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- McMurdo Dry Valleys (Antarctica) (9)
- Climatic changes (5)
- Glaciers -- Climatic factors (5)
- Glaciers -- Antarctica (4)
- Glaciers -- Antarctica -- Taylor Valley (4)
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- Glaciers -- Environmental aspects (4)
- Meltwater -- Antarctica -- McMurdo Dry Valleys (4)
- Ablation (Aerothermodynamics) (3)
- Cryoconite (3)
- Glaciers -- Antarctica -- McMurdo Dry Valleys (3)
- Ice sheets -- Antarctica (3)
- Antarctica -- Environmental conditions (2)
- Biogeochemistry -- Cold regions (2)
- Carbon cycle (Biogeochemistry) (2)
- Climatic changes -- North Cascades (B.C. and Wash.) (2)
- Glacial climates (2)
- Glacial climates -- Antarctica (2)
- Glacier mass balance (2)
- Glaciers (2)
- Glaciers -- Climatic factors -- Arctic regions (2)
- Glaciers -- Climatic factors -- Washington (State) (2)
- Glaciers -- Ecological aspects (2)
- Glaciers -- Ecology -- Antarctica (2)
- Glaciers -- Inventories -- West (U.S.) (2)
- Glaciers -- Measurement (2)
- Glaciers -- Microbiology (2)
- Glaciers -- Research -- United States (2)
- Glaciers -- United States -- Measurement (2)
- Glaciers -- West (U.S.) -- Measurement (2)
- Glaciology -- North Cascades (B.C. and Wash.) (2)
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Articles 31 - 60 of 60
Full-Text Articles in Physical Sciences and Mathematics
Near-Surface Internal Melting: A Substantial Mass Loss On Antarctic Dry Valley Glaciers, Matthew J. Hoffman, Andrew G. Fountain, Glen E. Liston
Near-Surface Internal Melting: A Substantial Mass Loss On Antarctic Dry Valley Glaciers, Matthew J. Hoffman, Andrew G. Fountain, Glen E. Liston
Geology Faculty Publications and Presentations
The McMurdo Dry Valleys, southern Victoria Land, East Antarctica, are a polar desert, and melt from glacial ice is the primary source of water to streams, lakes and associated ecosystems. Previous work found that to adequately model glacier ablation and subsurface ice temperatures with a surface energy-balance model required including the transmission of solar radiation into the ice. Here we investigate the contribution of subsurface melt to the mass balance of (and runoff from) Dry Valley glaciers by including a drainage process in the model and applying the model to three glacier sites using 13years of hourly meteorological data. Model …
A Data Set Of Worldwide Glacier Length Fluctuations, Paul W. Leclercq, Johannes Oerlemans, Hassan J. Basagic, Christina Bushueva, A. J. Cook, Raymond Le Bris
A Data Set Of Worldwide Glacier Length Fluctuations, Paul W. Leclercq, Johannes Oerlemans, Hassan J. Basagic, Christina Bushueva, A. J. Cook, Raymond Le Bris
Geology Faculty Publications and Presentations
Glacier fluctuations contribute to variations in sea level and historical glacier length fluctuations are natural indicators of past climate change. To study these subjects, longterm information of glacier change is needed. In this paper we present a data set of global long-term glacier length fluctuations. The data set is a compilation of available information on changes in glacier length worldwide, including both measured and reconstructed glacier length fluctuations. All 471 length series start before 1950 and cover at least four decades. The longest record starts in 1535, but the majority of time series start after 1850. The number of available …
Accelerated Thermokarst Formation In The Mcmurdo Dry Valleys, Antarctica, Joseph S. Levy, Andrew G. Fountain, James L. Dickson, James W. Head, Marianne Okal, David R. Marchant, Jaclyn Watters
Accelerated Thermokarst Formation In The Mcmurdo Dry Valleys, Antarctica, Joseph S. Levy, Andrew G. Fountain, James L. Dickson, James W. Head, Marianne Okal, David R. Marchant, Jaclyn Watters
