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Benjamin Smith

Principal Physicist

Affiliate Associate Professor, Earth and Space Sciences

Email

bsmith@apl.washington.edu

Phone

206-616-9176

Department Affiliation

Polar Science Center

Education

Ph.D. Earth & Space Sciences/Geophysics, University of Washington - Seattle, 2005

M.S. Geology & Geophysics, University of Wisconsin - Madison, 1999

B.S. Physics, University of Chicago, 1997

Publications

2000-present and while at APL-UW

The Reference Elevation Model of Antarctica

Howat, I.M., C. Porter, B.E. Smith, M.-J. Noh, and P. Morin, "The Reference Elevation Model of Antarctica," Cryosphere, 13, 665-674, doi:10.5194/tc-13-665-2019, 2019.

More Info

26 Feb 2019

The Reference Elevation Model of Antarctica (REMA) is the first continental-scale digital elevation model (DEM) at a resolution of less than 10 m. REMA is created from stereophotogrammetry with submeter resolution optical, commercial satellite imagery. The higher spatial and radiometric resolutions of this imagery enable high-quality surface extraction over the low-contrast ice sheet surface. The DEMs are registered to satellite radar and laser altimetry and are mosaicked to provide a continuous surface covering nearly 95% the entire continent. The mosaic includes an error estimate and a time stamp, enabling change measurement. Typical elevation errors are less than 1 m, as validated by the comparison to airborne laser altimetry. REMA provides a powerful new resource for Antarctic science and provides a proof of concept for generating accurate high-resolution repeat topography at continental scales.

Nonlinear rise in Greenland runoff in response to post-industrial Arctic warming

Trusel, L.D., and 8 other including B.E. Smith, "Nonlinear rise in Greenland runoff in response to post-industrial Arctic warming," Nature, 564, 104-108, doi:10.1038/s41586-018-0752-4, 2018.

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5 Dec 2018

The Greenland ice sheet (GrIS) is a growing contributor to global sea-level rise, with recent ice mass loss dominated by surface meltwater runoff. Satellite observations reveal positive trends in GrIS surface melt extent, but melt variability, intensity and runoff remain uncertain before the satellite era. Here we present the first continuous, multi-century and observationally constrained record of GrIS surface melt intensity and runoff, revealing that the magnitude of recent GrIS melting is exceptional over at least the last 350 years. We develop this record through stratigraphic analysis of central west Greenland ice cores, and demonstrate that measurements of refrozen melt layers in percolation zone ice cores can be used to quantifiably, and reproducibly, reconstruct past melt rates. We show significant (P < 0.01) and spatially extensive correlations between these ice-core-derived melt records and modelled melt rates and satellite-derived melt duration across Greenland more broadly, enabling the reconstruction of past ice-sheet-scale surface melt intensity and runoff. We find that the initiation of increases in GrIS melting closely follow the onset of industrial-era Arctic warming in the mid-1800s, but that the magnitude of GrIS melting has only recently emerged beyond the range of natural variability. Owing to a nonlinear response of surface melting to increasing summer air temperatures, continued atmospheric warming will lead to rapid increases in GrIS runoff and sea-level contributions.

Greenland Ice Mapping Project: Ice flow velocity variation at sub-monthly to decadal timescales

Joughin, I., B.E. Smith, and I. Howat, "Greenland Ice Mapping Project: Ice flow velocity variation at sub-monthly to decadal timescales," Cryosphere, 12, 2211-2227, doi:10.5194/tc-12-2211-2018, 2018.

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11 Jul 2018

We describe several new ice velocity maps produced by the Greenland Ice Mapping Project (GIMP) using Landsat 8 and Copernicus Sentinel 1A/B data. We then focus on several sites where we analyse these data in conjunction with earlier data from this project, which extend back to the year 2000. At Jakobshavn Isbræ and Køge Bugt, we find good agreement when comparing results from different sensors. In a change from recent behaviour, Jakobshavn Isbræ began slowing substantially in 2017, with a midsummer peak that was even slower than some previous winter minima. Over the last decade, we identify two major slowdown events at Køge Bugt that coincide with short-term advances of the terminus. We also examined populations of glaciers in north-west and south-west Greenland to produce a record of speed-up since 2000. Collectively these glaciers continue to speed up, but there are regional differences in the timing of periods of peak speed-up. In addition, we computed trends in winter flow speed for much of the south-west margin of the ice sheet and find little in the way of statistically significant changes over the period covered by our data. Finally, although the consistency of the data is generally good over time and across sensors, our analysis indicates that substantial differences can arise in regions with high strain rates (e.g. shear margins) where sensor resolution can become a factor. For applications such as constraining model inversions, users should factor in the impact that the data's resolution has on their results.

More Publications

In The News

Key data for NASA's ice-monitoring satellite in trouble thanks to shutdown

Gizmodo, Maddie Stone

the spring campaign for NASA’s Operation IceBridge — a series of airborne flights over the Arctic and Antarctic the space agency has been conducting since 2009 — would likely be delayed thanks to President Trump’s fictitious crisis at the U.S. southern border.

23 Jan 2019

Shutdown imperils NASA's decadelong ice-measuring campaign

Science, Paul Voosen

The partial U.S. government shutdown threaten to shorten IceBridge missions, a decadelong NASA aerial campaign meant to secure a seamless record of ice loss. Ben Smith comments that this will imperil the plan to collect overlapping data with the new ice-monitoring satellite called the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2).

18 Jan 2019

UW glaciologist gets first look at NASA's new measurements of ice sheet elevation

UW News, Hannah Hickey

Less than three months into its mission, NASA's Ice, Cloud and land Elevation Satellite-2, or ICESat-2, is already exceeding scientists’ expectations. Benjamin Smith, a member of the ICESat-2 science team, shared the first look at the satellite's performance at the American Geophysical Union's annual meeting Dec. 11 in Washington, D.C.

14 Dec 2018

More News Items

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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