Fax: 206-543-0489 (shared)
Interests: Glacier dynamics and histories of glaciers and ice sheets, Snow avalanche dynamics
Research Groups: Glaciology
My research focuses on observing and modeling physical processes in the cryosphere. In particular, I study the behavior of snow and ice masses and their impacts on society and their response to the changing environment. My research is interdisciplinary. On-going research includes:
I. Flow history and stabilty of the Antarctic Ice Sheet
Recent measurements show that parts of the West Antarctic ice sheet are now undergoing rapid and dramatic change, but it is not clear whether the changes are manifestations of natural short-term variability or impending collapse. Our ongoing studies use geophysical measurements and models to infer the flow history of the ice sheet. Some of our studies include:
- during 1997-98 we completed a series of ice-penetrating radar traverses across Roosevelt Island in the Eastern Ross Sea; the measurements were used in a transient ice-flow model, which enabled us to place constraints on Holocene deglaciation of the West Antarctic Ice Sheet;
- from 2000 to 2003 we carried out meaurements of ice thickness and internal stratigraphy using ice-penetrating radar and measurements of surface velocity using GPS methods in order to investigate the flow history of the Ross Ice Streams;
- emerging observations and measurements indicate rapid changes in the speed of fast-flowing outlet glaciers and ice streams can occur over short timescales (months to years). As a part of this project, we developed a full-stress ice-flow model to investigate inland migration of fast-flowing glaciers and ice streams
- geophysical observations and models to determine the site for a new, deep ice core and to investigate climate and ice-flow histories in the vicinity of the Western Divide
II. Glacier-climate interactions
Glacier records contain a non-linear transformation of past climate. Our research is directed toward understanding climate-glacier interactions with the goal of using the glacier record to interpret patterns of past climate, necessary for predicting responses to future changes. We have developed models of snow accumulation and ablation; the models use upper atmospheric reanalysis data that are available over the entire world at 12-hour intervals on 180 km grid spacing. We have used the measurements and models to study climate and mass balance variations of Blue Glacier in the Olympic National Park in Western Washington, USA.
In collaboration with colleagues from Norway, we have adapted this approach to investigate climate and glacier variations in Scandinavia.
In a related study, we collaborated with colleagues from Nagoya University in Japan who study glaciers in the Himalaya. With them, we used radio echo-sounding methods to measure ice thickness of Khumbu and Lirung Glaciers in Nepal during May and June of 1999. These two glaciers are typical of the debris covered glaciers of Nepal. Our studies are motivated by the need to improve predictions of the response of these low-latitude glaciers to climate change.
We have also collaborated with Chilean colleagues and Eric Rignot (from the Jet Propulsion Laboratory) in a study of the Patagonian Icefields, which have been shrinking rapidly over the past century.
III. Basal processes at sub-freezing temperatures
Basal layers whose composition and mechanical properties differ markedly from that of overlying ice exist beneath many cold-based ice sheets and glaciers. These basal layers have important consequences for ice dynamics: (because high stress and temperature concentrate deformation there); for interpretation of ice cores (by limiting how close to the bed it is possible to obtain an undisturbed stratigraphic sequence); and for erosion and subsequent landform records left by past glaciations. In order to investigate the origin and properties of such layers, during the 1995-96 field season we excavated a 30-m long tunnel beneath Meserve Glacier, a small, cold-based alpine glacier on the south side of Wright Valley in Antarctica.
IV. Snow and avalanche related studies
Snow avalanches have a major impact on society, primarily through indirect costs associated with mitigation, litigation, insurance, and loss of both travel and business opportunities. I became interested in avalanches while working at Mt Cook National Park in New Zealand when it became clear that I should learn more about avalanches to increase my life expectancy. Over the past decade my students and I have worked with avalanche technicians at Snoqualmie Pass (in Western Washington) and the Milford Road (in New Zealand) to improve predictions of the timing, size and impact of snow avalanches.