Geology Faculty Publications and Presentations
Thermokarst is a land surface lowered and disrupted by melting ground ice. Thermokarst is a major driver of landscape change in the Arctic, but has been considered to be a minor process in Antarctica. Here, we use ground-based and airborne LiDAR coupled with timelapse imaging and meteorological data to show that 1) thermokarst formation has accelerated in Garwood Valley, Antarctica; 2) the rate of thermokarst erosion is presently,10 times the average Holocene rate; and 3) the increased rate of thermokarst formation is driven most strongly by increasing insolation and sediment/albedo feedbacks. This suggests that sediment enhancement of insolation-driven melting may …
Grounding Zone Processes: Ice Mechanics And Margin Lakes, Kamb Ice Stream And Whillans Ice Stream, West Antarctica, Mason Joseph Fried
Grounding Zone Processes: Ice Mechanics And Margin Lakes, Kamb Ice Stream And Whillans Ice Stream, West Antarctica, Mason Joseph Fried
Dissertations and Theses
The lateral "corners" where Kamb and Whillans Ice Streams (KIS and WIS) discharge into the Ross Ice Shelf share common geometries and ice mechanical settings. At both corners of the now-stagnant KIS outlet, shear margins of apparently different ages confine regions with a relatively flat, smooth surface expression. These features are called the "Duckfoot" on the northern, right-lateral side and the "Goosefoot" on the other. It has been suggested, on evidence found in ice internal layers, that the flat ice terrains on KIS were afloat in the recent past, at a time when the ice stream grounding line was upstream …
Glacier Change In The North Cascades, Washington: 1900-2009, Kristina Amanda Dick
Glacier Change In The North Cascades, Washington: 1900-2009, Kristina Amanda Dick
Dissertations and Theses
Glaciers respond to local climate changes making them important indicators of regional climate change. The North Cascades region of Washington is the most glaciated region in the lower-48 states with approximately 25% of all glaciers and 40% of the total ice-covered area. While there are many on-going investigations of specific glaciers, little research has addressed the entire glacier cover of the region. A reference inventory of glaciers was derived from a comparison of two different inventories dating to about 1958. The different inventories agree within 93% of total number of glaciers and 94% of total ice-covered area. To quantify glacier …
Investigations Into The Regional And Local Timescale Variations Of Subglacial Drainage Networks, Justin Hiester
Investigations Into The Regional And Local Timescale Variations Of Subglacial Drainage Networks, Justin Hiester
Dissertations and Theses
Subglacial water plays an important role in the regulation of an ice sheet's mass balance. It may be the dominant control on the velocities of ice streams and outlet glaciers on scales of months to millennia. Recent satellite observations of ice surface elevation changes have given researchers new insights into how subglacial water is stored and transported. Localized uplift and settling of the ice surface implies that lakes exist beneath the ice sheet that are being filled and drained on relatively short time scales. %At the base of an ice sheet water can be transported through a variety of drainage …
Impact And Signatures Of Deglaciation On The Cryosphere, Landscape, And Habitability Of Earth And Mars, Nathalie A. Cabrol, Andrew G. Fountain, J. S. Kargel
Impact And Signatures Of Deglaciation On The Cryosphere, Landscape, And Habitability Of Earth And Mars, Nathalie A. Cabrol, Andrew G. Fountain, J. S. Kargel
Geology Faculty Publications and Presentations
Science questions can help bridge Astrobiology and Earth Science disciples around the theme of planetary deglaciation.
