scholarly journals Observations and the source investigations of boundary layer BrO in Ny-Ålesund Arctic

2017 ◽  
Author(s):  
Yuhan Luo ◽  
Fuqi Si ◽  
Haijin Zhou ◽  
Ke Dou ◽  
Yi Liu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Loss Rate ◽  
Elemental Mercury ◽  
Optical Absorption Spectroscopy ◽  
Polar Regions ◽  
Gaseous Elemental Mercury ◽  
Bay Area ◽  
Boundary Layer Ozone ◽  
Kings Bay

Abstract. Bromine monoxide is a reactive halogen species which has crucial impact on the chemistry of the tropospheric polar boundary layer. During polar spring, BrO enhancement can be detected in both northern and southern Polar Regions, while the boundary layer ozone depletion events occur. A considerable challenge for understanding enhanced BrO and the associated ODEs is the difficulty of real-time observations. In this study, a typical process of enhanced bromine and depleted ozone in late April, 2015 at Ny-Ålesund boundary layer was observed using ground-based Multi Axis-Differential Optical Absorption Spectroscopy (MAX-DOAS) technique. The results showed that there were as high as 8 × 1014 molecular cm−2 BrO slant columns above the Kings Bay area in 26 April. Considering meteorology, sea ice distribution and air mass history, the floating sea ice in the Kings Bay area was considered as the major source of this bromine enhancement event. During this period, the boundary layer ozone and gaseous elemental mercury (GEM) was synchronously reduced by 85 % and 90 % separately. The kinetic calculation showed that the ozone loss rate is 10.3 ppbv h−1, which is extremely high compared to other area. The GEM loss rate is about 0.25 ng m−3 h−1. The oxidized GEM may directly deposit to snow/ice and thereby influence the polar ecosystem.

scholarly journals Observations and source investigations of the boundary layer bromine monoxide (BrO) in the Ny-Ålesund Arctic

2018 ◽  
Vol 18 (13) ◽  
pp. 9789-9801 ◽  
Author(s):  
Yuhan Luo ◽  
Fuqi Si ◽  
Haijin Zhou ◽  
Ke Dou ◽  
Yi Liu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Elemental Mercury ◽  
Arctic Sea Ice ◽  
Optical Absorption Spectroscopy ◽  
Mercury Deposition ◽  
Gaseous Elemental Mercury ◽  
Bay Area ◽  
Short Period ◽  
Kings Bay

Abstract. During polar spring, the presence of reactive bromine in the polar boundary layer is considered to be the main cause of ozone depletion and mercury deposition. However, many uncertainties still remain regarding understanding the mechanisms of the chemical process and source of the bromine. As Arctic sea ice has recently been dramatically reduced, it is critical to investigate the mechanisms using more accurate measurements with higher temporal and spatial resolution. In this study, a typical process of enhanced bromine and depleted ozone in the Ny-Ålesund boundary layer in late April 2015 was observed by applying ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) technique. The results showed that there were bromine monoxide (BrO) slant columns as high as 5.6 × 1014 molec cm−2 above the Kings Bay area on 26 April. Meanwhile, the boundary layer ozone and gaseous elemental mercury (GEM) were synchronously reduced by 85 and 90 %, respectively. Based on the meteorology, sea ice distribution and air mass history, the sea ice in the Kings Bay area, which emerged for only a very short period of time when the enhanced BrO was observed, was considered to be the major source of this bromine enhancement event. The oxidized GEM may be directly deposited onto snow/ice and thereby influence the polar ecosystem.

scholarly journals A synthesis of atmospheric mercury depletion event chemistry linking atmosphere, snow and water

2007 ◽  
Vol 7 (4) ◽  
pp. 10837-10931 ◽  
Author(s):  
A. Steffen ◽  
T. Douglas ◽  
M. Amyot ◽  
P. Ariya ◽  
K. Aspmo ◽  
...  
Keyword(s):  
Sea Ice ◽  
Current Knowledge ◽  
Kinetic Studies ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Polar Regions ◽  
Environmental Media ◽  
Gaseous Elemental Mercury ◽  
History Of

