Relationship between snow microstructure and  physical and chemical processes

Bartels-Rausch, Thorsten; Jacobi, Hans-Werner; Kahan, Tara F.; Thomas, Jennie L.; Thomson, Erik S.; Abbatt, Jonathan P. D.; Ammann, Markus; Blackford, Jane R.; Bluhm, Hendrik; Boxe, C. S.; Dominé, Florent; Frey, M. M.; Gladich, Ivan; Guzmán, Marcelo I.; Heger, Dominik; Huthwelker, T.; Klán, Petr; Kuhs, Werner F.; Kuo, M. H.; Maus, Sönke; Moussa, Samar G.; McNeill, V. Faye; Newberg, John T.; Pettersson, Jan B. C.; Roeselová, Martina; Sodeau, John R.

doi:10.5194/acpd-12-30409-2012

Cited by 33 publications

(55 citation statements)

References 377 publications

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“…There is now consensus that NO x emissions are an essential component of air-snow cycling of oxidised nitrogen species above the polar ice sheets and snow-covered surfaces in the mid-latitudes (Honrath et al, 2000;Grannas et al, 2007;Davis et al, 2008;Frey et al, 2009b). However, the quantitative understanding of NO x emissions from snow is still incomplete and parameterizations for use in global chemistryclimate models are either non-existent or not reflecting recent progress from lab and field studies (Bartels-Rausch et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

The diurnal variability of atmospheric nitrogen oxides (NO and NO<sub>2</sub>) above the Antarctic Plateau driven by atmospheric stability and snow emissions

et al. 2013

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Abstract. Atmospheric nitrogen oxides (NO and NO2) were observed at Dome C, East Antarctica (75.1° S, 123.3° E, 3233 m), for a total of 50 days, from 10 December 2009 to 28 January 2010. Average (±1σ) mixing ratios at 1.0 m of NO and NO2, the latter measured for the first time on the East Antarctic Plateau, were 111 (±89) and 98 (±89) pptv, respectively. Atmospheric mixing ratios are on average comparable to those observed previously at South Pole, but in contrast show strong diurnal variability: a minimum around local noon and a maximum in the early evening coincide with the development and collapse of a convective boundary layer. The asymmetric diurnal cycle of NOx concentrations and likely any other chemical tracer with a photolytic surface source is driven by the turbulent diffusivity and height of the atmospheric boundary layer, with the former controlling the magnitude of the vertical flux and the latter the size of the volume into which snow emissions are transported. In particular, the average (±1σ) NOx emission flux from 22 December 2009 to 28 January 2010, estimated from atmospheric concentration gradients, was 8.2 (±7.4) × 1012 molecule m−2 s−1 belongs to the largest values measured so far in the polar regions and explains the 3-fold increase in mixing ratios in the early evening when the boundary layer becomes very shallow. Dome C is likely not representative for the entire East Antarctic Plateau but illustrates the need of an accurate description of the boundary layer above snow in atmospheric chemistry models. A simple nitrate photolysis model matches the observed median diurnal NOx flux during the day but has significant low bias during the night. The difference is significant taking into account the total random error in flux observations and model uncertainties due to the variability of NO3− concentrations in snow and potential contributions from NO2− photolysis. This highlights uncertainties in the parameterization of the photolytic NOx source in natural snowpacks, such as the poorly constrained quantum yield of nitrate photolysis. A steady-state analysis of the NO2 : NO ratios indicates that peroxy (HO2 + RO2) or other radical concentrations in the boundary layer of Dome C are either higher than measured elsewhere in the polar regions or other processes leading to enhanced NO2 have to be invoked. These results confirm the existence of a strongly oxidising canopy enveloping the East Antarctic Plateau in summer.

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Section: Introductionmentioning

confidence: 99%

The diurnal variability of atmospheric nitrogen oxides (NO and NO<sub>2</sub>) above the Antarctic Plateau driven by atmospheric stability and snow emissions

et al. 2013

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“…The adsorptive uptake of trace gases to ice has been reviewed previously by Girardet and Toubin (2001), Abbatt (2003), Huthwelker et al (2006), and Bartels-Rausch et al (2012), and summarized in the IUPAC evaluation . Although a majority of the laboratory studies of airice chemical interactions in the literature focus on this topic, significant uncertainty still exists at the molecular level regarding the identity of the adsorption site, the state of the adsorbate on the surface, and the nature of the adsorbatesubstrate interactions.…”

Section: Molecular-level Picturementioning

confidence: 99%

“…strongly influence the processing of organic species in environmental snow and ices. For a full review of this subject please see Bartels-Rausch et al (2012). The properties of these media and the rates and chemical mechanisms of processes occurring there are still poorly constrained.…”

