Abstract

Sea ice pressure ridges have been recognized as important locations for both physical and biological processes. Thus, understanding the associated light-field is crucial, but their complex structure and internal geometry render them hard to study by field methods. To calculate the in- and under-ridge light field, we combined output from an ice mechanical model with a Monte-Carlo ray tracing simulation. This results in realistic light fields showing that light levels within the ridge itself are significantly higher than under the surrounding level ice. Light guided through ridge cavities and scattering in between ridge blocks also results in a more isotropic ridge-internal light field. While the true variability of light transmittance through a ridge can only be represented in ray tracing models, we show that simple parameterizations based on ice thickness and macro-porosity allow accurate estimation of mean light levels available for photosynthesis underneath ridges in field studies and large-scale models.