Sea Ice Physics and Ecosystems Experiment II - an integrated study of physical and ecological sea ice processes off East Antarctica during spring

The Sea Ice Physics and Ecosystems Experiment 2 (SIPEX-2) addressed key knowledge gaps in our understanding of how a changing climate may alter physical and biological processes in the Antarctic sea ice zone. The project (September – November 2012) was the second of two major multi-disciplinary and internationally collaborative sea ice field campaigns, jointly coordinated by the Australian Antarctic Division and the Antarctic Climate and Ecosystems Cooperative Research Centre. The first, SIPEX-1, was conducted in September 2007.

50 scientists from 17 institutions and 9 countries were involved in the SIPEX-2 project, which focussed on the sea ice zone off Wilkes Land, East Antarctica. Scientists used ice coring surveys and cutting-edge research tools, including remotely-operated and autonomous underwater vehicles, drifting buoys and instrumented helicopters, to understand the dynamics of the sea ice zone. The voyage resulted in important new data sets and significantly enhanced the understanding of wave propagation into ice-covered areas, floe-scale sea ice thickness distributions, and biological and biogeochemical processes in the East Antarctic sea ice zone. Biological research conducted during the voyage highlighted the importance of ice-associated algal production for under-ice pelagic food webs. Results have been published in high-profile scientific journals and a special issue. Data have also been utilised in the validation of satellite-products and the parameterisation of sea ice processes in climate and ecosystem models. The project contributes to a better understanding and future assessments of the impacts of climate change on the seasonally ice-covered areas of the Southern Ocean.

The main focus of our work was analysis of data collected during the Australian-led Sea Ice Physics and Ecosystems Experiment II (SIPEX II) voyage carried out in spring 2012 onboard RSV Aurora Australis. This multi-disciplinary research voyage was specifically designed to address key knowledge gaps in the understanding of coupled physical-biological processes in the sea ice zone off East Antarctica. Scientists analysed large datasets which were collected using a variety of state-of-the-art platforms including instrumented aircrafts, drifting buoy arrays and underwater vehicles, in combination with classical methods like ship-based observations and ice-coring surveys. Cross-disciplinary analyses were facilitated through an international project workshop held in Hobart in March 2014. New data products have enhanced our understanding of the role of sea ice in Antarctic climate and ecosystem processes. Ongoing analyses will be used for the validation of satellite products and parameterisation of climate and ecosystem models. SIPEX II research on wave-ice interactions resulted in a step-change in our understanding of the propagation of large storm-generated waves through sea ice and will help to assess recent and predicted future changes on Antarctic sea ice.
A small team of SIPEX II researchers participated in a comparative sea ice voyage to the western Weddell Sea onboard the German icebreaker Polarstern. This team collected coincident measurements of sea ice physical and biological parameters and krill distribution under sea ice, as well as through the entire water column and at the sea floor, in combination with physiological and genetic studies to better understand the habitat utilisation of this Antarctic key species. Improved characterisation of ecological dynamics in areas with contrasting sea ice conditions is critically important to assess the impacts of changing sea ice on marine ecosystems in the Australian Antarctic Territory and on circum-Antarctic scales.

The fieldwork for the Sea Ice Physics and Ecosystems Experiment II (SIPEX II) was sucessfully completed using RSV Aurora Australis in the region of 100-120°E off East Antarctica during September – November 2012. This multi-disciplinary study was specifically designed to address major knowledge gaps in Antarctic sea ice zone processes as identified by national and international end-users. Scientists measured the physical and biological properties of sea ice on small-to-regional scales using classical methods and state-of-the-art technology including ice coring surveys, remotely-operated and autonomous underwater vehicles, drifting buoys and instrumented helicopters. Data currently being processed will enhance our understanding of the role of sea ice in Antarctic climate and ecosystem processes. These data will also be utilised for the validation of satellite-derived products and the parameterisation of sea ice processes in climate and ecosystem models.