24 November
We have been working on the ice for more than a week now. After the arrival of our remaining team members we have been busy unpacking our gear, setting up the laboratories and establishing our field-site on the ice. We pitched a mobile work shelter (a large tent on a sled), and with a lot of help from the station, drilled a big hole for our Remotely Operated Vehicle (ROV).
We have been lucky with the weather and have completed two integrated physical-biology transects, each taking 3–4 days of work.
On day 1 we deployed our instrumented ROV to measure ice thickness and the light field under the ice using an upward-looking echo-sounder and a light sensor (radiometer) that measures the spectral distribution of the light transmitted through the sea ice and the overlying snow.
To locate and navigate the ROV we deployed an array of under-ice acoustic pingers, which are linked to GPS units at the sea-ice surface. This allows us to link under-ice and surface measurements.
On day 2 we revisited the ROV ‘transect’ (study site), collected ice cores and took measurements of ice and snow thickness. Petra has been using her new snow probe for snow thickness measurements, and Pat and Rob have been taking ice cores to measure sea-ice physical properties, including ice crystal structure, salinity and density.
To calibrate the ROV-mounted radiometer, Pat and I have been taking point measurements of under-ice light spectra and ice algal biomass along the transect. This involves using a laptop on the ice, which is tricky in cold and windy conditions as the screen freezes up and there is a lot of glare from the sun. We used an esky to keep the computer warm and a towel over our heads to read the screen.
We spent day 3 in our freezer lab and laboratories to analyse the samples. Our first results indicate that the ice algal biomass distribution is strongly influenced by snow cover, which varies from a few centimetres to about half a metre in thickness.
Lots of snow results in less light in the bottom layers of the ice and thus less algae, which need light for photosynthesis and growth. Often we can see high algal biomass in ice cores with the naked eye, as the bottom of the cores are discoloured green-brown by the algal photosynthetic pigments.
After completing the second round of ice sampling yesterday we had to pull in all our gear due to a blizzard warning. Today we have a storm of around 40 knots gusting up to 60–70 knots. While I am writing this blog, I can hear the wind howling over our accommodation building. We hope the storm is over in two days and we can then set-up our camp on the ice again.
Klaus Meiners — Chief Investigator