Do Cryoconite Holes Have The Potential To Be Significant Sources Of C, N, And P To Downstream Depauperate Ecosystems Of Taylor Valley, Antarctica?, Elizabeth A. Bagshaw, Martyn Tranter, Andrew G. Fountain, Kathleen A. Welch, Hassan J. Basagic, W. Berry Lyons
Do Cryoconite Holes Have The Potential To Be Significant Sources Of C, N, And P To Downstream Depauperate Ecosystems Of Taylor Valley, Antarctica?, Elizabeth A. Bagshaw, Martyn Tranter, Andrew G. Fountain, Kathleen A. Welch, Hassan J. Basagic, W. Berry Lyons
Geology Faculty Publications and Presentations
Nutrient recycling occurs in hydrologically isolated cryoconite holes on the glaciers of the McMurdo Dry Valleys, Antarctica. Biogeochemical processes enrich the cryoconite holes with solute and nutrients compared to the source sediment and glacier ice. The position of the glacier within the landscape affects the physical and biogeochemical character of the cryoconite holes, with those found in more biologically productive areas of the valley having higher concentrations of C, N, and P and higher pH. Comprehensive assessment of the quality and quantity of bioavailable C, N, and P shows that the cryoconite holes represent a significant store of nutrient in …
Investigating The Holocene History Of Eliot Glacier, Mount Hood, Oregon, Nadia Sittara Jones
Investigating The Holocene History Of Eliot Glacier, Mount Hood, Oregon, Nadia Sittara Jones
Dissertations and Theses
This research documents the Holocene glacial history of Mount Hood, Cascade Mountains, Oregon by analyzing a set of three lateral moraines abutting Eliot Glacier, the largest glacier on the mountain. This study seeks to: 1) establish the relative ages of these lateral moraines and 2) determine if these features represent distinct glacial advances. The hypothesis is that the lateral moraines for Eliot Glacier represent three distinct periods of glacial advance based on their position relative to the current glacier and other diagnostic indicators. Soil profiles of three positions (shoulder, backslope, and footslope) on the distal side of each lateral moraine …
Late Pleistocene And Holocene Aged Glacial And Climatic Reconstructions In The Goat Rocks Wilderness, Washington, United States, Joshua Andrews Heard
Late Pleistocene And Holocene Aged Glacial And Climatic Reconstructions In The Goat Rocks Wilderness, Washington, United States, Joshua Andrews Heard
Dissertations and Theses
Eight glaciers, covering an area of 1.63 km2, reside on the northern and northeastern slopes of the Goat Rocks tallest peaks in the Cascades of central Washington. At least three glacial stands occurred downstream from these glaciers. Closest to modern glacier termini are Little Ice Age (LIA) moraines that were deposited between 1870 and 1899 AD, according to the lichenometric analysis. They are characterized by sharp, minimally eroded crests, little to no soil cover, and minimal vegetation cover. Glacier reconstructions indicate that LIA glaciers covered 8.29 km2, 76% more area than modern ice coverage. The average LIA equilibrium line altitude …
Quantifying 20th Century Glacier Change In The Sierra Nevada, California, Andrew G. Fountain, Hassan J. Basagic
Quantifying 20th Century Glacier Change In The Sierra Nevada, California, Andrew G. Fountain, Hassan J. Basagic
Geology Faculty Publications and Presentations
Numerous small alpine glaciers occupy the high elevation regions of the central and southern Sierra Nevada, California. An inventory based on 1:24,000 topographic maps revealed 1719 glaciers and perennial snowfields for a total area of 39.15 +/- 0.13 km(2). The number of 'true' glaciers, versus non-moving ice, is estimated to be 122 covering 14.89 +/- 0.08 km(2) or 38% of the ice-covered area. Historic photographs, geologic evidence, and field mapping were used to determine the magnitude of area change over the past century at 14 glaciers. The area change between 1903 and 2004 ranged from -31% to -78%, averaging -55%. …
Women In Glaciology, An Historical Perspective, Christina L. Hulbe, Weili Wang, Simon Ommanney
Women In Glaciology, An Historical Perspective, Christina L. Hulbe, Weili Wang, Simon Ommanney
