The Role of Snow in Controlling Halogen Chemistry and Boundary Layer Oxidation During Arctic Spring: A 1D Modeling Case Study

Ahmed, Shaddy; Thomas, Jennie L.; Tuite, Katie; Stutz, J.; Flocke, Frank; Hornbrook, R. S.; Apel, E. C.; Emmons, L. K.; Helmig, Detlev; Boylan, Patrick; Huey, L. G.; Hall, Samuel R.; Ullmann, Kirk; Cantrell, C. A.; Fried, Alan

doi:10.1029/2021jd036140

Cited by 6 publications

(5 citation statements)

References 113 publications

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“…Piot and von Glasow (2009) used a box model to calculate the required fluxes of halogens to account for the observed effects on ozone in Alert, Canada in early spring, and estimated a Br 2 flux ranging from 5 × 10 7 to 1.5 × 10 9 molecules cm −2 s −1 . Other box and 1D modeling studies estimated maximum emissions of Br 2 of 2 -5 × 10 8 molecules cm −2 s −1 at Utqiagvik, Alaska in March (Ahmed et al, 2022;Wang & Pratt, 2017), within the same order of magnitude of those from previous observation-based estimates from the same site (Custard et al, 2017).…”

supporting

confidence: 68%

Implications of Snowpack Reactive Bromine Production for Arctic Ice Core Bromine Preservation

Zhai,

Swanson,

McConnell

et al. 2023

JGR Atmospheres

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Snowpack emissions are recognized as an important source of gas‐phase reactive bromine in the Arctic and are necessary to explain ozone depletion events in spring caused by the catalytic destruction of ozone by halogen radicals. Quantifying bromine emissions from snowpack is essential for interpretation of ice‐core bromine. We present ice‐core bromine records since the pre‐industrial (1750 CE) from six Arctic locations and examine potential post‐depositional loss of snowpack bromine using a global chemical transport model. Trend analysis of the ice‐core records shows that only the high‐latitude coastal Akademii Nauk (AN) ice core from the Russian Arctic preserves significant trends since pre‐industrial times that are consistent with trends in sea ice extent and anthropogenic emissions from source regions. Model simulations suggest that recycling of reactive bromine on the snow skin layer (top 1 mm) results in 9–17% loss of deposited bromine across all six ice‐core locations. Reactive bromine production from below the snow skin layer and within the snow photic zone is potentially more important, but the magnitude of this source is uncertain. Model simulations suggest that the AN core is most likely to preserve an atmospheric signal compared to five Greenland ice cores due to its high latitude location combined with a relatively high snow accumulation rate. Understanding the sources and amount of photochemically reactive snow bromide in the snow photic zone throughout the sunlit period in the high Arctic is essential for interpreting ice‐core bromine, and warrants further lab studies and field observations at inland locations.

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supporting

confidence: 68%

Implications of Snowpack Reactive Bromine Production for Arctic Ice Core Bromine Preservation

Zhai,

Swanson,

McConnell

et al. 2023

JGR Atmospheres

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“…The study reported excess bromine in the springtime that could not be explained by known particle sources and ascribed it to partitioning of gaseous bromine produced from nonparticulate sources . In the current study, the measured gas-phase bromine could not be explained by particulate bromide alone (as explained below), and therefore, the enrichment of bromide in submicron aerosol particles prior to snowmelt is consistent with snowpack-produced Br 2 and BrCl, leading to atmospheric bromine recycling and the gas-particle partitioning of bromine-containing gases (e.g., HBr, HOBr, BrONO 2 ) …”

Section: Resultssupporting

confidence: 50%

“…75 In the current study, the measured gas-phase bromine could not be explained by particulate bromide alone (as explained below), and therefore, the enrichment of bromide in submicron aerosol particles prior to snowmelt is consistent with snowpack-produced Br 2 and BrCl, leading to atmospheric bromine recycling and the gas-particle partitioning of brominecontaining gases (e.g., HBr, HOBr, BrONO 2 ). 77 The slowdown of reactive bromine chemistry beginning in late April through the end of the study is evident in the measured particulate [Br − ] (Figure 3a). Prior to the onset of snowmelt (April 30−May 10), submicron particle bromide was elevated (0.3−2 ng m −3 ), compared to the levels after the snowmelt.…”

Section: Shutdown Of Reactive Bromine Chemistry In Latementioning

confidence: 93%

Multiphase Reactive Bromine Chemistry during Late Spring in the Arctic: Measurements of Gases, Particles, and Snow

Jeong

McNamara

Barget

et al. 2022

ACS Earth Space Chem.

