Early this season Davis saw an influx of 12 sea ice researchers/engineers here to study various aspects of the near-shore fast ice, as supported by four complementary science projects. Land-fast sea ice is a pre-eminent feature of the near-shore zone, — it is a sensitive indicator and modulator of Antarctic climate processes, and is a structuring component of Antarctic marine ecosystems. Our projects is focussed on characterizing the fast-ice, snow and ocean characteristics before and during the spring transition and to link these to changes in the fast-ice associated algal biomass.
After a delayed arrival the team was quickly deployed thanks to favourable weather, speedy access to science cargo and early sea-ice training. First data of the snow cover was collected on the day of arrival at the Davis fast-ice edge and the full deployment of the various projects followed on the fourth day after the RV Aurora Australis arrived in the harbour. Since then, we had various sampling rounds, which vary from programme to programme, for example three day cycles for the sea ice trace-metal biogeochemical team, four day cycles for the fast-ice physics and ecosystems folks, and include about two full days on the fast ice to be followed by laboratory analysis of the samples. Weather and some broken gear have slowed some work but, with the support of an incredibly skilled and enthusiastic station support team, most of our work has moved on well.
Overall the fast-ice physics and ecosystems team (five scientists, a.k.a. boffins, support by one engineer) has worked on four transects. At each of these a remotely operated vehicle (ROV; equipped with a radiometer, cameras and upward looking sonar to detect ice draft) flew in the ocean underneath the fast ice along a 128 m transect as well as covering a 32 m by 32 m box, coincident snow-thickness and ice-surface temperature measurements were taken along the transect before a second radiometer was deployed directly underneath the ice through a core hole. In addition up to 12 ice samples were taken along the transect to determine the algal biomass within the fast ice. Detailed examination of the snow cover were obtained in dedicated snow pits at 0 m, 128 m and 512 m along the transect. At the same locations three ice cores were retrieved to derive vertical profiles of ice temperatures, salinity, density, structure and isotope composition. Detailed analysis of snow, ice and water samples were then undertaken back in the science laboratory or sea-ice freezer laboratory (at −22 Celsius). Some samples will be send to Australia for further analysis. Intensive snow-thickness measurements over the wider area, which are referenced to the ice surface by internal GPS, complement the survey.
As part of an over-winter project (ably handled by the wintering science engineer and supported by the wintering team) a pair of sea-ice mass-balance stations have been recording vertical profiles of ice and snow temperatures (at two centimetre intervals) as well as the near-surface ocean and atmosphere. To key these observations in with seasonal changes in the oceanic mixed layer, vertical profiles of the ocean properties were collected at the transect site as well as next to the over-winter ice mass-balance site.
Remembering that the activities described above form only a component of the overall sea-ice research carried out off Davis station during austral spring 2015 and that there are a number of other research projects going on this spring and summer, it is easy to imagine how busy the station has been supporting us in addition to their regular maintenance and infrastructure workload. Thanks for having us at Davis.
Measuring algae in the fast ice: research blog