Airborne geophysical investigation targets basal boundary conditions for the Institute and Moller ice streams, West Antarctica

Lead Research Organisation: NERC British Antarctic Survey
Department Name: Science Programmes

Abstract

The Institute and Möller ice streams (IIS/MIS) drain about 20% of the West Antarctic Ice Sheet (WAIS) to the Ronne Ice Shelf, yet our knowledge of their current form and flow history is severely restricted compared with other fast flowing regions in West Antarctica. Data relating to the ice thickness and the ice-sheet bed is limited to reconnaissance transects acquired in the 1970s. Bingham and Siegert (2007) inspected these data, and showed the remarkably smooth and flat bed was similar to the Siple Coast ice streams that drain to the Ross Ice Shelf. As the Siple Coast region is thought to be underlain by marine sediments, deposited when the ice sheet size was smaller than today, Bingham and Siegert (2007) concluded a similar, probably simultaneous, history for the Institute/Möller region. The implications of this finding are significant for future changes in West Antarctica. Bingham and Siegert's (2007) analysis allows us to hypothesise substantial former ice-shelf loss and grounding line retreat in two of the three major drainage outlets of West Antarctica. An extensive airborne geophysical survey of the Institute and Möller ice streams is therefore clearly warranted, to test this hypothesis and better understand the risk of future change. The survey will also allow a better depiction of bed topography and geological boundary conditions in West Antarctica, which will allow us to better quantify the flow and form of the entire WAIS through numerical modelling. The project's objectives are as follows. 1. To undertake an airborne geophysical survey of the Institute and Möller ice streams of West Antarctica. 2. To quantify bed topography and measure bed roughness from radar data. 3. To map englacial structures (layering and crevasses). 4. To determine power reflection coefficients, forming an appreciation of basal water distribution. 5. To analyse magnetic and gravity anomalies to derive geological boundary conditions for ice flow. 6. To employ numerical modelling to quantify modern and ancient ice flow processes. 7. To use numerical modelling to predict the risk of former changes reoccurring. This project will result in the following deliverables: 1. The quantification of subglacial topography (and bed roughness) in a hitherto poorly known region of West Antarctica. This information will be made available to the BEDMAP II database, and will make a fundamental contribution as an ice sheet modelling boundary condition. We will analyse these data to determine landscape evolution and ice sheet history. 2. The classification of subglacial thermal conditions and locations of subglacial lakes. This will allow us to comprehend how ice stream flow and subglacial lake/hydrology evolution is both interrelated and affected by subglacial geology and thermal conditions. 3. The measurement of the englacial structure in the WAIS. We will analyse this information to calculate the flow history of the ice sheet and to delineate the margins of the IIS and MIS both now and in the recent past. 4. The definition of crustal structure and subglacial geology of the IIS and MIS catchments of the WAIS. The glacial history of the WAIS is of direct relevance to assessments of the present day risk of collapse and sea level rise. We aim to report our results directly to the international scientific community by linking to the Scientific Committee on Antarctic Research's (SCAR) scientific research programme entitled Antarctic Climate Evolution (ACE), which integrates geology and geophy sical datasets, forming hypotheses concerning past changes, which can be tested through modelling. The ACE link also allows us to disseminate results to the IPCC through SCAR's observer status in that organisation. We will also make results available to the SCAR programme named Subglacial Antarctic Lake Environments (SALE) and will contribute the new magnetic dataset to the international Antarctic Digital Magnetic Anomaly Project.

Publications

10 25 50

 
Description There were several significant findings that emerged from this research.

Firstly, the discovery of deep marine basins at the margin of the Weddell Sea sector of the Antarctic ice sheet that may make it more susceptible and vulnerable to change than previously suspected. Recent models predict that ocean warming could trigger more widespread instability at the end of this century. Being able to provide modellers with new subglacial topography as we did is important to reduce uncertainties in predictions of future ice sheet responses to ocean and climate warming.

The second significant discovery was new evidence for channelized subglacial water systems at the margin of the West Antarctic ice sheet. These systems are still poorly understood but their discovery spurred further attention on the role of subglacial hydrology in ice sheet dynamics.

The third discovery relates to new understanding of the evolution of the subglacial landscape in the Ellsworth Mountains an important seeding point for West Antarctic Ice Sheet development. These topographically high areas have received little attention due to the fact that they are not areas of current change but they contain important records to comprehend the longer term evolution of the ice sheet.

Another major finding came from analysing magnetic and gravity anomalies that helped unveil the geology hidden beneath the ice sheet. Investigations into the subglacial geology of the region were outdated as these were conducted in the 80's. Our more modern data led to the identification of several previously unknown features, including in particular a major fault system that forms part of the lithospheric scale tectonic boundary between East and West Antarctica.
Exploitation Route The new bedrock topography was provided to the BEDMAP-2 international consortium and is included in the most current state of the art compilation of the bed available for Antarctica.
Ice sheet modellers, glaciologists, geomorpholigists, geologists and geophysicists all use these products. All the data are in public domain.

The gravity data have been contributed to the latest compilation of gravity anomalies published in late Jan 2016 and forms an important contribution for the international geodesy and geophysics community.

The magnetic data are currently being integrated with data from many different nations and will be part of a new compilation planned for completion in 2017.
Sectors Education,Environment

 
Description The data have been incorporated into a new compilation of bed topography for Antarctica that in turn has been used in modelling efforts used to help reduce the uncertainties in future ice sheet behaviour and contributions to global sea level rise
First Year Of Impact 2011
Sector Environment
Impact Types Policy & public services

 
Title Airborne geophysics 
Description The airborne geophysics method used includes the acquisition of magnetic, gravity, radio echo sounding and laser scanning datasets. All the groups involved in the research had access to training in the data acquisition and processing techniques required 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact The method is relatively standard but the integration of all the systems makes the BAS platform one of the cutting edge platforms internationally 
URL https://www.bas.ac.uk/polar-operations/sites-and-facilities/facility/airborne-science-and-technology...
 
