Shad O'Neel, Ph.D.
Biography
Areas of Specialization and/or Research Interests
Glacier-climate interactions and sea level rise: Melting of glaciers and ice-sheets provides the largest eustatic contribution to global sea level rise. Terrestrial glaciers respond to temperature changes, but nonlinear dynamic processes at marine-terminating glaciers are important, yet poorly constrained. Such dynamic instabilities allow rapid flow and even faster iceberg calving, complicating estimates of sea level contributions.
Small glaciers: The world's glaciers and ice caps, not the great ice sheets, are changing most rapidly and will have the largest and most immediate impact on Earth's population.
Glacier-generated seismicity: Information pertaining to both flow and calving are stored in the seismograms produced by glaciers, yet these signals are poorly understood. Automatic event detection and time-series development, analysis of site and path effects, frequency-magnitude distributions are underway and serve to clarify the source physics of iceberg calving.
Photogrammetry: Dynamical information can be extracted from images acquired from spaceborne, airborne and terrestrial photography. Time-lapse sequences provide robust time series of change, and I am working on automatic processing algorithms to streamline data acquisition.
Education and/or Training
Ph.D. 2006 Institute of Arctic and Alpine Research, Dept. of Geological Sciences, University of Colorado Boulder, Geophysics
M.S. 2000 Geophysical Institute, University of Alaska Fairbanks, Geophysics
B.A. 1997 University of Montana, Environmental Geology
Professional Experience
2008 - present Research Geophysicist USGS, Alaska Science Center, Anchorage, AK
2007 - 2008 Postdoctoral Scholar, Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, UC San Diego
2007 - 2008 Geophysical Institute, University of Alaska Fairbanks
2007 Lecturer University of Colorado Boulder, graduate level glaciology
2001 - 2003 Geodetic Engineer UNAVCO in Boulder, CO; Assisted NSF research projects with GPS deployment and data processing as a Glacier GPS specialist
Professional Activities and/or Memberships
Affiliate of University of Colorado Boulder's Institute of Arctic and Alpine Research (INSTAAR)
Affiliate of Univeristy of Alaska Fairbanks, Department of Geology and Geophysics
American Geophysical Union, Cryosphere Focus Group Executive Committee
PASSCAL (Program for Array Seismic Studies of the Continental Lithosphere) Standing Committee
International Glaciological Society
Websites of Interest
http://www.usgs.gov/climate_landuse/clu_rd/glacierstudies/default.asp
http://tintin.colorado.edu/
http://fairweather.gps.alaska.edu/chris/
http://www.extremeicesurvey.org/
Featured Data Releases
McNeil, C. J., Sass, L. C., Florentine, C. E., Baker, E. H., Peitzsch, E. H., Whorton, E. N., Miller, Z. S., Fagre, D. B., Clark, A. M. and O'Neel, S. R., 2016, Glacier-Wide Mass Balance and Compiled Data Inputs: USGS Benchmark Glaciers (ver. 3.0, July 2019): U.S. Geological Survey data release, https://doi.org/10.5066/F7HD7SRF
Science and Products
Listening to Glaciers: Passive hydroacoustics near marine-terminating glaciers
The catastrophic breakup of the Larsen B Ice Shelf in the Weddell Sea in 2002 paints a vivid portrait of the effects of glacier-climate interactions. This event, along with other unexpected episodes of rapid mass loss from marine-terminating glaciers (i.e., tidewater glaciers, outlet glaciers, ice streams, ice shelves) sparked intensified study of...
Pettit, E.C.; Nystuen, J.A.; O'Neel, Shad Using surface velocities to calculate ice thickness and bed topography: A case study at Columbia Glacier, Alaska, USA
Information about glacier volume and ice thickness distribution is essential for many glaciological applications, but direct measurements of ice thickness can be difficult and costly. We present a new method that calculates ice thickness via an estimate of ice flux. We solve the familiar continuity equation between adjacent flowlines, which...
McNabb, R.W.; Hock, R.; O'Neel, Shad; Rasmussen, Lowell A.; Ahn, Y.; Braun, M.; Conway, H.; Herreid, S.; Joughin, I.; Pfeffer, W.T.; Smith, B.E.; Truffer, M. Analysis of low-frequency seismic signals generated during a multiple-iceberg calving event at Jakobshavn Isbræ, Greenland
We investigated seismic signals generated during a large-scale, multiple iceberg calving event that occurred at Jakobshavn Isbræ, Greenland, on 21 August 2009. The event was recorded by a high-rate time-lapse camera and five broadband seismic stations located within a few hundred kilometers of the terminus. During the event two full-glacier-...
