Matt HoffmanPh.D. Student hoffman <at> pdx.edu |
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Matt HoffmanPh.D. Student hoffman <at> pdx.edu |
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Dry Valley Melt Modeling. My Ph.D. research under Prof. Andrew Fountain involves developing a spatially-distributed melt model for the glaciers of the McMurdo Dry Valleys, Antarctica, for the purpose of estimating runoff for geochemical and ecological responses to past and future climates. The Dry Valleys are a polar desert, and melting of ice from the ablation zones of glaciers during the 6-week summer is the primary source of water to streams, lakes, and associated ecosystems. I am adapting a one-dimensional, physically-based surface energy balance model that includes the transmission of solar radiation within the glacier ice. The model is run and calibrated using over a decade of meteorological and glacier ablation measurements collected by the McMurdo Dry Valleys Long Term Ecological Project (MCM LTER), of which I am a part. The Dry Valley glaciers are on the threshold of melting, and spatial variations in ice characteristics (albedo, debris cover, bubble content) and microclimate (reduction of wind speed in the lee of topographic obstacles, orientation of the surface to the sun, shading from surrounding mountains) can potentially alter the quantity of melt by orders of magnitude. Additionally, because the glacier ablation zones are generally snow-free, their surface energy balance differs from the snow covered surfaces that comprise the majority of Antarctica, as well as from the melt-dominated ablation zones of temperate glaciers.
Glacier Change in the American West. I have been active in our research group's development of a database of the distribution and temporal change of glaciers in the American West (exclusive of Alaska). We have compiled an inventory of over 8000 glaciers and perennial snow and ice features across 8 states. In addition to working extensively on the design and construction of the inventory, I have also studied the glaciers of Colorado in more detail. I have written a detailed summary of the distribution of glaciers and other permenant ice features in Colorado; used historic maps, aerial photos, and ground-based photos to construct a record of twentieth century glacier change in Rocky Mountain National Park; and co-authored an interactive website exploring the glaciers and glacier change in Rocky Mountain National Park.
More Glacier Research at Portland State
Matthew J. Hoffman, Andrew G. Fountain, Glen E. Liston. Surface energy balance and melt thresholds over 11 years at Taylor Glacier, Antarctica. Journal of Geophysical Research-Earth Surface. 113, F04014, doi:10.1029/2008JF001029.
Andrew G. Fountain, Matthew J. Hoffman, Frank Granshaw, Jon Riedel. The Benchmark Glacier Concept - does it work? Lessons from the North Cascade Range, USA. Annals of Glaciology, vol. 50. p. 163-8.
Hoffman, M.J., Fountain, A.G., Achuff, J.M. 2007. Twentieth-century variations in area of cirque glaciers and glacierets, Rocky Mountain National Park , Rocky Mountains, Colorado, USA. Annals of Glaciology, 46, 349-354.
Fountain, Andrew G.; Hoffman, Matthew; Jackson, Keith; Basagic, Hassan; Nylen, Thomas; Percy, David. 2007. Digital Outlines and Topography of the Glaciers of the American West. USGS Open-File Report 2006-1340.
David Percy, Eric Hanson, Darrell Fuhriman, Cris Holm, William Garrick, Chris LeDoux, Matt Hoffman, and Andrew Fountain. 2006. Spatio-Temporal Asset Management in a Database of Glacier Change. Proceedings of the Geoinformatics Conference,
Soong, Ta Wei, and Matthew J. Hoffman. 2002. Effects of Riparian Tree Management on Flood Conveyance Study of Manning's Roughness in Vegetated Floodplains with an Application on the Embarras River in Illinois.
Hoffman, MJ. 2008. Reaching the threshold of melt: Taylor Glacier, McMurdo Dry Valleys. Northwest Glaciologists Meeting, Seattle, WA, October 17-18, 2008.
Fountain, A.G., Hoffman, M.J. 2008. The benchmark glacier concept – Does it work? International Glaciological Society Workshop on Mass balance mass balance measurements and modeling.
Hoffman, M.J. 2007. Glacier melt modeling at Taylor Glacier. Northwest Glaciologists Meeting.
Hoffman, M.J. 2007. Taylor Valley Glacier melt modeling: Progress and directions. McMurdo-Long-Term Ecological Research project Science Meeting.
G 374 Geomorphic Processes – Taught Lecture and Lab, Spring 2007 and 2006.