Geology Faculty Publications and Presentations
Women's history in glaciology extends as far back in time as the discipline itself, although their contributions to the scientific discourse have for all of that history been constrained by the sociopolitical contexts of the times. The first Journal of Glaciology paper authored by a woman appeared in 1948, within a year of the founding of the Journal, but it was not until the 1980s that women produced more than a few percent of Journal and Annals of Glaciology papers. Here international perspectives on women's participation in the sciences are presented in order to establish an economic and sociopolitical context …
Grounding-Line Basal Melt Rates Determined Using Radar-Derived Internal Stratigraphy, Ginny Catania, Christina L. Hulbe, Howard Conway
Grounding-Line Basal Melt Rates Determined Using Radar-Derived Internal Stratigraphy, Ginny Catania, Christina L. Hulbe, Howard Conway
Geology Faculty Publications and Presentations
We use ice-penetrating radar data across grounding lines of Siple Dome and Roosevelt Island, Antarctica, to measure the spatial pattern, magnitude and duration of sub-ice-shelf melting at these locations. Stratigraphic layers across the grounding line show, in places, a large-amplitude downwarp at, or slightly downstream of, the grounding line due to sub-ice-shelf basal melting. Localized downwarping indicates that melting is transient; melt rates, or the grounding line position, have changed within a few hundred years in order to produce the observed stratigraphy. Elsewhere, no meltrelated stratigraphic signature is preserved. In part, heterogeneity in the amount of sub-ice-shelf melt is due …
Propagation Of Long Fractures In The Ronne Ice Shelf Investigated Using A Numerical Model Of Fracture Propagation, Christina L. Hulbe, Christine Marie Ledoux, Kenneth M. Cruikshank
Propagation Of Long Fractures In The Ronne Ice Shelf Investigated Using A Numerical Model Of Fracture Propagation, Christina L. Hulbe, Christine Marie Ledoux, Kenneth M. Cruikshank
Geology Faculty Publications and Presentations
Long rifts near the front of the Ronne Ice Shelf, Antarctica, are observed to begin as fractures along the lateral boundaries of outlet streams feeding the shelf. These flaws eventually become the planes along which tabular icebergs calve. The fractures propagate laterally as they advect through the shelf, with orientations that can be explained by the glaciological stress field. Fracture length remains constrained over much of the advective path, and locations of crack tip arrest are observed to coincide with structural boundaries, such as suture zones between ice from adjacent outlet glaciers. Geomechanical principles and numerical models demonstrate that in …
A Dynamic Physical Model For Soil Temperature And Water In Taylor Valley, Antarctica, H. W. Hunt, Andrew G. Fountain, Peter T. Doran, Hassan J. Basagic
A Dynamic Physical Model For Soil Temperature And Water In Taylor Valley, Antarctica, H. W. Hunt, Andrew G. Fountain, Peter T. Doran, Hassan J. Basagic
Geography Faculty Publications and Presentations
We developed a simulation model for terrestrial sites including sensible heat exchange between the atmosphere and ground surface, inter- and intra-layer heat conduction by rock and soil, and shortwave and longwave radiation. Water fluxes included snowmelt, freezing/thawing of soil water, soil capillary flow, and vapour flows among atmosphere, soil, and snow. The model accounted for 96-99% of variation in soil temperature data. No long-term temporal trends in soil temperature were apparent. Soil water vapour concentration in thawed surface soil in summer often was higher than in frozen deeper soils, leading to downward vapour fluxes. Katabatic winds caused a reversal of …
The ‘Benchmark Glacier’ Concept – Does It Work? Lessons From The North Cascade Range, Usa, Andrew G. Fountain, Matthew J. Hoffman, Frank Granshaw, Jon L. Riedel
The ‘Benchmark Glacier’ Concept – Does It Work? Lessons From The North Cascade Range, Usa, Andrew G. Fountain, Matthew J. Hoffman, Frank Granshaw, Jon L. Riedel
Geology Faculty Publications and Presentations
