The amount of light (energy) transmitting through snow and sea ice into the ocean is still only poorly quantified and estimates are based on few observations and rough estimates. Beside its physical importance, e.g. for ice formation and melt processes, these availability of light under sea ice is crucial for biological studies and various organisms living in and under sea ice. From observations, it is known that that the distribution of light under sea ice is highly variable, but we are still lacking quantification of this variability and most relevant processes. This lack of knowledge is also due to the difficult accessibility of the under-ice environment.

Light transmittance measurements are one of our focuses in terms of sea-ice energy budgets and radiation measurements. Since 2011, we operate spectral radiometers on remotely operated vehicles (ROVs) and try to advance these measurements constantly. This advances point measurements towards horizontal transects. Temporal variability is measured through stationary setups in cooperation with international partners.

In addition to optical measurements, temperature profiles through sea ice from thermistor string (mass balance) buoys contribute to sea ice energy budgets and heat fluxes at the ice-ocean interface.