AFIN - Antarctic Fast Ice Network
Sea ice research in both hemispheres is extremely challenging and requires large logistical and financial efforts of all contributing partners. At the same time manifold data sets are required not only for observational studies, but in particular also to develop and finally validate numerical studies and remote sensing data products. Therefore, international collaboration is not only beneficial in terms of gathering a broad range of expertise, but also to share costs, responsibilities, and to obtain more comprehensive, wide-spread, and higher temporal resolution observations.
We are contributing to various observational programs and networks, with mostly international partners. In addition, national investment programs, as FRAM or ACROSS, are essential to fund these programs, because they often require instrumentation and logistics, which could not be afforded from purely scientific projects.
About the Antarctic Fast Ice Network AFIN
The Antarctic Fast Ice Network (AFIN) was initiated as legacy project under the International Polar Year (IPY) to establish an international network of fast-ice monitoring stations around the Antarctic coastline. By now a number of international collaborators have signed up to this project, and many have already set up fast-ice measuring sites at or near their Antarctic bases. Data collected under AFIN include ice and snow thicknesses, freeboard, dates of fast-ice formation, and (intermittent and final) breakout.
We are contributing to AFIN with sea ice measurements in Atka Bay, close to Neumayer III wintering station since 2010. The routine measurements are performed by the wintering team from early spring until breakout in January / February. In addition to baseline sea ice thickness measurements a long a cross-bay transect, a focus are platelett ice and snow cover processes as a result of ice-shelf ocean interaction. From 2011 to 2014, the Sea Ice Mass Balance Influenced by ice Shelves (SIMBIS) project strongly contributed to our monitoring program.
About the Arctic and Antarctic buoy programs
The International Arctic Buoy Program (IABP) and the International Program for Antarctic Buoys (IPAB) coordinate the multi-national efforts to gather measurements from the remote Arctic and Antarctic Ocean. The observations span from the atmosphere through snow and sea ice into the ocean, using a wide range of platforms and sensors.
In our section, we are contributing to these networks in various ways: 1) We purchase and deploy own buoys that collect data and that are shared in the community, 2) we deploy buoys for other partners making use of the regular expeditions into the ice covered oceans with Polarstern, 3) we develop new platforms and help to improve existing systems to advance our observational capabilities, 4) we distribute and archive buoy data from various partners through meereisportal.de, and 5) we are strongly involved in the coordination of the programs and developing deployment plans.
The Seasonal Ice Zone Observing Network (SIZONEThttp://www.sizonet.org/) samples sea ice state variables, such as sea-ice thickness measured with the EM-Bird and provides the results to an integrated observation network. The project’s main scientific goal is to document changes in the rapidly evolving Seasonal Ice Zone (SIZ) in order to improve our understanding and predictions of the Arctic sea-ice cover over the course of the century. The sea ice physics group is a partner in the SIZONET project and contributes with regular sea-ice thickness measurements with helicopter and Polar-5 operating from Barrow, Alaska every spring since 2007. With the ice thickness data, we investigate the state of first year and multi-year sea ice with the overarching goal to assess changes in composition of ice types and survivability in the summer season. The sea ice thickness surveys from Barrow, Alaska are also complementing validation activities for remote sensing data products, such as from CryoSat-2, into the western Beaufort and Chukchi Sea.
Recent results from AFIN observations
Ice platelets below Weddell Sea landfast sea ice
Hoppmann et al (2015, AOG; doi: 10.3189/2015AoG69A678)
Based on our work in AFIN and the SIMBIS project, this study describes the seasonal cycle of land-fast sea ice attached to the Ekström Ice Shelf, Antarctica. It shows that the underlying platelet layer develops emerged from the ice shelf cavity as early as June. Episodic accumulations throughout winter and spring led to an average platelet-layer thickness of 4m with local maxima of up to 10 m. Subsequent thinning of the platelet layer from December onwards was associated with an inflow of warm surface water. We found that nearly half of the combined solid sea-ice and ice-platelet volume in this area is generated by heat transfer to the ocean rather than to the atmosphere. The total ice-platelet volume underlying Atka Bay fast ice was equivalent to more than one-fifth of the annual basal melt volume under the Ekström Ice Shelf.