APL Home
APL-UW Home

Jobs
About
Campus Map
Contact
Privacy
Intranet

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

Publications

2000-present and while at APL-UW

Seasonal to multiyear variability of glacier surface velocity, terminus position, and sea ice/ice melange in northwest Greenland

Moon, T., I, Joughin, and B. Smith, "Seasonal to multiyear variability of glacier surface velocity, terminus position, and sea ice/ice melange in northwest Greenland," J. Geophys. Res., 120, 818-833, doi:10.1002/2015JF003494, 2015.

More Info

13 May 2015

Glacier ice discharge, which depends on ice velocity and terminus fluctuations, is a primary component of Greenland Ice Sheet mass loss. Some research suggests that ice melange influences terminus calving, in turn affecting glacier velocity. The details and broad spatiotemporal consistency of these relationships, however, is undetermined. Focusing on 16 northwestern Greenland glaciers during 2009 through summer 2014, we examined seasonal surface velocity changes, glacier terminus position, and sea ice and ice melange conditions. For a longer-term analysis, we also produced extended records of four glaciers from 1999 to 2014. There is a strong correspondence between seasonal near-terminus sea ice/melange conditions and terminus change, with rigid ice melange conditions associated with advance and open water associated with retreat. Extended sea ice-free periods and reduced rigid melange are also linked with anomalously large terminus retreat. In all but one case, sustained multiyear retreat of greater than 1 km during both the 15-year and 6-year records was accompanied by interannual velocity increases. Seasonal velocity patterns, however, correspond more strongly with runoff changes than terminus behavior. Projections of continued warming and longer sea ice-free periods around Greenland indicate that notable retreat over wide areas may continue. This sustained retreat likely will contribute to multiyear speedup. Longer melt seasons and earlier breakup of melange may also alter the timing of seasonal ice flow variability.

Marine ice sheet collapse potentially underway for the Thwaites Glacier Basin, West Antarctica

Joughin, I., B.E. Smith, and B. Medley, "Marine ice sheet collapse potentially underway for the Thwaites Glacier Basin, West Antarctica," Science, 344, 735-738, doi: 10.1126/science.1249055, 2014

More Info

16 May 2014

Resting atop a deep marine basin, the West Antarctic Ice Sheet has long been considered prone to instability. Using a numerical model, we investigate the sensitivity of Thwaites Glacier to ocean melt and whether unstable retreat is already underway. Our model reproduces observed losses when forced with ocean melt comparable to estimates. Simulated losses are moderate (<0.25 mm per year sea level) over the 21st Century, but generally increase thereafter. Except possibly for the lowest-melt scenario, the simulations indicate early-stage collapse has begun. Less certain is the timescale, with onset of rapid (> 1 mm per year of sea-level rise) collapse for the different simulations within the range of two to nine centuries.

Transition of flow regime along a marine-terminating outlet glacier in East Antarctica

Callens, D., K. Matsuoka, D. Steinhage, B. Smith, E. Witrant, and F. Pattyn, "Transition of flow regime along a marine-terminating outlet glacier in East Antarctica," Cryosphere, 8, 867-875, doi:10.5194/tc-8-867-2014, 2014.

More Info

13 May 2014

We present results of a multi-methodological approach to characterize the flow regime of West Ragnhild Glacier, the widest glacier in Dronning Maud Land, Antarctica. A new airborne radar survey points to substantially thicker ice (>2000 m) than previously thought. With a discharge estimate of 13%u201314 Gt yr%u22121, West Ragnhild Glacier thus becomes of the three major outlet glaciers in Dronning Maud Land. Its bed topography is distinct between the upstream and downstream section: in the downstream section (<65 km upstream of the grounding line), the glacier overlies a wide and flat basin well below the sea level, while the upstream region is more mountainous. Spectral analysis of the bed topography also reveals this clear contrast and suggests that the downstream area is sediment covered. Furthermore, bed-returned power varies by 30 dB within 20 km near the bed flatness transition, suggesting that the water content at bed/ice interface increases over a short distance downstream, hence pointing to water-rich sediment. Ice flow speed observed in the downstream part of the glacier (~250 m yr%u22121) can only be explained through very low basal friction, leading to a substantial amount of basal sliding in the downstream 65 km of the glacier. All the above lines of evidence (sediment bed, wetness and basal motion) and the relatively flat grounding zone give the potential for West Ragnhild Glacier to be more sensitive to external forcing compared to other major outlet glaciers in this region, which are more stable due to their bed geometry (e.g. Shirase Glacier).

More Publications

In The News

Hidden lakes drain below West Antarctica's Thwaites Glacier

UW News and Information, Hannah Hickey

Thwaites Glacier on the edge of West Antarctica is one of the planet’s fastest-moving glaciers. Research shows that it is sliding unstoppably into the ocean, mainly due to warmer seawater lapping at its underside.

8 Feb 2017

What Antarctica's incredible "growing" icepack really means

National Geographic, Brian Clark Howard

Are the Antarctic's ice sheets shrinking or growing? And what does that mean for global sea-level rise? Ben Smith, who was not involved with the study, notes that the technology used to collect surface elevation measurements might not be up to the task of distinguishing snowpack volume based on differences of one or two centimeters.

3 Nov 2015

Antarctica accumulates more ice than it melts

Business Insider, Rebecca Harrington

The snow that falls on Antarctica every year is accumulating as ice faster than it's melting on the continent, a new study from NASA found. Ben Smith, not involved in the study, notes that precise records of snow accumulation are needed to fully understand the nature of the net ice gains and losses.

2 Nov 2015

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
Close

 

Close