Abstract. It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review the history of Hg in Polar Regions, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the roles that the snow pack, oceans, fresh water and the sea ice play in the cycling of Hg are presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the same form in the snow. Kinetic studies undertaken have demonstrated that bromine is the major oxidant depleting Hg in the atmosphere. Modeling results demonstrate that there is a significant deposition of Hg to Polar Regions as a result of AMDEs. Models have also shown that Hg is readily transported to the Arctic from source regions, at times during springtime when this environment is actively transforming Hg from the atmosphere to the snow and ice surfaces. The presence of significant amounts of methyl Hg in snow in the Arctic surrounding AMDEs is important because this species is the link between the environment and impacts to wildlife and humans. Further, much work on methylation and demethylation processes have occurred but are not yet fully understood. Recent changes in the climate and sea ice cover in Polar Regions are likely to have strong effects on the cycling of Hg in this environment; however more research is needed to understand Hg processes in order to formulate meaningful predictions of these changes. Mercury, Atmospheric mercury depletion events (AMDE), Polar, Arctic, Antarctic, Ice

scholarly journals Enhanced tropospheric BrO over Antarctic sea ice in mid winter observed by MAX-DOAS on board the research vessel Polarstern

2007 ◽  
Vol 7 (12) ◽  
pp. 3129-3142 ◽  
Author(s):  
T. Wagner ◽  
O. Ibrahim ◽  
R. Sinreich ◽  
U. Frieß ◽  
R. von Glasow ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Vertical Mixing ◽  
Satellite Observations ◽  
Research Vessel ◽  
Optical Absorption Spectroscopy ◽  
Back Trajectory ◽  
First Year ◽  
Polar Regions ◽  
Near Surface

Abstract. We present Multi AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS) observations of tropospheric BrO carried out on board the German research vessel Polarstern during the Antarctic winter 2006. Polarstern entered the area of first year sea ice around Antarctica on 24 June 2006 and stayed within this area until 15 August 2006. For the period when the ship cruised inside the first year sea ice belt, enhanced BrO concentrations were almost continuously observed. Outside the first year sea ice belt, typically low BrO concentrations were found. Based on back trajectory calculations we find a positive correlation between the observed BrO differential slant column densities (ΔSCDs) and the duration for which the air masses had been in contact with the sea ice surface prior to the measurement. While we can not completely rule out that in several cases the highest BrO concentrations might be located close to the ground, our observations indicate that the maximum BrO concentrations might typically exist in a (possibly extended) layer around the upper edge of the boundary layer. Besides the effect of a decreasing pH of sea salt aerosol with altitude and therefore an increase of BrO with height, this finding might be also related to vertical mixing of air from the free troposphere with the boundary layer, probably caused by convection over the warm ocean surface at polynyas and cracks in the ice. Strong vertical gradients of BrO and O3 could also explain why we found enhanced BrO levels almost continuously for the observations within the sea ice. Based on our estimated BrO profiles we derive BrO mixing ratios of several ten ppt, which is slightly higher than many existing observations. Our observations indicate that enhanced BrO concentrations around Antarctica exist about one month earlier than observed by satellite instruments. From detailed radiative transfer simulations we find that MAX-DOAS observations are up to about one order of magnitude more sensitive to near-surface BrO than satellite observations. In contrast to satellite observations the MAX-DOAS sensitivity hardly decreases for large solar zenith angles and is almost independent from the ground albedo. Thus this technique is very well suited for observations in polar regions close to the solar terminator. For large periods of our measurements the solar elevation was very low or even below the horizon. For such conditions, most reactive Br-compounds might exist as Br2 molecules and ozone destruction and the removal of reactive bromine compounds might be substantially reduced.

scholarly journals A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow

2008 ◽  
Vol 8 (6) ◽  
pp. 1445-1482 ◽  
Author(s):  
A. Steffen ◽  
T. Douglas ◽  
M. Amyot ◽  
P. Ariya ◽  
K. Aspmo ◽  
...  
Keyword(s):  
Sea Ice ◽  
Current Knowledge ◽  
Kinetic Studies ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Polar Regions ◽  
Environmental Media ◽  
Gaseous Elemental Mercury ◽  
Low Concentrations

