Description: The Global Sea-level Observing System (GLOSS) was established by the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 1985 to provide oversight and coordination for global and regional sea-level networks in support of scien- tific research. The first GLOSS Implementation Plan (GIP) in 1990 established the GLOSS Core Network (GCN) of ~300 tide gauges distributed around the world, technical standards for GLOSS tide gauge stations, as well as the basic terms and obligations for Member States participating in GLOSS. The second GIP in 1997 expanded the GLOSS programme to include sub-networks focused on long historical records suitable for the detection of long-term sea- level trends and accelerations (GLOSS-LTT), a cali- bration network for satellite altimetry (GLOSS-ALT), and a network suitable for monitoring aspects of the global ocean circulation (GLOSS-OC). In addition, a strategy for integrating Global Positioning System (GPS) into monitoring of land levels at GLOSS tide gauges was developed. The focus of the GIP 2012 remains the GCN and the datasets that result from this network. The new plan calls for two significant upgrades to the GCN moti- vated by scientific and operational requirements: 1) all GCN stations are required to report data in near-real time, which will be tracked at a Sea-level Station Monitoring Facility. This will involve upgrades in power, data acquisition plat- forms, and communication packages; however, these upgrades are cost-effective in terms of the benefits that a real-time system will provide for ocean monitoring and improved station perfor- mance due to early detection of station malfunc- tions; 2) continuous measurements of the Global Navigation Satellite System (GNSS), in particular the U.S. Global Positioning System (GPS), the Russian GLONASS, or the newly established European GALILEO, or equivalent systems, in the vicinity of the tide gauge benchmark (TGBM) are required for all GCN stations. This upgrade will support satellite altimetry calibration and research efforts aimed at determining geocentric global sea-level rise rates as well as regional changes in sea level. Most relevant, vertical land movements can signifi- cantly alter the rates of sea-level rise expected from the sole climatic contributions of ocean ther- mal expansion and land-based ice melting, possi- bly magnifying the impacts of sea-level rise on the coast. In many cases, this requirement can be met by taking advantage of existing GNSS receivers maintained by other groups, as long as a precise geodetic tie to the GCN tide gauge can be made using, e.g. conventional levelling. The organization of the plan is as follows. An over- view of the GLOSS programme (chapter 1) and a brief summary of the uses of tide gauge data (chapter 2) are presented. The current status of the GLOSS programme is considered (chapter 3), followed by a discussion of the sea-level monitoring requirements raised by advisory groups and panels (chapter 4), as well as a self-assessment based on specific research and operational applications (chapter 5). These requirements are used to develop implementation goals for the GLOSS networks and data centres (chapter 6). Minor modifications are proposed for the administrative structure of GLOSS aimed at providing improved oversight of the imple- mentation plan (chapter 7). The success of the plan depends critically on the participation of Member States, whose obligations are summarized (chapter 8). The successful Training, Education and Mutual Assistance programmes that have been a corner stone of GLOSS will be continued to help meet implementation requirements (chapter 9). Additional technical and programmatic details are included in a set of appendices.

Description: OpenASFA input

Description: Published

Description: Refereed

Description: From data collected by RV Polarstern, and additional echosoundings provided by national hydrographic offices, research institutions and the International Hydrographic Organization (IHO) Digital Bathymetric Data Center, the 1:1,000,000 Bathymetric Chart of the Weddell Sea (AWl BCWS) series has been developed. The heterogeneity of bathymetric data and the lack of observations within ice-covered areas required the incorporation of supplementary geophysical and geographical information. A semi-automatic procedure was developed for terrain modeling and contouring. In coastal regions, adjacent sub-glacial information was included in order to model the bathymetry of the transition zone along the Antarctic ice edge. Six sheets of the AWl BCWS series in the scale of 1:1,000,000 covering the southern Weddell Sea from 66°S to 78°S and from 68°W to 0°E were recently completed and included in the 1997 GEneral Bathymetric Chart of the Oceans (GEBCO) Digital Atlas CD-ROM (http://www.gebco.net). On the basis of these six 1:1,000,000 AWl BCWS sheets, a generalized 1:3,000,000-scale bathymetric chart was compiled for the entire southern Weddell Sea.

Description: Distinct facies types, classified in radiocarbon-dated sediments from the shelf of the Lazarev Sea, East Antarctica, reveal a detailed history of processes that have controlled sedimentation during the deglaciation over the last 10,000 yr. The ice retreat on this part of the Antarctic shelf started 9500 yr BP, marked by the deposition of laminated sediments, deposited from a floating ice shelf. These laminites, which occur on top of diamictons laid down from a grounded ice sheet, are the basal sediments of the postglacial sequence. The intensity of the Antarctic Coastal Current (ACC), directed by shelf morphology, controlled sedimentation of the postglacial facies. A residual glaciomarine sediment with the fine fraction winnowed by strong currents developed from 9000-8000 yr BP in the western part of the investigation area and from 9000-5000 yr BP in the eastern part, closer to the prominent 'Fenno Deep' trough. Current velocities apparently decreased between 8000 and 2000 yr BP due to a deflection of the ACC by advancing ice tongues to the east of the investigation area during the 'Hypsithermal'. This led to a deposition of fine-grained sediments, and clay mineralogy suggests a continental source, possibly near the grounding line of the Nivl Ice Shelf, rather than a winnowing of sediments near the shelf break or advection from deeper water. Current velocities intensified after 2000 yr BP, removed fine material from these sediments and led to a relict sediment, consisting of coarse bryozoan and molluscan debris.