RADIO-STRATIGRAPHY OF THE GREENLAND ICE SHEET

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Objectives: Understanding the history and evolution of ice sheets in response to climate change is an area of active research, motivated by the need to improve estimates of their contribution to modern sea-level rise. The Greenland Ice Sheet (GIS), a major component of the Arctic system, is particularly vulnerable to climate change due to both its physical setting and direct ocean– atmosphere–ice interactions. Both its variability in extent across glacial–interglacial cycles and recent observations of surface-melt-induced acceleration emphasize this sensitivity. Predictive ice-sheet models are our best tools for understanding the cumulative effects of these and other processes upon the GIS. However, these models lack detailed knowledge of the GIS basal boundary condition, which is a critical control upon ice flow. They also do not take advantage of the wealth of information contained with its internal radiostratigraphy, but that will soon change and become a key component of their validation and application as predictive tools.

To address this need for new constraints on ice-sheet models, we will develop, validate, and analyze a new radiostratigraphic database of the GIS. The database will be derived from existing (e.g., PARCA, CReSIS) and ongoing (e.g., IceBridge) airborne radar-sounding campaigns. This project is collaborative across 3 US-based academic institutions; UT (Joe MacGregor - Lead PI; Catania), UAF (Mark Fahnestock) and CReSIS (Prasad Gogenini and John Paden).

Presentations and Publications:

MacGregor, M. Fahnestock, G. Catania, J. Paden, S. Gogenini, S. Young, S. Rybarski, A. Mabrey, B. Wagman, M. Morlighem, in press, Radiostratigraphy and age structure of the Greenland Ice Sheet, Journal of Geophysical Research.

J. MacGregor, M. Fahnestock, G. Catania, J. Paden, S. Gogineni, M. Morlighem, W. Colgan, J. Li, D. Stillman, R. Grimm, G. Clow, K. Young, A. Mabrey, S. Rybarski, B. Wagman, K. Rodriguez, The Greenland Ice Sheet in three dimensions, Abstract C24B-03 presented at 2014 Fall Meeting, AGU, San Francisco, CA, 15-19 Dec.

J. MacGregor, M. Fahnestock, G. Catania, J.D. Paden, S. Gogineni, S. Rybarski, K. Young, A. Mabrey, B. Wagman, Radiostratigraphy of the Greenland ice sheet, Abstract C53D-05 presented at 2013 Fall Meeting, AGU, San Francisco, CA, 9-13 Dec.

J. MacGregor, M. Fahnestock, G. Catania, J.D. Paden, B. Wagman, S. Rybarski, K. Young, A. Mabrey, Ra- diostratigraphy of the Greenland ice sheet from the 2009-2012 Operation IceBridge surveys, Abstract C12B-03 presented at 2012 Fall Meeting, AGU, San Francisco, CA, 3-7 Dec.

J. MacGregor, M. Fahnestock, G. Catania, S. Price, J. Paden, The gap between ice-penetrating radar observa- tions and the boundary conditions used in ice-sheet models, Abstract EGU2012-1033, presented at 2012 EGU General Assembly, Vienna, Austria, 22-27 April.