Ohio State University
Geological Sciences and Byrd Polar
Supporting Stations: McMurdo Station
Research Locations: West Antarctica
Phase 2 of the Antarctic-POLENET project (ANET) will continue and expand GPS and seismic studies to advance understanding of geodynamic processes and their influence on the West Antarctic Ice Sheet(WAIS). The ANET instrumentation deployed during Phase 1 will be augmented by nine new remote continuous GPS stations, to be deployed in collaboration with UK and Italian partners. In partnership with UK colleagues, a high-resolution crustal and mantle seismic array will also traverse the deep subglacial basins underlying the catchments of the glacio-dynamically critical Pine Island and Thwaites Glacier regions, where crust and mantle structure are poorly resolved. Absolute gravity data will provide important independent data on crustal uplift and mass change, helping discriminate rebound driven by modern versus ancient ice-mass change. The integrated geodetic and geophysical data will allow testing of key hypotheses about the history and dynamics of the West Antarctic Ice Sheet and interactions with the solid Earth beneath. The behavior of the polar ice sheets has immense societal impact because of their potential to affect sea level. Both the viscoelastic response of the solid earth, constraining mass change since the Last Glacial Maximum, and the elastic response, resulting from mass change within the last few decades, can be modeled from continuous GPS measurements together with earth properties derived from the seismic data. These ice mass change estimates will allow better estimates of the contribution of the Antarctic ice sheets to global sea level change.
Field Season Overview:
In the 2013-14 field season, (year 1 of Phase 2), will consist of both servicing of existing GPS/seismic stations and installation of a small number of ‘backbone’ stations at new locations. Work planned for this season will be carried out using Twin Otter support from South Pole Station, the ALE Camp at Union Glacier, and McMurdo Station. Each of the 7 seismic stations located on the ice sheet of the East Antarctic Plateau must have the lithium battery packs replaced to operate for an additional 2 years. These stations will be serviced from South Pole Station. The ALE camp at Union Glacier will be used as a hub to service 7-8 existing stations and to install 5 new GPS with 2 co-located seismic instruments at critical locations around the Weddell Embayment. To reach the most distant locations, 2 new fuel caches deployed by LC-130 airdrop are required at ‘Pillow Knob’ (site of fuel airdrops in prior seasons) and ‘June Carter Cache’. These are mission-critical and need to be timed to coincide with field team work in these regions. McMurdo Station will be the hub for servicing 7-8 existing stations (using Twin Otter and helo flight support), and installing 1 GPS station in the Transantarctic Mountains near Mt Bumstead. No campaign is planned for the Amundsen Embayment of Marie Byrd Land sectors of West Antarctic, however: a) If aircraft time and camp operations permit, a very short-duration visit to WAIS-Divide Camp would allow servicing of two key sites; and b) we hope to piggy-back on Ross Ice Shelf seismic project resources and personnel to service the Mt Patterson and Mt Sidley sites from Siple Dome. Coordinated work with the Italian Antarctic program (PNRA) is planned for northern Victoria Land. Using Italian aircraft, and working with Italian team members, 3 GPS systems will be installed at existing GPS monuments from our partner VLNDEF project. The POLENET team will need fixed-wing transport for 1-2 team members and GPS equipment to Mario Zuchelli Station and return to McMurdo Station.
Priority for site visits is: 1A) New installation, 1B) Sites that are not fully operational; Sites that have not been visited in 2 years; and sites where upgrades were not fully completed last season, and 2) Sites (fully functioning) needing minor maintenance and/or visits to acquire seismic data. We note that the number of sites in category 1B (not fully operational) is likely to change in the next 6 months, prior to commencement of the field season, and we request flexibility in our site visit plans to cover this eventuality.
The scope of absolute gravity measurements for this field season is not clearly defined at this point. Our French collaborators have decided to postpone planned measurements from Palmer Station until the 2014-15 season. Our partners at the NOAA/National Geodetic Survey may provide an A-10 and technician to make absolute gravity measurements, but only from McMurdo in the late part of the season. This part of the program is still being coordinated by Larry Hothem, USGS, and Vicki Childers, NGS.
There is a continued need for dedicated weather forecasting across an extensive portion of East and West Antarctica during our field work, as provided by OPP-SPAWAR.
Deploying Team Members:
Terry Wilson (PI)