalysis values for the MINCOG estimations with Bayesian, SIS, and MCMC inputs is not greater than 0.13, 0.22, and 0.41 cm/h, respectively.

scholarly journals Pan-Arctic surface ozone: modelling vs. measurements

2020 ◽  
Vol 20 (24) ◽  
pp. 15937-15967
Author(s):  
Xin Yang ◽  
Anne-M. Blechschmidt ◽  
Kristof Bognar ◽  
Audra McClure-Begley ◽  
Sara Morris ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Surface Ozone ◽  
Open Ocean ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Sea Spray ◽  
Blowing Snow ◽  
Model Control

Abstract. Within the framework of the International Arctic Systems for Observing the Atmosphere (IASOA), we report a modelling-based study on surface ozone across the Arctic. We use surface ozone from six sites – Summit (Greenland), Pallas (Finland), Barrow (USA), Alert (Canada), Tiksi (Russia), and Villum Research Station (VRS) at Station Nord (North Greenland, Danish realm) – and ozone-sonde data from three Canadian sites: Resolute, Eureka, and Alert. Two global chemistry models – a global chemistry transport model (parallelised-Tropospheric Offline Model of Chemistry and Transport, p-TOMCAT) and a global chemistry climate model (United Kingdom Chemistry and Aerosol, UKCA) – are used for model data comparisons. Remotely sensed data of BrO from the GOME-2 satellite instrument and ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) at Eureka, Canada, are used for model validation. The observed climatology data show that spring surface ozone at coastal sites is heavily depleted, making ozone seasonality at Arctic coastal sites distinctly different from that at inland sites. Model simulations show that surface ozone can be greatly reduced by bromine chemistry. In April, bromine chemistry can cause a net ozone loss (monthly mean) of 10–20 ppbv, with almost half attributable to open-ocean-sourced bromine and the rest to sea-ice-sourced bromine. However, the open-ocean-sourced bromine, via sea spray bromide depletion, cannot by itself produce ozone depletion events (ODEs; defined as ozone volume mixing ratios, VMRs, < 10 ppbv). In contrast, sea-ice-sourced bromine, via sea salt aerosol (SSA) production from blowing snow, can produce ODEs even without bromine from sea spray, highlighting the importance of sea ice surface in polar boundary layer chemistry. Modelled total inorganic bromine (BrY) over the Arctic sea ice is sensitive to model configuration; e.g. under the same bromine loading, BrY in the Arctic spring boundary layer in the p-TOMCAT control run (i.e. with all bromine emissions) can be 2 times that in the UKCA control run. Despite the model differences, both model control runs can successfully reproduce large bromine explosion events (BEEs) and ODEs in polar spring. Model-integrated tropospheric-column BrO generally matches GOME-2 tropospheric columns within ∼ 50 % in UKCA and a factor of 2 in p-TOMCAT. The success of the models in reproducing both ODEs and BEEs in the Arctic indicates that the relevant parameterizations implemented in the models work reasonably well, which supports the proposed mechanism of SSA production and bromide release on sea ice. Given that sea ice is a large source of SSA and halogens, changes in sea ice type and extent in a warming climate will influence Arctic boundary layer chemistry, including the oxidation of atmospheric elemental mercury. Note that this work dose not necessary rule out other possibilities that may act as a source of reactive bromine from the sea ice zone.

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