English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. We describe and validate a Monte Carlo model to trackphotons over the full range of solar wavelengths as they travel intooptically thick Antarctic blue ice. The model considers both reflection andtransmission of radiation at the surface of blue ice, scattering by airbubbles within it, and spectral absorption due to the ice. The ice surface is treated as planar whilst bubbles are considered to be spherical scatteringcentres using the Henyey–Greenstein approximation. Using bubble radii andnumber concentrations that are representative of Antarctic blue ice, wecalculate spectral albedos and spectrally integrated downwelling andupwelling radiative fluxes as functions of depth and find that, relative tothe incident irradiance, there is a marked subsurface enhancement in thedownwelling flux and accordingly also in the mean irradiance. This is due to the interaction between the refractive air–ice interface and the scattering interior and is particularly notable at blue and UV wavelengths which correspond to the minimum of the absorption spectrum of ice. In contrast the absorption path length at IR wavelengths is short and consequently the attenuation is more complex than can be described by a simple Lambert–Beer style exponential decay law – instead we present a triple-exponential fit to the net irradiance against depth. We find that there is a moderate dependence on the solar zenith angle and surface conditions such as altitude and cloud optical depth. Representative broadband albedos for blue ice are calculated in the range from 0.585 to 0.621. For macroscopic absorbing inclusions we observe both geometry- and size-dependent self-shadowing that reduces thefractional irradiance incident on an inclusionu0027s surface. Despite this, theinclusions act as local photon sinks and are subject to fluxes that areseveral times the magnitude of the single-scattering contribution. Suchenhancement may have consequences for the energy budget in regions of thecryosphere where particulates are present near the surface. These resultsalso have particular relevance to measurements of the internal radiationfield: account must be taken of both self-shadowing and the optical effectof introducing the detector. Turning to the particular example of englacialmeteorites, our modelling predicts iron meteorites to reside at much reduceddepths than previously suggested in the literature (   10 cm vs. ∼  40 cm) and further shows a size dependency that may explainthe observed bias in their Antarctic size distribution.

Solar radiative transfer in Antarctic blue ice: spectral considerations, subsurface enhancement, inclusions, and meteorites