Attenuation of lateral propagating light in sea ice measured with an artificial lamp in winter Arctic

Zhao, Jinping; Li, T.; Barber, David G.; Ren, Juanjuan; Pućko, Monika; Li, S.-J.; Li, X.

doi:10.1016/j.coldregions.2009.12.006

Cited by 8 publications

(6 citation statements)

References 28 publications

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“…Nevertheless, it is challenging to estimate C from the observations of ice properties. The horizontal extinction of light was found to be increasing with bulk salinity [ Zhao et al ., ] which is an indicator of brine volume. Trodahl et al .…”

Section: Discussionmentioning

confidence: 99%

“…Trodahl et al . [] found that light transfer could be described by assuming a scattering coefficient that is greater horizontally than vertically, which manifests itself in a greater extinction of “laterally propagating light” [ Zhao et al ., ]. The stronger extinction of light traveling horizontally changes the radiance distribution in such a way that the resulting light field is more downward directed [ Trodahl et al ., ] (Figure ).…”

Section: Introductionmentioning

confidence: 99%

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The anisotropic scattering coefficient of sea ice

2014

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Radiative transfer in sea ice is subject to anisotropic, multiple scattering. The impact of anisotropy on the light field under sea ice was found to be substantial and has been quantified. In this study, a large data set of irradiance and radiance measurements under sea ice has been acquired with a Remotely Operated Vehicle (ROV) in the central Arctic. Measurements are interpreted in the context of numerical radiative transfer calculations, laboratory experiments, and microstructure analysis. The ratio of synchronous measurements of transmitted irradiance to radiance shows a clear deviation from an isotropic under-ice light field. We find that the angular radiance distribution under sea ice is more downward directed than expected for an isotropic light field. This effect can be attributed to the anisotropic scattering coefficient within sea ice. Assuming an isotropic radiance distribution under sea ice leads to significant errors in light-field modeling and the interpretation of radiation measurements. Quantification of the light field geometry is crucial for correct conversion of radiance data acquired by Autonomous Underwater Vehicles (AUVs) and ROVs.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The anisotropic scattering coefficient of sea ice

2014

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“…This may not be surprising, because the subglacial environment beneath cold-based glaciers is similar in many respects to more familiar endolithic environments. Similar to other endolithic habitats (e.g., cryptoendolithic and hypoendolithic habitats), the subglacial environment is shielded from incoming solar radiation, in this case by the light-attenuating effect of the surrounding ice (e.g., Zhao et al 2010) or sediment. However, oxygen depletion or anoxia may be more prevalent in subglacial environments than in other crypto/ hypoendolithic environments, particularly beneath coldbased glaciers where replenishment by oxygenated supraglacial meltwater does not occur.…”

Section: Biogeochemical Alteration Since Burialmentioning

confidence: 99%

Stable isotope evidence for the biogeochemical transformation of ancient organic matter beneath Suess Glacier, Antarctica

Barker

Grottoli

Lyons

2018

Arctic, Antarctic, and Alpine Research

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Glaciers overrun organic matter (OM) during periods of advance, making this overrun OM available as a metabolic substrate for subglacial microbes. The biogeochemical fate of this overrun OM remains poorly understood, ultimately limiting our understanding of subglacial biogeochemical cycling, particularly for cold-based glaciers. This study presents evidence for the biogeochemical transformation of algal mat material that was overrun by a cold-based glacier (Suess Glacier, Taylor Valley, Antarctica) during its advance 4840-3570 years BP. We use a suite of stable isotope analyses to show that active nitrogen cycling has depleted N-isotope values to amongst the lowest reported in Taylor Valley (-15.59 ‰) from an initial value of~-1.88 ‰, while potentially depleting C-isotope values by 2.46 ‰. While this study examines biogeochemical conditions beneath a single glacier, all glaciers export meltwater during the melt season that may host algae and other OM in proglacial streams and lakes that may be overridden during glacier advance. As such, subglacial nitrogen cycling detected here may represent processes that occur in cold zones beneath glaciers generally.

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“…[ Maffione et al, 1998;Voss et al, 1992;Zhao et al, 2010] used active measurements in drilled ice to measure the point spread function, beam spread function and horizontal light attenuation. These methods have in common that they have to be operated manually and thereby take significantly more resources compared to continuous measurements on automated platforms.…”

Section: Introductionmentioning

confidence: 99%

New insights into radiative transfer in sea ice derived from autonomous ice internal measurements

Katlein¹,

Valcic²,

Lambert-Girard³

et al. 2020

Preprint

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Abstract. The radiative transfer of short-wave solar radiation through the sea ice cover of the polar oceans is a crucial aspect of energy partitioning at the atmosphere-ice-ocean interface. A detailed understanding of how sunlight is reflected and transmitted by the sea ice cover is needed for an accurate representation of critical processes in climate and ecosystem models, such as the ice-albedo feedback. Due to the challenges associated with ice internal measurements, most information about radiative transfer in sea ice has been gained by optical measurements above and below the sea ice. To improve our understanding of radiative transfer processes within the ice itself, we developed a new kind of instrument equipped with a number of multispectral light sensors that can be frozen into the ice. A first prototype consisting of a 2.3 m long chain of 48 sideward planar irradiance sensors with a vertical spacing of 0.05 m was deployed at the geographic North Pole in late August 2018, providing autonomous, vertically resolved light measurements within the ice cover during the autumn season. Here we present the first results of this instrument, discuss the advantages and application of the prototype and provide first new insights into the spatiotemporal aspect of radiative transfer within the sea ice itself. In particular, we investigate how measured attenuation coefficients relate to the optical properties of the ice pack, and show that sideward planar irradiance measurements are equivalent to measurements of total scalar irradiance.

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Attenuation of lateral propagating light in sea ice measured with an artificial lamp in winter Arctic

Cited by 8 publications

References 28 publications

The anisotropic scattering coefficient of sea ice

The anisotropic scattering coefficient of sea ice

Stable isotope evidence for the biogeochemical transformation of ancient organic matter beneath Suess Glacier, Antarctica

New insights into radiative transfer in sea ice derived from autonomous ice internal measurements

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