Abstract. It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the same form in the snow. Kinetic studies undertaken have demonstrated that bromine is the major oxidant depleting Hg in the atmosphere. Modeling results demonstrate that there is a significant deposition of Hg to Polar Regions as a result of AMDEs. Models have also shown that Hg is readily transported to the Arctic from source regions, at times during springtime when this environment is actively transforming Hg from the atmosphere to the snow and ice surfaces. The presence of significant amounts of methyl Hg in snow in the Arctic surrounding AMDEs is important because this species is the link between the environment and impacts to wildlife and humans. Further, much work on methylation and demethylation processes has occurred but these processes are not yet fully understood. Recent changes in the climate and sea ice cover in Polar Regions are likely to have strong effects on the cycling of Hg in this environment; however more research is needed to understand Hg processes in order to formulate meaningful predictions of these changes.

scholarly journals Gaseous elemental mercury depletion events observed at Cape Point during 2007–2008

2010 ◽  
Vol 10 (3) ◽  
pp. 1121-1131 ◽  
Author(s):  
E.-G. Brunke ◽  
C. Labuschagne ◽  
R. Ebinghaus ◽  
H. H. Kock ◽  
F. Slemr
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Chemical Mechanism ◽  
Polar Regions ◽  
Gaseous Elemental Mercury ◽  
Transport Distance ◽  
Gaseous Mercury ◽  
Urban Emissions

Abstract. Gaseous mercury in the marine boundary layer has been measured with a 15 min temporal resolution at the Global Atmosphere Watch station Cape Point since March 2007. The most prominent features of the data until July 2008 are the frequent occurrences of pollution (PEs) and depletion events (DEs). Both types of events originate mostly within a short transport distance (up to about 100 km), which are embedded in air masses ranging from marine background to continental. The Hg/CO emission ratios observed during the PEs are within the range reported for biomass burning and industrial/urban emissions. The depletion of gaseous mercury during the DEs is in many cases almost complete and suggests an atmospheric residence time of elemental mercury as short as a few dozens of hours, which is in contrast to the commonly used estimate of approximately 1 year. The DEs observed at Cape Point are not accompanied by simultaneous depletion of ozone which distinguishes them from the halogen driven atmospheric mercury depletion events (AMDEs) observed in Polar Regions. Nonetheless, DEs similar to those observed at Cape Point have also been observed at other places in the marine boundary layer. Additional measurements of mercury speciation and of possible mercury oxidants are hence called for to reveal the chemical mechanism of the newly observed DEs and to assess its importance on larger scales.

scholarly journals The role of open lead interactions in atmospheric ozone variability between Arctic coastal and inland sites

Elem Sci Anth ◽  
2016 ◽  
Vol 4 ◽  
Author(s):  
Peter K. Peterson ◽  
Kerri A. Pratt ◽  
William R. Simpson ◽  
Son V. Nghiem ◽  
Lemuel X. Pérez Pérez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
Optical Absorption Spectroscopy ◽  
Atmospheric Ozone ◽  
Vertical Profiles ◽  
Large Spatial Scale ◽  
Near Surface ◽  
Air Masses

Abstract Boundary layer atmospheric ozone depletion events (ODEs) are commonly observed across polar sea ice regions following polar sunrise. During March-April 2005 in Alaska, the coastal site of Barrow and inland site of Atqasuk experienced ODEs (O3< 10 nmol mol-1) concurrently for 31% of the observations, consistent with large spatial scale ozone depletion. However, 7% of the time ODEs were exclusively observed inland at Atqasuk. This phenomenon also occurred during one of nine flights during the BRomine, Ozone, and Mercury EXperiment (BROMEX), when atmospheric vertical profiles at both sites showed near-surface ozone depletion only at Atqasuk on 28 March 2012. Concurrent in-flight BrO measurements made using nadir scanning differential optical absorption spectroscopy (DOAS) showed the differences in ozone vertical profiles at these two sites could not be attributed to differences in locally occurring halogen chemistry. During both studies, backward air mass trajectories showed that the Barrow air masses observed had interacted with open sea ice leads, causing increased vertical mixing and recovery of ozone at Barrow and not Atqasuk, where the air masses only interacted with tundra and consolidated sea ice. These observations suggest that, while it is typical for coastal and inland sites to have similar ozone conditions, open leads may cause heterogeneity in the chemical composition of the springtime Arctic boundary layer over coastal and inland areas adjacent to sea ice regions.