Section: Outlook and Further Questionsmentioning

confidence: 99%

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Organics in environmental ices: sources, chemistry, and impacts

et al. 2012

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Abstract. The physical, chemical, and biological processes involving organics in ice in the environment impact a number of atmospheric and biogeochemical cycles. Organic material in snow or ice may be biological in origin, deposited from aerosols or atmospheric gases, or formed chemically in situ. In this manuscript, we review the current state of knowledge regarding the sources, properties, and chemistry of organic materials in environmental ices. Several outstanding questions remain to be resolved and fundamental data gathered before an accurate model of transformations and transport of organic species in the cryosphere will be possible. For example, more information is needed regarding the quantitative impacts of chemical and biological processes, ice morphology, and snow formation on the fate of organic material in cold regions. Interdisciplinary work at the interfaces of chemistry, physics and biology is needed in order to fully characterize the nature and evolution of organics in the cryosphere and predict the effects of climate change on the Earth's carbon cycle.

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“…However, in these field studies temperatures approached (and even exceeded) the melting point of ice, and consequently the snow held liquid water. Even the presence of a small fraction of liquid in wet snow can significantly modify the trace gassnow interaction, as both adsorption to the solid ice surface and dissolution into the liquid fraction might occur simultaneously (Choi et al, 2000;Bartels-Rausch et al, 2012b). Consequently, it was found that using the air-ice partitioning coefficient to model transport of semi-volatile organics in snow largely underestimated the diffusivities, questioning the application of these gas-solid partitioning data to derive the effective diffusivity for such wet snows (Herbert et al, 2006a,b).…”

Section: Wet Snowmentioning

confidence: 99%

Diffusion of volatile organics through porous snow: impact of surface adsorption and grain boundaries

et al. 2013

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Abstract. Release of trace gases from surface snow on earth drives atmospheric chemistry, especially in the polar regions. The gas-phase diffusion of methanol and of acetone through the interstitial air of snow was investigated in a well-controlled laboratory study in the temperature range of 223 to 263 K. The aim of this study was to evaluate how the structure of the snowpack, the interaction of the trace gases with the snow surface, and the grain boundaries influence the diffusion on timescales up to 1 h. The diffusive loss of these two volatile organics into packed snow samples was measured using a chemical ionization mass spectrometer. The structure of the snow was analysed by means of X-ray-computed micro-tomography. The observed diffusion profiles could be well described based on gas-phase diffusion and the known structure of the snow sample at temperatures &geq; 253 K. At colder temperatures, surface interactions start to dominate the diffusive transport. Parameterizing these interactions in terms of adsorption to the solid ice surface, i.e. using temperature-dependent air–ice partitioning coefficients, better described the observed diffusion profiles than the use of air–liquid partitioning coefficients. No changes in the diffusive fluxes were observed by increasing the number of grain boundaries in the snow sample by a factor of 7, indicating that for these volatile organic trace gases, uptake into grain boundaries does not play a role on the timescale of diffusion through porous surface snow. For this, a snow sample with an artificially high amount of ice grains was produced and the grain boundary surface measured using thin sections. In conclusion, we have shown that the diffusivity can be predicted when the structure of the snowpack and the partitioning of the trace gas to solid ice is known.

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Relationship between snow microstructure and physical and chemical processes

Cited by 33 publications

References 377 publications

The diurnal variability of atmospheric nitrogen oxides (NO and NO<sub>2</sub>) above the Antarctic Plateau driven by atmospheric stability and snow emissions

The diurnal variability of atmospheric nitrogen oxides (NO and NO<sub>2</sub>) above the Antarctic Plateau driven by atmospheric stability and snow emissions

Organics in environmental ices: sources, chemistry, and impacts

Diffusion of volatile organics through porous snow: impact of surface adsorption and grain boundaries

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Relationship between snow microstructure and physical and chemical processes

Cited by 33 publications

References 377 publications

The diurnal variability of atmospheric nitrogen oxides (NO and NO&lt;sub&gt;2&lt;/sub&gt;) above the Antarctic Plateau driven by atmospheric stability and snow emissions

The diurnal variability of atmospheric nitrogen oxides (NO and NO&lt;sub&gt;2&lt;/sub&gt;) above the Antarctic Plateau driven by atmospheric stability and snow emissions

Organics in environmental ices: sources, chemistry, and impacts

Diffusion of volatile organics through porous snow: impact of surface adsorption and grain boundaries

Contact Info

Product

Resources

About

The diurnal variability of atmospheric nitrogen oxides (NO and NO<sub>2</sub>) above the Antarctic Plateau driven by atmospheric stability and snow emissions

The diurnal variability of atmospheric nitrogen oxides (NO and NO<sub>2</sub>) above the Antarctic Plateau driven by atmospheric stability and snow emissions