UV radiation:

About 10 days were spent at Scott Base, checking our instrumentation and then making measurements. This was followed by a week at Tent Island. The first four days there were snowing. However the next 2 days were perfect and we were able to obtain full measurements in that time.

We used two instruments. The first was a monitor which recorded the total radiation falling onto a flat surface in three bands UV,Violet and Blue. A shadow plate allowed the separation of the direct sun and the sky light, and an auxiliary filter separated UVA from UVB. This monitor was used to determine the variation of the radiation during the complete 24 hour day at Scott Base and at Tent Island, and to monitor the maximum intensity at about noon over page break the period of the project. The radiation in comparison with Wellington is dominated by the indirect skylight. The UV shows an inverse correlation with the ozone abundances determined at Arrival Heights.

The second instrument was a polarisation spectrometer, which was used to determine the sun's spectrum directly with a resolution of 1nm, and was fitted with a 5° field of view telescope, and used to determine the intensity and polarisation of skylight around the sky. These measurements were made at both Scott Base and Tent Island. The maximum polarisation which occurs at 90° to the sun, was about 0.5, which is considerably smaller than the value in New Zealand, and indicates a strongly multiple-scattering atmosphere. This instrument was also used to measure the absorption spectrum of a chlorophyl extract from the sea ice algae, and a transmission spectrum of the algae.

Sea ice algae:

Samples of sea ice algae were collected from 2 sites, under Arrival Heights and near Tent Island. Samples were obtained using an 8 inch Finn auger to cut a 1.5m deep hole in the ice, followed by a Cipre auger to obtain a core of ice from the last 0.5m. The core was shaded from direct light during removal and a sample of algae taken for return to Scott Base. Sub samples of algae were cultured in the presence of ¹⁴C at −1.5°C under an artificial light source containing both UV and visible light at irradiances typical of under ice conditions. The visible light was maintained at approximately 5μmol/m²s, while the UV irradiance was varied from experiment to experiment over a wide range. Growth rates of the algae were estimated by measuring the uptake of ¹⁴C over time using a beta spectrometer.