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Airborne Geophysical Survey of the Amundsen Embayment

Principal Investigators: J.W. Holt, D.L. Morse, and D.D. Blankenship, The University of Texas at Austin
Funded by: National Science Foundation - award # 0230197


Ice Thickness and Subglacial Topography Results
from the joint UTIG-BAS campaign of 2004-05 are now available HERE!

The Ross Sea and Weddell Sea embayments have been the primary focus of attention within the West Antarctic Ice Sheet (WAIS) since the potential for ice sheet collapse and its resulting impact on sea level was first recognized. The third major drainage basin of the WAIS, the Amundsen Sea Embayment (ASE), has been comparatively unstudied primarily due to its remoteness from logistical centers. However, satellite remote sensing studies, combined with limited ice thickness data, indicate that the ASE discharges the largest ice flux in West Antarctica; furthermore, of all the major drainage basins in Antarctica, it is the only one to exhibit significant elevation change over the period of recent satellite observations.

Our present knowledge of the ice thickness and subglacial boundary conditions in the ASE are insufficient to understand its evolution or sensitivity to climatic change. Stimulated by observations of its non-steady behavior and its dominant role in WAIS net mass balance, the glaciers of the ASE have become a focus for future integrated studies by both the U.S. and European scientific communities with the overarching objectives of assessing the present and predicting the future behavior of the ice sheet in the ASE. Through a series of meetings held by the WAIS science community, an ASE Science Plan has been generated to achieve these objectives through coordinated satellite, airborne, marine and surface-based observations.

Context maps of West Amtarctica showing it's three major ice drainages: the Amundsen Sea Embayment, the Ross Sea Embayment, and Weddell Sea Embayment
Context maps of West Antarctica showing its three major ice drainages: the Amundsen Sea Embayment (ASE), the Ross Sea Embayment (RSE) and Weddell Sea Embayment (WSE). The balance velocity map (a) gives an estimate of the ice flow required to maintan the modern surface topography given the modern accumulation rate (from Babmer, 2000). The outlines of drainage basins feeding Pine Island Glcaier (PIG) and Thwaites Glacier (TG) are shown in yellow. (b) BEDMAP bedrock topography (Lythe et al., 2000) showing elevations below -1000 m in yellow (e.g. the Bryd Subglacial Basin - BSB), and elevations above 1000 m in violet. Major crustal blocks Marie Byrd Land (MBL), Thurston Island (TI), Antarctic Peninsula (AP), Ellsworth-Whitmore Mountains (EWB) and Transantarctic Mountains (TAM) are defined by their bed relief. Hypothesized flanks of the West Antarctic Rift System (WARS) are shown in white.

In order to accomplish the airborne phase of this plan, The University of Texas (UT) and the British Antarctic Survey (BAS) have been funded to conduct a comprehensive aerogeophysical survey encompassing the two major drainage basins within the Amundsen Sea Embayment - Pine Island and Thwaites glaciers. We will conduct these surveys during the 2004/05 austral summer, operating from two remote field camps and using two survey aircraft. In response to logistical constraints, we have revised the survey plan from our original proposal on order to accomplish these surveys in a single field season, rather than in two. Additionally, the recent CECS/NASA reconnaissance/survey flights in the ASE have provided new insights to the dynamics of the grounding line regions. Over the coming year, we as a community have the opportunity to optimize the survey design and refine our detailed target priorities in order to best achieve the objectives of the Science and Implementation Plan as the evolving logistical constraints. Geophysical maps resulting from these surveys will be central to achieving fundamental objectives of the ASE Science Plan and will guide future surface-based research. Providing these geophysical results to the ASE science community is our primary objective.