Benchmark glaciers were established in many alpine areas during the 1960s as part of the International Hydrological Decade to represent ‘typical’ mass and energy processes on glaciers in different climatic regions around the world. These glaciers have received new interest in the past decade because they are used to infer the contribution of alpine glacier wastage to global sea-level rise. We compare South Cascade Glacier, the benchmark glacier for the northwest contiguous USA, and four other secondary glaciers, against the topographic, area and mass changes of 321 glaciers in the surrounding region. Results show that South Cascade Glacier is unusually …
Surface Energy Balance And Melt Thresholds Over 11 Years At Taylor Glacier, Antarctica, Matthew James Hoffman, Andrew G. Fountain, Glen E. Liston
Surface Energy Balance And Melt Thresholds Over 11 Years At Taylor Glacier, Antarctica, Matthew James Hoffman, Andrew G. Fountain, Glen E. Liston
Geography Faculty Publications and Presentations
In the McMurdo Dry Valleys, Victoria Land, Antarctica, melting of glacial ice is the primary source of water to streams, lakes, and associated ecosystems. To understand geochemical fluxes and ecological responses to past and future climates requires a physically based energy balance model. We applied a one-dimensional model to one site on Taylor Glacier using 11 years of daily meteorological data and seasonal ablation measurements. Inclusion of transmission of solar radiation into the ice was necessary to accurately model summer ablation and ice temperatures. Results showed good correspondence between calculated and measured ablation and ice temperatures over the 11 years. …
Temporal Variations In Physical And Chemical Features Of Cryoconite Holes On Canada Glacier, Mcmurdo Dry Valleys, Antarctica, Andrew G. Fountain, Thomas H. Nylen, Martyn Tranter, Elizabeth A. Bagshaw
Temporal Variations In Physical And Chemical Features Of Cryoconite Holes On Canada Glacier, Mcmurdo Dry Valleys, Antarctica, Andrew G. Fountain, Thomas H. Nylen, Martyn Tranter, Elizabeth A. Bagshaw
Geography Faculty Publications and Presentations
Cryoconite holes in the McMurdo Dry Valleys are ice-lidded, thus isolating the pools of water from the atmosphere and from potential surface melt. Hourly measurements of ice and water temperature and water electrical conductivity (EC) were recorded to broadly characterize the physical and chemical changes on daily to seasonal timescales. Overall, subsurface ice/water temperatures were typically several degrees warmer than air temperatures, underscoring the importance of subsurface solar heating. At no time was surface melt observed and the holes melted from within. Detailed differences in the timing and magnitude of both temperature and EC variations during melt-out and freezeup existed …
Introduction To Special Section On Microcosms In Ice: The Biogeochemistry Of Cryoconite Holes, Andrew G. Fountain, Martyn Tranter
Introduction To Special Section On Microcosms In Ice: The Biogeochemistry Of Cryoconite Holes, Andrew G. Fountain, Martyn Tranter
Geology Faculty Publications and Presentations
Cryoconite holes are small, water filled, cylindrical melt-holes on glacial ice surface. Cryoconite, 'cold dust,' refers to the thin layer of sediment at the hole bottom. The holes form from surficial sediment patches that absorbs more solar radiation than the surrounding ice and which preferentially melt into the glacier forming a cylindrical water-filled hole. These holes form on the ice-covered, as opposed to snow covered, parts of glaciers world-wide, wherever there is sufficient energy for melting. Biogeochemically, cryoconite holes are interesting because the sediment is inncoculated with biologic material, a fraction of which thrives in the cryoconite environment of near-freezing …
Hydrologic Response To Extreme Warm And Cold Summers In The Mcmurdo Dry Valleys, East Antarctica, Peter T. Doran, Christopher P. Mckay, Andrew G. Fountain, Thomas H. Nylen, Diane M. Mcknight, Chris Jaros, John E. Barrett
Hydrologic Response To Extreme Warm And Cold Summers In The Mcmurdo Dry Valleys, East Antarctica, Peter T. Doran, Christopher P. Mckay, Andrew G. Fountain, Thomas H. Nylen, Diane M. Mcknight, Chris Jaros, John E. Barrett
