The structure (temperature, salinity, density and heat capacity) and transmissivity of sea ice

The transparency of sea ice to UV radiation was measured to determine the effects of enhanced UV levels on Antarctic life. The under ice radiance is controlled by the transmission of the sea ice to UV radiation. The fraction of radiation that is transmitted through the ice at different wavelengths was measured. Optical data was also recorded from the visible part of the spectrum and the two data sets were used to separate effects of absorption by algae from the intrinsic sea ice optical behaviour. The structure of the sea ice was monitored with various physical measurements including depth dependent profiles of temperature, salinity (brine volume) and density. The thermal behaviour of sea ice was studied by deploying a thermistor array to continuously monitor the temperature at eight depths. Measurements of heat capacity and theoretical predictions were used to determine the degree of solar heating at various depths. Measurements on the structure of sea ice are of considerable importance in understanding the optical behaviour of the ice and its seasonal changes.