Walter, Fabian; Amundson, Jason M.; O'Neel, Shad; Truffer, Martin; Fahnestock, Mark; Fricker, Helen A.
Surface Mass Balance of the Columbia Glacier, Alaska, 1978 and 2010 Balance Years
Although Columbia Glacier is one of the largest sources of glacier mass loss in Alaska, surface mass balance measurements are sparse, with only a single data set available from 1978. The dearth of surface mass-balance data prohibits partitioning of the total mass losses between dynamics and surface forcing; however, the accurate inclusion of...
O'Neel, Shad
Gulkana Glacier, Alaska-Mass balance, meteorology, and water measurements, 1997-2001
The measured winter snow, maximum winter snow, net, and annual balances for 1997-2001 in the Gulkana Glacier basin are determined at specific points and over the entire glacier area using the meteorological, hydrological, and glaciological data. We provide descriptions of glacier geometry to aid in estimation of conventional and reference surface...
March, Rod S.; O'Neel, Shad A complex relationship between calving glaciers and climate
Many terrestrial glaciers are sensitive indicators of past and present climate change as atmospheric temperature and snowfall modulate glacier volume. However, climate interpretations based on glacier behavior require careful selection of representative glaciers, as was recently pointed out for surging and debris-covered glaciers, whose behavior...
Post, A.; O'Neel, Shad; Motyka, R.J.; Streveler, G. Glacier microseismicity
We present a framework for interpreting small glacier seismic events based on data collected near the center of Bering Glacier, Alaska, in spring 2007. We find extremely high microseismicity rates (as many as tens of events per minute) occurring largely within a few kilometers of the receivers. A high-frequency class of seismicity is distinguished...
West, Michael E.; Larsen, Christopher F.; Truffer, Martin; O'Neel, Shad; LeBlanc, Laura Mapping the grounding zone of Ross Ice Shelf using ICESat laser altimetry
We use laser altimetry from the Ice, Cloud, and land Elevation Satellite (ICESat) to map the grounding zone (GZ) of the Ross Ice Shelf, Antarctica, at 491 locations where ICESat tracks cross the grounding line (GL). Ice flexure in the GZ occurs as the ice shelf responds to short-term sea-level changes due primarily to tides. ICESat repeat-track...
Brunt, Kelly M.; Fricker, Helen A.; Padman, Laurie; Scambos, Ted A.; O'Neel, Shad Iceberg calving during transition from grounded to floating ice: Columbia Glacier, Alaska
The terminus of Columbia Glacier, Alaska, unexpectedly became ungrounded in 2007 during its prolonged retreat. Visual observations showed that calving changed from a steady release of low-volume bergs, to episodic flow-perpendicular rifting, propagation, and release of very large icebergs - a style reminiscent of calving from ice shelves. Here, we...
Walter, Fabian; O'Neel, Shad; McNamara, Daniel; Pfeffer, W.T.; Bassis, Jeremy N.; Fricker, Helen Amanda Iceberg calving as a primary source of regional‐scale glacier‐generated seismicity in the St. Elias Mountains, Alaska
Since the installation of the Alaska Regional Seismic Network in the 1970s, data analysts have noted nontectonic seismic events thought to be related to glacier dynamics. While loose associations with the glaciers of the St. Elias Mountains have been made, no detailed study of the source locations has been undertaken. We performed a two-step...
O'Neel, Shad; Larsen, Christopher F.; Rupert, Natalia; Hansen, Roger Seismic detection and analysis of icequakes at Columbia Glacier, Alaska
Contributions to sea level rise from rapidly retreating marine-terminating glaciers are large and increasing. Strong increases in iceberg calving occur during retreat, which allows mass transfer to the ocean at a much higher rate than possible through surface melt alone. To study this process, we deployed an 11-sensor passive seismic network at...
O'Neel, Shad; Marshall, Hans P.; McNamara, Daniel E.; Pfeffer, William Tad Source mechanics for monochromatic icequakes produced during iceberg calving at Columbia Glacier, AK
Seismograms recorded during iceberg calving contain information pertaining to source processes during calving events. However, locally variable material properties may cause signal distortions, known as site and path effects, which must be eliminated prior to commenting on source mechanics. We applied the technique of horizontal/vertical spectral...
O'Neel, Shad; Pfeffer, W.T.