The SNOWLIGHT project (RiS ID 12344) — “Experimental assessment of light propagation in the snowpack” — constitutes a field-oriented research initiative devoted to improving empirical understanding of how solar radiation propagates through natural snow covers. Whereas much of the existing knowledge in this field has been derived from radiative transfer modelling, SNOWLIGHT emphasises direct experimental measurement of light penetration in the upper snowpack, aiming to reduce the discrepancy between theoretical predictions and in situ optical behaviour of snow under realistic Arctic conditions.
At its core, the project develops and employs a compact, portable optical probe designed to measure scattered light intensity at sub-centimetre resolution within the snowpack. The instrument records signals across three spectral bands—red, green, and blue—providing high-resolution vertical profiles of transmitted and diffused radiation. These measurements are carried out during targeted field campaigns in Svalbard and other Arctic environments, chosen to encompass a variety of snow types differing in grain morphology, density, layering, and impurity concentration.
The empirical data obtained are subsequently analysed in conjunction with numerical simulations based on the Snow, Ice, and Aerosol Radiative (SNICAR) model, one of the most widely used radiative transfer frameworks for snow. By systematically comparing measured and modelled attenuation coefficients, the project seeks to identify the physical parameters that exert dominant control over light propagation—specifically, the influence of grain size evolution, snow density, layering effects, and the presence of light-absorbing impurities such as dust or black carbon.
Preliminary results indicate that the attenuation of visible light within the snowpack deviates from the simple exponential decay functions commonly assumed in models. Instead, empirical profiles often exhibit inflection zones or plateau regions in the uppermost few centimetres, suggesting complex interactions between scattering, absorption, and microstructural heterogeneity. These findings underscore the sensitivity of snow optical behaviour to small-scale structural and compositional variations and highlight limitations of existing parametrizations that neglect near-surface anisotropy or layering.
From a broader scientific perspective, the project’s outcomes have significant implications for cryospheric energy-balance studies, remote-sensing validation, and snow photochemistry. Accurate quantification of light penetration governs the rate of radiative heating and melting in snow, determines the evolution of albedo, and constrains the depth at which photochemical reactions and microbial activity occur. Improved empirical understanding of light transport thus contributes to refining predictive models of snowmelt dynamics, surface energy fluxes, and the climatic feedback mechanisms associated with changing snow cover.
Supported by the Arctic Field Grant (AFG), SNOWLIGHT advances a methodological framework for coupling fine-scale optical measurements with radiative transfer theory. By establishing a physically consistent basis for extrapolating visible-band results into the ultraviolet region—where direct in situ observations remain technically challenging—it represents a crucial step toward a more comprehensive and observation-driven description of the snowpack’s radiative properties in polar and alpine environments.
Referents:
- dott. Luca Teruzzi, luca.teruzzi@unimi.it