Evaluation of regional NWP results for sea ice covered Bothnia Bay (Baltic Sea) in winter 2020.

2021 ◽  
Author(s):  
Marta Wenta ◽  
Agnieszka Herman
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Sea Ice ◽  
Surface Temperature ◽  
Atmospheric Boundary Layer ◽  
Baltic Sea ◽  
Polar Regions ◽  
Near Surface ◽  
Accurate Representation ◽  
Complex Processes

<p>The ongoing development of NWP (Numerical Weather Prediction) models and their increasing horizontal resolution have significantly improved forecasting capabilities. However, in the polar regions models struggle with the representation of near-surface atmospheric properties and the vertical structure of the atmospheric boundary layer (ABL) over sea ice. Particularly difficult to resolve are near-surface temperature, wind speed, and humidity, along with diurnal changes of those properties. Many of the complex processes happening at the interface of sea ice and atmosphere, i.e. vertical fluxes, turbulence, atmosphere - surface coupling are poorly parameterized or not represented in the models at all. Limited data coverage and our poor understanding of the complex processes taking place in the polar ABL limit the development of suitable parametrizations. We try to contribute to the ongoing effort to improve the forecast skill in polar regions through the analysis of unmanned aerial vehicles (UAVs) and automatic weather station (AWS) atmospheric measurements from the coastal area of Bothnia Bay (Wenta et. al., 2021), and the application of those datasets for the analysis of regional NWP models' forecasts. </p><p>Data collected during HAOS (Hailuoto Atmospheric Observations over Sea ice) campaign (Wenta et. al., 2021) is used for the evaluation of regional NWP models results from AROME (Applications of Research to Operations at Mesoscale) - Arctic, HIRLAM (High Resolution Limited Area Model) and WRF (Weather Research and Forecasting). The presented analysis focuses on 27 Feb. 2020 - 2 Mar. 2020, the time of the HAOS campaign, shortly after the formation of new, thin sea ice off the westernmost point of Hailuoto island.  Throughout the studied period weather conditions changed from very cold (-14℃), dry and cloud-free to warmer (~ -5℃), more humid and opaquely cloudy. We evaluate models’ ability to correctly resolve near-surface temperature, humidity, and wind speed, along with vertical changes of temperature and humidity over the sea ice. It is found that generally, models struggle with an accurate representation of surface-based temperature inversions, vertical variations of humidity, and temporal wind speed changes. Furthermore, a WRF Single Columng Model (SCM) is launched to study whether specific WRF planetary boundary layer parameterizations (MYJ, YSU, MYNN, QNSE), vertical resolution, and more accurate representation of surface conditions increase the WRF model’s ability to resolve the ABL above sea ice in the Bay of Bothnia. Experiments with WRF SCM are also used to determine the possible reasons behind model’s biases. Preliminary results show that accurate representation of sea ice conditions, including thickness, surface temperature, albedo, and snow coverage is crucial for increasing the quality of NWP models forecasts. We emphasize the importance of further development of parametrizations focusing on the processes at the sea ice-atmosphere interface.</p><p> </p><p>Reference:</p><p>Wenta, M., Brus, D., Doulgeris, K., Vakkari, V., and Herman, A.: Winter atmospheric boundary layer observations over sea ice in the coastal zone of the Bay of Bothnia (Baltic Sea), Earth Syst. Sci. Data, 13, 33–42, https://doi.org/10.5194/essd-13-33-2021, 2021. </p><p><br><br><br><br><br><br></p>

scholarly journals Bromide and other ions in the snow, firn air, and atmospheric boundary layer at Summit during GSHOX

