Proposed Experiment Design:

For our original proposal, we developed a plan to survey the roughly triangular region shown above (with sides of 800 x 800 x 1100 km) in two field seasons. BAS and UTIG would each field an airborne platform with laser (UTIG only), radar sounder, gravity and magnetic instrumentation. The US and UK aircraft would complete the PIB survey in the 2003/04 season; and UTIG would survey in both the PIB and TGB regions in 2003/04 and will be solely responsible to complete the TGB survey during the 2005/06 season. Given the range of Twin Otter aircraft, a camp located in the drainage basin located between Thwaites Glacier and Pine Island Glacier basins (DBA) would be required for the PIB survey (and portions of the TGB), while for most of the TGB survey, a base of operations located on the ice divide separating the drainage basins for the Ross and Amundsen Seas (RAD) would be most suitable.

Coverage of proposed ASE aerogeophysical survey shown superimposed on (a) balance velocity and surface elevations contours, (b) bed topography, and (c) existing data coverage. We have subdivided the survey into two sections: Pine Island Glacier basin (PIB) block to be surveyed from a field camp within “Drainage Basin A” (DBA) and Thwaites Glacier basin (TGB) block to be surveyed from the Ross - Amundsen flow divide (RAD).

With these aerogeophysical and logistical resources, we planned to survey the entire Thwaites Glacier Basin (TGB) at 7.5 x 15 km (53,000 line km) and the more remote Pine Island Basin (PIB) at 15 x 15 km (34,000 line km).  The 7.5 km spacing was oriented to maximize coverage of along-flow profiles and optimize along-flow sampling of ice dynamics features (e.g., tributaries, glacier trunks and grounding zones). In addition, this coverage would well sample potential field anomalies with sources at or near the base of the ice (e.g., subglacial volcanics); coverage for anomalies with deeper sources (e.g., major crustal boundaries and tectonically controlled sedimentary basins) would be excellent. The planned 15 x 15 km PIB survey grid (34,000 line km) was a compromise that recognizes the logistical difficulties of operating within the PIB (e.g., weather and increased distance from McMurdo). Even with these limitations, this grid spacing was still suitable for mapping crustal boundaries (e.g., TI-EWB relationship), larger sedimentary basins (e.g., BSB axis) and along flow transitions in ice dynamics (e.g., tributary and trunk onset as well as grounding lines).

Actual Experiment Design:

However, NSF decided they could only support a single field season, so this meant either a drastic reduction in the area of the survey or coarser grid spacing.  The latter was chosen due to the ASE science community's need for catchment-wide information.  Pine Island catchment therefore became a roughly 30 x 30 km grid spacing, while Thwaites was planned for 15 x 15 km with the knowledge that it was unlikely to get that spacing over the full area.  (Hey, if you don't aim for the stars you'll never reach them.)  The two teams and two aircraft deployed for the 2004/05 season and attempted to survey as much as possible.  BAS was based at Pine Island Camp, and UTIG was based at Thwaites Camp.  UTIG also used Pine Island Camp as a secondary base. 

ASE survey area shown in grey, with all other UTIG aerogeophysical surveys shown for scale. Colored regions were flown with regular grids, individual flight track are shown (in red) for line oriented surveys.