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Bromine radicals (Br•) cause ozone depletion and mercury deposition in the Arctic atmospheric boundary layer, following Polar sunrise. These Br radicals are primarily formed by the photolysis of molecular bromine (Br 2 ), which is photochemically produced in the snowpack. Recently, it was shown that bromine monoxide (BrO•), formed from the reaction of Br• with ozone, is episodically present until the onset of snowmelt in late Arctic spring. To examine the drivers of this late spring shutdown of reactive bromine chemistry, the gases Br 2 , HOBr, BrO, and BrCl were continuously monitored using chemical ionization mass spectrometry during the spring (March−May 2016) near Utqiagvik, Alaska. On May 10th, all four reactive bromine species fell below levels of detection at the same time that air temperature increased above 0 °C, surface albedo decreased, and snowmelt onset was observed. Prior to the cessation of atmospheric bromine chemistry, local surface snow samples in early May became significantly enriched in bromide, likely due to the slowdown of reactive bromine recycling with continued deposition but decreased emissions from the snowpack. Particulate bromide concentrations were not sufficient to explain the quantities of reactive bromine gases observed and decreased upon snowmelt. Low wind speeds during the weeks preceding the cessation of reactive bromine chemistry point to the lack of a contribution to bromine chemistry from blowing snow. Together, these results further highlight the significance of the surface snowpack in multiphase bromine recycling with important implications as the melt season arrives earlier due to climate change.

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“…The extremely strong near-surface temperature inversion and low speed winds at the surface require a fine vertical grid to model the trapping of pollution from surface sources and also to model potential downwash from lofted sources such as power plants. Therefore, we used both 1-D chemistry-aerosol-transport models ,, with very fine grids and a special version of the Weather Research Forecast - Community Multiscale Air Quality (WRF-CMAQ) model tuned to Fairbanks and coupled with aerosol chemistry and WRF-Chem tuned to Arctic conditions . To model dispersion, we can couple meteorological fields from WRF with a Lagrangian model such as the FLEXible PARTicle dispersion model (FLEXPART) .…”

Section: Experimental/methodsmentioning

confidence: 99%

Overview of the Alaskan Layered Pollution and Chemical Analysis (ALPACA) Field Experiment

Simpson,

Mao,

Fochesatto

et al. 2024

ACS EST Air

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The Alaskan Layered Pollution And Chemical Analysis (ALPACA) field experiment was a collaborative study designed to improve understanding of pollution sources and chemical processes during winter (cold climate and low-photochemical activity), to investigate indoor pollution, and to study dispersion of pollution as affected by frequent temperature inversions. A number of the research goals were motivated by questions raised by residents of Fairbanks, Alaska, where the study was held. This paper describes the measurement strategies and the conditions encountered during the January and February 2022 field experiment, and reports early examples of how the measurements addressed research goals, particularly those of interest to the residents. Outdoor air measurements showed high concentrations of particulate matter and pollutant gases including volatile organic carbon species. During pollution events, low winds and extremely stable atmospheric conditions trapped pollution below 73 m, an extremely shallow vertical scale. Tethered-balloonbased measurements intercepted plumes aloft, which were associated with power plant point sources through transport modeling. Because cold climate residents spend much of their time indoors, the study included an indoor air quality component, where measurements were made inside and outside a house to study infiltration and indoor sources. In the absence of indoor activities such as cooking and/or heating with a pellet stove, indoor particulate matter concentrations were lower than outdoors; however, cooking and pellet stove burns often caused higher indoor particulate matter concentrations than outdoors. The mass-normalized particulate matter oxidative potential, a health-relevant property measured here by the reactivity with dithiothreiol, of indoor particles varied by continued...

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The Role of Snow in Controlling Halogen Chemistry and Boundary Layer Oxidation During Arctic Spring: A 1D Modeling Case Study

Abstract: Halogen chemistry has a large impact on tropospheric chemistry in the polar regions (e.g.,

Cited by 6 publications

References 113 publications

Implications of Snowpack Reactive Bromine Production for Arctic Ice Core Bromine Preservation

Implications of Snowpack Reactive Bromine Production for Arctic Ice Core Bromine Preservation

Multiphase Reactive Bromine Chemistry during Late Spring in the Arctic: Measurements of Gases, Particles, and Snow

Overview of the Alaskan Layered Pollution and Chemical Analysis (ALPACA) Field Experiment

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