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SCAR/CliC Antarctic Sea Ice Processes & Climate (ASPeCt)

ASPeCt is an expert group on multi-disciplinary Antarctic sea ice zone research within the Scientific Committee on Antarctic Research (SCAR) Physical Sciences program and is co-sponsored by CliC. Established in 1996, ASPeCt has the key objective of improving our understanding of the Antarctic sea ice zone through focussed and ongoing field programs, remote sensing and numerical modelling. The program is designed to complement, and contribute to, other international science programs in Antarctica as well as existing and proposed research programs within national Antarctic programs. ASPeCt also includes a component of data rescue of valuable historical sea ice zone information.

The overall aim of ASPeCt is to understand and model the role of Antarctic sea ice in the coupled atmosphere-ice-ocean system. This requires an understanding of key processes, and the determination of physical, chemical, and biological properties of the sea ice zone. These are addressed by objectives which are:

  • To establish the distribution of the basic physical properties of sea ice that are important to air-sea interaction and to biological processes within the Antarctic sea-ice zone (ice and snow cover thickness distributions; structural, chemical and thermal properties of the snow and ice; upper ocean hydrography; floe size and lead distribution). These data are required to derive forcing and validation fields for climate models and to determine factors controlling the biology and ecology of the sea ice-associated biota.
  • To understand the key sea-ice zone processes necessary for improved parameterization of these processes in coupled models.
2014 Updates from ASPeCt

ASPeCt data base progress
A data acquisition and analysis software for bridge-based observations of the nearby (within approx. 1 km radius) has been developed at the Australian Antarctic Division (AAD), Hobart, Australia. The data acquisition is aligned with the former manual log and follows WMO [1970] nomenclature. Tabulated data entry is limited to the three dominant ice types, and captures ice type and thickness, its areal coverage, floe size, topography and type and thickness of any snow cover.

Post-processing includes secondary error checks as well as generating derived parameters, including area- or time-averaged ice or snow parameters. Bulk albedo, chlorophyll estimates and meltpond coverage are derived for each ice type, but may also be integrated in time or space. Graphical presentations are included in the output options. Observations from a new voyage can be uploaded in the data center by a simple synchronization of the voyage laptop (or other device used) with the ASPeCt holdings at the data center.

Currently first in field trials of the software are underway, with the public release intended for 2015. Furthermore, in response to an ASPeCt submitted resolution passed at the 2014 SCAR Delegates meeting in Auckland, New Zealand, the SCAR president is charged to draft a letter to national representatives of Council of Managers of National Antarctic Program (COMNAP) to request that "national programmes which operate shipping in the sea-ice zone participate, where possible, in the underway sea ice data collection according to the ASPeCt protocols". This resolution at this time effectively coincides with the release of the full ASPeCt ship-based observation software. Member nations will be encouraged to contribute observations on sea-ice parameters for each of their voyages into the Southern Ocean sea-ice zone using the new data acquisition software. Parties with special interest are invited to register for access to the betaversion, and to provide feedback to the developers, both from Arctic and Antarctic voyages. Contributors to the ASPeCt data base, will in turn, have direct access to the digital ASPeCt archive of ship-based observations on polar sea ice.

The ASPeCt-Bio ice core database is being further developed (through activities of SCOR-BEPSII, Biogeochemical Exchange Processes at the Sea-Ice Interfaces) and is currently being extended to include carbonate system parameters and trace-metal parameters. Sea ice core nutrient data, both in pack ice and landfast sea ice are also being included. Some 1250 measurements from various areas off Antarctica have been collated. Preliminary analysis show that nutrient concentrations have a peak in winter with median salinity-normalized concentrations close to the concentration encountered in the upwelled circumpolar deep water. Related to this, the ASPeCTBio, paper (Meiners et al., 2012) has been well received in the community and has been used to evaluate emerging biogeochemical sea ice models (e.g., Saenz and Arrigo 2014, JGR). Ice observations collected and collated through the physical ASPeCt ice thickness database and the ASPeCt-Bio dataset are now the “go-to” observational products for quantitative sea ice research/model evaluation. As an example, ASPeCt sea ice thickness data have been used/cited in the Williams et al. 2014 paper (Nature Geoscience). Additionally, the ASPeCt visual sea icobservations and snow depth data played a key role in an intercomparison exercise for satellite passive microwave algorithms done by the Integrated Climate Data
Center (ICDC) (Beitsch et al., 2015, Kern et al., 2014). WCRP/SCAR International Programme for Antarctic Buoys maintain a network of drifting buoys in the Southern Ocean. IPAB works in close collaboration with ASPeCt in particular over sea ice. More than 50 buoys were deployed during AWI Polarstern cruises in Weddell Sea, June - Aug 2013 and Jan-Mar 2014. Buoys of various types (Surface Velocity Program (SVP), Ice Mass Balance (IMB), snow, Automatic Weather Stations (AWS)) contributed by the following institutions: AWI, AAD/ACECRC, FMI, WHOI. Ten SVPs were deployed by the US Interagency Program for Antarctic Buoys (USIPAB) during the Networked Profiling Buoy (NPB) cruise in Feb 2014, in Ross Sea sector between 140° and 150° W, 55° and 65° S.

ASPeCt Workshop
ASPeCt held a Workshop at the International Glaciological Society (IGS) meeting, Hobart, Tasmania, March 2014 – joint with the Arctic Sea Ice Working group in the morning (41 members attending) and ASPeCt alone (29 members attending) in the afternoon. The goals of the workshop were two-fold; one, to bring together the two groups focused on sea ice processes to coordinate ideas and activities, and two, to discuss ASPeCt only plans. The morning session was devoted to discussion of issues of concern to both groups. The major issue discussed was the standardization of observations, such as ice cores, with the aim of forming unified approaches for sea ice observing, archiving and dissemination. This session ended with an extended discussion on ways in which Arctic and Antarctic linkages could be strengthened and a formal review of Arctic-Antarctic linkages was discussed. The afternoon session focused on a discussion of ASPeCt input to SOOS initiatives via sustained observations. Regional initiatives associated with SOOS in Prydz Bay and Amundsen and Weddell seas were discussed. Software improvements to ASPeCt observations and the use of digital photos and other automated observations from vessels to supplement visual observations were proposed. This was followed by an exhaustive discussion of the sea ice questions that the SCAR Horizon Scan was expected to review. Rob Massom coordinated the introduction of the outcomes of this discussion into the SCAR Horizon Scan. The success of this exercise was made clear in Kennicutt et al. (2014a,b) which defined six priorities for Antarctic Science and stated “What factors control Antarctic sea-ice seasonality, distribution and volume? We need to know.”

Plans of ASPeCt for 2015 and beyond

ASPeCt’s Near Future Plans include:

  • ASPeCt data collection & testing of software prototype by the AAD, AWI and CHINARE.
  • Additions to the ship observations database (ASPeCt observations) on a continuing basis.
  • Development of the ASPeCt ship-based observation system and database for sea ice measurements taken by remote vessels (airborne and under ice), shipbased instruments and surface-based instruments and sampling.
  • Planning and participation in the Antarctic Sea Ice Workshop, organized under the auspices of the Polar Research Board and tentatively scheduled for 2015. This workshop will address our current understanding of processes driving Antarctic sea ice changes, whether or not these changes remain within the expected range of natural climate variability, and why climate models continue to fail at simulating observed Antarctic sea ice changes.
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Co-Chairs are Marilyn Raphael and Steve Ackley. Learn more about this group by visiting their webpage.