2010 ◽  
Vol 10 (5) ◽  
pp. 13609-13642 ◽  
Author(s):  
J. E. Dibb ◽  
L. D. Ziemba ◽  
J. Luxford ◽  
P. Beckman
Keyword(s):  
Boundary Layer ◽  
Arctic Basin ◽  
Elemental Mercury ◽  
The Arctic ◽  
Free Troposphere ◽  
Gaseous Elemental Mercury ◽  
Mixing Ratios ◽  
Summer Time ◽  
Trace Concentrations ◽  
Photochemical Activation

Abstract. Measurements of gas phase soluble bromide in the boundary layer and in firn air, and Br− in aerosol and snow, were made at Summit, Greenland (72.5° N, 38.4° W, 3200 m a.s.l.) as part of a larger investigation into the influence of Br chemistry on HOx cycling. The soluble bromide measurements confirm that photochemical activation of Br− in the snow causes release of active Br to the overlying air despite trace concentrations of Br− in the snow (means 15 and 8 nmol Br− kg−1 of snow in 2007 and 2008, respectively). Mixing ratios of soluble bromide above the snow were also found to be very small (mean <1 ppt both years, with maxima of 3 and 4 ppt in 2007 and 2008, respectively), but these levels clearly oxidize and deposit long-lived gaseous elemental mercury and may perturb HOx partitioning. Concentrations of Br− in surface snow tended to increase/decrease in parallel with the specific activities of the aerosol-associated radionuclides 7Be and 210Pb. Earlier work has shown that ventilation of the boundary layer causes simultaneous increases in 7Be and 210Pb at Summit, suggesting there is a pool of Br in the free troposphere above Summit in summer time. Speciation and the source of this free tropospheric Br are not well constrained, but we suggest it may be linked to extensive regions of active Br chemistry in the Arctic basin which are known to cause ozone and mercury depletion events shortly after polar sunrise. If this hypothesis is correct, it implies persistence of the free troposphere Br− for several months after peak Br activation in March/April. Alternatively, there may be a~ubiquitous pool of Br− in the free troposphere, sustained by currently unknown sources and processes.

Tropospheric polar BrO derived from S5-P/TROPOMI

2021 ◽  
Author(s):  
Moritz Schöne ◽  
Holger Sihler ◽  
Simon Warnach ◽  
Christian Borger ◽  
Steffen Beirle ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Spatiotemporal Variability ◽  
Optical Absorption Spectroscopy ◽  
Polar Regions ◽  
Satellite Measurements ◽  
Ice Coverage ◽  
Meteorological Influences ◽  
Boundary Layer Ozone ◽  
Catalytic Ozone ◽  
Better Than

&lt;p&gt;Halogen radicals can drastically alter the atmospheric chemistry. In the polar regions, this is made evident by the ozone desctruction in the stratosphere (ozone hole) but also by localized destruction of boundary layer ozone during polar springs. These recurrent episodes of catalytic ozone depletion are caused by enhanced concentrations of reactive bromine compounds. The proposed mechanism by which these are released into the atmosphere is called bromine explosion - reactive bromine is formed autocatalytically from the condensed phase.&lt;/p&gt;&lt;p&gt;The spatial resolution of S-5P/TROPOMI of up to 3,5 km x 5.5 km&amp;#178; allows improved localization and a finer specification of these events compared to previous satellite measurements. Together with the better than daily coverage over the polar regions, this allows investigations of the spatiotemporal variability of enhanced BrO levels and their relation to different possible bromine sources and release mechanisms.&lt;/p&gt;&lt;p&gt;Here, we present tropospheric BrO column densities retrieved from TROPOMI measurements using Differential Optical Absorption Spectroscopy (DOAS). We developed an algorithm capable of separating tropospheric and stratospheric partial columns without further external (model) input only relying on measured NO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;&lt;/sup&gt;and O&lt;sub&gt;3&lt;/sub&gt;, by utilizing a modified version of a k-means clustering and other methods from statistical data analysis.&lt;/p&gt;&lt;p&gt;Selected events from the polar springs in 2019 and 2020 are further analyzed and discussed with regards to sea ice coverage and meteorological influences.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document