Hydroxyl radical and NO<sub><i>x</i></sub> production rates, black carbon concentrations and light‐absorbing impurities in snow from field measurements of light penetration and nadir reflectivity of onshore and offshore coastal Alaskan snow

Reay, H. J.; King, Martin D.; Voisin, Didier; Jacobi, Hans-Werner; Dominé, Florent; Beine, H. J.; Anastasio, Cort; MacArthur, Alasdair; Lee-Taylor, J.

doi:10.1029/2011jd016639

Cited by 64 publications

(123 citation statements)

References 112 publications

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“…Hagler et al (2007) found snow to have a much higher OC to EC ratio (205 : 1) than air (10 : 1), suggesting that snow is additionally influenced by watersoluble gasphase compounds. France et al (2012) demonstrated that black carbon alone could not account for all the absorption seen in the Barrow snowpacks, and an additional absorption by Humic Like Substances (HULIS), part of brown carbon, and other chromophores was necessary to explain variation. Voisin et al (2012) measured HULIS optical properties and reported them to be consistent with aged biomass burning or a possible marine source.…”

Section: Impurities In Snowmentioning

confidence: 99%

Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

et al. 2013

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Abstract. We have measured spectral albedo, as well as ancillary parameters, of seasonal European Arctic snow at Sodankylä, Finland (67°22' N, 26°39' E). The springtime intensive melt period was observed during the Snow Reflectance Transition Experiment (SNORTEX) in April 2009. The upwelling and downwelling spectral irradiance, measured at 290–550 nm with a double monochromator spectroradiometer, revealed albedo values of ~0.5–0.7 for the ultraviolet and visible range, both under clear sky and variable cloudiness. During the most intensive snowmelt period of four days, albedo decreased from 0.65 to 0.45 at 330 nm, and from 0.72 to 0.53 at 450 nm. In the literature, the UV and VIS albedo for clean snow are ~0.97–0.99, consistent with the extremely small absorption coefficient of ice in this spectral region. Our low albedo values were supported by two independent simultaneous broadband albedo measurements, and simulated albedo data. We explain the low albedo values to be due to (i) large snow grain sizes up to ~3 mm in diameter; (ii) meltwater surrounding the grains and increasing the effective grain size; (iii) absorption caused by impurities in the snow, with concentration of elemental carbon (black carbon) in snow of 87 ppb, and organic carbon 2894 ppb, at the time of albedo measurements. The high concentrations of carbon, detected by the thermal–optical method, were due to air masses originating from the Kola Peninsula, Russia, where mining and refining industries are located.

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Section: Impurities In Snowmentioning

confidence: 99%

Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

et al. 2013

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“…2.2 were not considered. In the case of studies considering multiple light-absorbing impurities in the snow or sea ice, France et al (2012) demonstrated how to separate the effects of different light-absorbing impurities from black carbon for snow on sea ice.…”

Section: Snowpack or Sea Ice Thicknessmentioning

confidence: 99%

“…A fixed value of 0.95 for sea ice and 0.89 for snow were determined, based on the values presented by France et al (2012) and Marks and King (2013). In the two papers, g was held constant and σ scatt and σ + abs varied, based on the methods of Lee Taylor and Madronich (2002).…”

Section: Asymmetry Parametermentioning

confidence: 99%

The impact of atmospheric mineral aerosol deposition on the albedo of snow & sea ice: are snow and sea ice optical properties more important than mineral aerosol optical properties?

2016

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Abstract. Knowledge of the albedo of polar regions is crucial for understanding a range of climatic processes that have an impact on a global scale. Light-absorbing impurities in atmospheric aerosols deposited on snow and sea ice by aeolian transport absorb solar radiation, reducing albedo. Here, the effects of five mineral aerosol deposits reducing the albedo of polar snow and sea ice are considered. Calculations employing a coupled atmospheric and snow/sea ice radiativetransfer model (TUV-snow) show that the effects of mineral aerosol deposits are strongly dependent on the snow or sea ice type rather than the differences between the aerosol optical characteristics. The change in albedo between five different mineral aerosol deposits with refractive indices varying by a factor of 2 reaches a maximum of 0.0788, whereas the difference between cold polar snow and melting sea ice is 0.8893 for the same mineral loading. Surprisingly, the thickness of a surface layer of snow or sea ice loaded with the same mass ratio of mineral dust has little effect on albedo. On the contrary, the surface albedo of two snowpacks of equal depth, containing the same mineral aerosol mass ratio, is similar, whether the loading is uniformly distributed or concentrated in multiple layers, regardless of their position or spacing. The impact of mineral aerosol deposits is much larger on melting sea ice than on other types of snow and sea ice. Therefore, the higher input of shortwave radiation during the summer melt cycle associated with melting sea ice accelerates the melt process.

