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.