Title Geophysical Databases- AFI project 
Description New publically available databases of raw and processed airborne radar, magnetic and gravity data have been prepared and released from the Antarctic Funding Initiative 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
Impact The data were contributed to the BEDMAP-2 international compilation and the data has already been incorporated into the 2016 gravity compilation for Antarctica 
URL https://www.bas.ac.uk/project/aero-geophysical-investigation-of-institute-and-moller-ice-streams/
 
Description Collaboration between HEI and BAS geosciences 
Organisation Newcastle University
Department School of Geography, Politics and Sociology
Country United Kingdom 
Sector Academic/University 
PI Contribution This project was the first Antarctic funding airborne geophysics initiative to include such a wide range of University collaborators. It was a very successfull collaboration that led to new discoveries and significant knowledge exchange between researchers involved in geomorphology, geophysics, geology and glaciology. I played an important role together with the main PI (Prof Martin Siegert) in setting up and managing parts of the project and made contributions to all the papers that resulted from the research in particular those related to geophysical interpretations of subglacial geology
Collaborator Contribution The contributions where substantial ranging from studies in subglacial hyrdology, ice sheet modelling, geomorphology and glaciology
Impact This was a multi-disciplinary collaboration mostly in geosciences, with disciplines such as geography, geology and geophysics being the key components
Start Year 2011
 
Description Collaboration between HEI and BAS geosciences 
Organisation University of Aberdeen
Department Department of Geography and Environment
Country United Kingdom 
Sector Academic/University 
PI Contribution This project was the first Antarctic funding airborne geophysics initiative to include such a wide range of University collaborators. It was a very successfull collaboration that led to new discoveries and significant knowledge exchange between researchers involved in geomorphology, geophysics, geology and glaciology. I played an important role together with the main PI (Prof Martin Siegert) in setting up and managing parts of the project and made contributions to all the papers that resulted from the research in particular those related to geophysical interpretations of subglacial geology
Collaborator Contribution The contributions where substantial ranging from studies in subglacial hyrdology, ice sheet modelling, geomorphology and glaciology
Impact This was a multi-disciplinary collaboration mostly in geosciences, with disciplines such as geography, geology and geophysics being the key components
Start Year 2011
 
Description Collaboration between HEI and BAS geosciences 
Organisation University of Bristol
Department School of Geographical Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution This project was the first Antarctic funding airborne geophysics initiative to include such a wide range of University collaborators. It was a very successfull collaboration that led to new discoveries and significant knowledge exchange between researchers involved in geomorphology, geophysics, geology and glaciology. I played an important role together with the main PI (Prof Martin Siegert) in setting up and managing parts of the project and made contributions to all the papers that resulted from the research in particular those related to geophysical interpretations of subglacial geology
Collaborator Contribution The contributions where substantial ranging from studies in subglacial hyrdology, ice sheet modelling, geomorphology and glaciology
Impact This was a multi-disciplinary collaboration mostly in geosciences, with disciplines such as geography, geology and geophysics being the key components
Start Year 2011
 
Description Collaboration between HEI and BAS geosciences 
Organisation University of Edinburgh
Department School of Geosciences Edinburgh
Country United Kingdom 
Sector Academic/University 
PI Contribution This project was the first Antarctic funding airborne geophysics initiative to include such a wide range of University collaborators. It was a very successfull collaboration that led to new discoveries and significant knowledge exchange between researchers involved in geomorphology, geophysics, geology and glaciology. I played an important role together with the main PI (Prof Martin Siegert) in setting up and managing parts of the project and made contributions to all the papers that resulted from the research in particular those related to geophysical interpretations of subglacial geology
Collaborator Contribution The contributions where substantial ranging from studies in subglacial hyrdology, ice sheet modelling, geomorphology and glaciology
Impact This was a multi-disciplinary collaboration mostly in geosciences, with disciplines such as geography, geology and geophysics being the key components
Start Year 2011
 
Description Collaboration between HEI and BAS geosciences 
Organisation University of Hull
Department Department of Geography, Environment and Earth Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution This project was the first Antarctic funding airborne geophysics initiative to include such a wide range of University collaborators. It was a very successfull collaboration that led to new discoveries and significant knowledge exchange between researchers involved in geomorphology, geophysics, geology and glaciology. I played an important role together with the main PI (Prof Martin Siegert) in setting up and managing parts of the project and made contributions to all the papers that resulted from the research in particular those related to geophysical interpretations of subglacial geology
Collaborator Contribution The contributions where substantial ranging from studies in subglacial hyrdology, ice sheet modelling, geomorphology and glaciology
Impact This was a multi-disciplinary collaboration mostly in geosciences, with disciplines such as geography, geology and geophysics being the key components
Start Year 2011
 
Description Collaboration between HEI and BAS geosciences 
Organisation University of York
Country United Kingdom 
Sector Academic/University 
PI Contribution This project was the first Antarctic funding airborne geophysics initiative to include such a wide range of University collaborators. It was a very successfull collaboration that led to new discoveries and significant knowledge exchange between researchers involved in geomorphology, geophysics, geology and glaciology. I played an important role together with the main PI (Prof Martin Siegert) in setting up and managing parts of the project and made contributions to all the papers that resulted from the research in particular those related to geophysical interpretations of subglacial geology
Collaborator Contribution The contributions where substantial ranging from studies in subglacial hyrdology, ice sheet modelling, geomorphology and glaciology
Impact This was a multi-disciplinary collaboration mostly in geosciences, with disciplines such as geography, geology and geophysics being the key components
Start Year 2011