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“…However, light-absorbing impurities, such as black carbon (BC) (e.g. Warren and Wiscombe, 1980;Flanner et al, 2012), dust Painter et al, 2007) and humic-like substances (Hoffer et al, 2006;, impact snow optical properties, especially in the visible range Reay et al, 2012). These impurities are taken into account in TARTES.…”

Section: Impuritiesmentioning

confidence: 99%

Influence of grain shape on light penetration in snow

Libois

Picard²,

France³

et al. 2013

The Cryosphere

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Abstract. The energy budget and the photochemistry of a snowpack depend greatly on the penetration of solar radiation in snow. Below the snow surface, spectral irradiance decreases exponentially with depth with a decay constant called the asymptotic flux extinction coefficient. As with the albedo of the snowpack, the asymptotic flux extinction coefficient depends on snow grain shape. While representing snow by a collection of spherical particles has been successful in the numerical computation of albedo, such a description poorly explains the decrease of irradiance in snow with depth. Here we explore the limits of the spherical representation. Under the assumption of geometric optics and weak absorption by snow, the grain shape can be simply described by two parameters: the absorption enhancement parameter B and the geometric asymmetry factor g G . Theoretical calculations show that the albedo depends on the ratio B/(1−g G ) and the asymptotic flux extinction coefficient depends on the product B(1 − g G ). To understand the influence of grain shape, the values of B and g G are calculated for a variety of simple geometric shapes using ray tracing simulations. The results show that B and (1 − g G ) generally covary so that the asymptotic flux extinction coefficient exhibits larger sensitivity to the grain shape than albedo. In particular it is found that spherical grains propagate light deeper than any other investigated shape. In a second step, we developed a method to estimate B from optical measurements in snow. A multi-layer, two-stream, radiative transfer model, with explicit grain shape dependence, is used to retrieve values of the B parameter of snow by comparing the model to joint measurements of reflectance and irradiance profiles. Such measurements were performed in Antarctica and in the Alps yielding estimates of B between 0.8 and 2.0. In addition, values of B were estimated from various measurements found in the literature, leading to a wider range of values (1.0-9.9) which may be partially explained by the limited accuracy of the data. This work highlights the large variety of snow microstructure and experimentally demonstrates that spherical grains, with B = 1.25, are inappropriate to model irradiance profiles in snow, an important result that should be considered in further studies dedicated to subsurface absorption of short-wave radiation and snow photochemistry.

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Hydroxyl radical and NO_x production rates, black carbon concentrations and light‐absorbing impurities in snow from field measurements of light penetration and nadir reflectivity of onshore and offshore coastal Alaskan snow

Cited by 64 publications

References 112 publications

Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

The impact of atmospheric mineral aerosol deposition on the albedo of snow & sea ice: are snow and sea ice optical properties more important than mineral aerosol optical properties?

Influence of grain shape on light penetration in snow

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Hydroxyl radical and NOx production rates, black carbon concentrations and light‐absorbing impurities in snow from field measurements of light penetration and nadir reflectivity of onshore and offshore coastal Alaskan snow

Cited by 64 publications

References 112 publications

Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

The impact of atmospheric mineral aerosol deposition on the albedo of snow & sea ice: are snow and sea ice optical properties more important than mineral aerosol optical properties?

Influence of grain shape on light penetration in snow

Contact Info

Product

Resources

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Hydroxyl radical and NO_x production rates, black carbon concentrations and light‐absorbing impurities in snow from field measurements of light penetration and nadir reflectivity of onshore and offshore coastal Alaskan snow