The Antarctic spring of 2012 will see the culmination of years of preparation for the ACE CRC sea-ice group, who will lead an international multi-disciplinary sea ice voyage to East Antarctica. More than 50 scientists, from 14 institutions and seven countries, are scheduled to leave on September 16 aboard the Australian research and supply vessel Aurora Australis. They will conduct the Sea Ice Physics and Ecosystem eXperiment (SIPEX-2), a seven-week voyage into the sea-ice zone to be jointly coordinated by ACE CRC and the Australian Antarctic Division. Research will be conducted at about 100-120° East, the region off Law Dome and to the east of Australia’s Casey Station. Work will begin at the sea-ice edge and the aim will be to penetrate the pack ice towards the coastal land-fast sea ice. The purpose of SIPEX-2 is to investigate relationships between the physical sea-ice environment, marine biogeochemistry and the structure of Southern Ocean ecosystems. While the scientists and crew will not set foot on terra firma, about 10 multi-day research stations will be set up on suitable sea ice floes. Scientists will use an instrumented helicopter (including high-resolution aerial photography, scanning LiDAR and microwave radiometer) to determine snow and ice thickness over regional scales. They will also measure sea-ice motion and deformation to understand the effect of ocean currents and wind on sea ice. ACE CRC bio-geochemists and ecologists are working towards a better understanding of the highly complex relationships between sea ice and snow cover physical properties, nutrients and the productivity of the sea-ice zone. Microscopic algae associated with sea ice are an important food source for Antarctic krill, a key species in Southern Ocean food web and important food source for penguins, seals and whales. The Antarctic sea-ice zone is an important driver and indicator of global climate processes - its annual freezing and melting is considered to be one of the largest seasonal cycles on Earth. Between September and November sea ice cover will be at its maximum annual extent. ACE CRC/AAD sea-ice ecologist Dr Klaus Meiners (pictured above) is the chief scientist of the project. “We aim to achieve from this voyage an expansion of the multi-disciplinary observational record of East Antarctic sea ice characteristics and processes and an assessment of impacts of climate change on the physical and biological elements of the Antarctic sea ice zone,” he said. “We will measure a large number of environmental and ecological parameters across different sea ice regimes to understand the physical processes and their impact on the ecosystem of the Southern Ocean. Data collected during the voyage will be used to improve satellite estimates of sea-ice thickness, provide input to sea-ice physical and ecosystem models and will help to detect climate change impacts in the Southern Ocean.” One of the key players on the trip is not a scientist but an Autonomous Underwater Vehicle, which will be operated in partnership with the Woods Hole Oceanographic Institution in the United States. The AUV, fitted with an upward-looking sonar, will measure the draft of sea ice floes. These measurements will be complemented by airborne sea-ice surface elevation and in-situ ice coring surveys to improve estimates of ice thickness and total sea-ice volume. Its partner in science will be a Remotely Operated Vehicle (ROV), which will be driven very close to the subsurface of the ice to measure optical properties to estimate the amount of ice algae as well as filming the under-ice krill population. This will help scientists to understand the relationships between sea ice, ice algae and krill. More sub-ice samples will be collected by suction pumps and nets and will be used for physiological experiments with krill. This project is a continuation and extension of the first SIPEX voyage, which took place in September/October 2007 and resulted in the publication of a Special Volume on Antarctic sea ice, containing 25 original publications, in the journal Deep-Sea Research II.

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