Geography Faculty Publications and Presentations
The meteorological characteristics and hydrological response of an extreme warm, and cold summer in the McMurdo Dry Valleys are compared. The driver behind the warmer summer conditions was the occurrence of down-valley winds, which were not present during the colder summer. Occurrence of the summer down-valley winds coincided with lower than typical mean sea level pressure in the Ross Sea region. There was no significant difference in the amount of solar radiation received during the two summers. Compared to the cold summer, glaciological and hydrological response to the warm summer in Taylor Valley included significant glacier mass loss, and 3- …
Quantifying Twentieth Century Glacier Change In The Sierra Nevada, California, Hassan J. Basagic
Quantifying Twentieth Century Glacier Change In The Sierra Nevada, California, Hassan J. Basagic
Dissertations and Theses
Numerous small alpine glaciers occupy the high elevation regions of the central and southern Siena Nevada, California. These glaciers change size in response to variations in climate and are therefore important indicators of climate change. An inventory based on USGS topographic maps (l :24,000) revealed 1719 glaciers and perennial snow and ice features for a total area of 39.l5 ±7.52 km2. The number of 'true' glaciers, versus non-moving ice, is estimated to be 118, covering 15.87 ± 1.69 Km2. All glaciers were located on north to northeast aspects, at elevations >3000 m. Historical photographs, geologic evidence, …
Biogeochemical Evolution Of Cryoconite Holes On Canada Glacier, Taylor Valley, Antarctica, Elizabeth A. Bagshaw, Martyn Tranter, Andrew G. Fountain, Kathleen A. Welch, Hassan J. Basagic, W. Berry Lyons
Biogeochemical Evolution Of Cryoconite Holes On Canada Glacier, Taylor Valley, Antarctica, Elizabeth A. Bagshaw, Martyn Tranter, Andrew G. Fountain, Kathleen A. Welch, Hassan J. Basagic, W. Berry Lyons
Geography Faculty Publications and Presentations
The cryoconite holes of the McMurdo Dry Valleys are simple, closed biogeochemical systems involving water, ice, mineral and organic debris, which serve as ecosystems for consortia of microorganisms. This study is the first to document the seasonal and annual chemical evolution of solutes in cryoconite holes. Samples of glacier ice, frozen cryoconite holes and those containing water were collected during the austral summer of 2005–2006. The isolation age was calculated from the excess Cl‾ in the holes, and varied from 0 to 5 years (a), consistent with the last hot summer when the cryoconite holes were open to the atmosphere. …
Biogeochemical Stoichiometry Of Antarctic Dry Valley Ecosystems, John E. Barrett, Ross A. Virginia, W. Berry Lyons, Diane M. Mcknight, John Charles Priscu, Peter T. Doran, Andrew G. Fountain, Diana H. Wall, D. L. Moorhead
Biogeochemical Stoichiometry Of Antarctic Dry Valley Ecosystems, John E. Barrett, Ross A. Virginia, W. Berry Lyons, Diane M. Mcknight, John Charles Priscu, Peter T. Doran, Andrew G. Fountain, Diana H. Wall, D. L. Moorhead
Geography Faculty Publications and Presentations
Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–10⁶ years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated …
A Stable Isotopic Investigation Of A Polar Desert Hydrologic System, Mcmurdo Dry Valleys, Antarctica, Michael N. Gooseff, W. Berry Lyons, Diane M. Mcknight, Bruce H. Vaughn, Andrew G. Fountain, Carolyn Dowling
A Stable Isotopic Investigation Of A Polar Desert Hydrologic System, Mcmurdo Dry Valleys, Antarctica, Michael N. Gooseff, W. Berry Lyons, Diane M. Mcknight, Bruce H. Vaughn, Andrew G. Fountain, Carolyn Dowling
Geology Faculty Publications and Presentations
The hydrologic system of the coastal McMurdo Dry Valleys, Antarctica, is defined by snow accumulation, glacier melt, stream flow, and retention in closed-basin, ice-covered lakes. During the austral summers from 1993-1996 and 1999-2000 to 2002-2003, fresh snow, snow pits, glacier ice, stream water, and lake waters were sampled for the stable isotopes deuterium (D) and 18O in order to resolve sources of meltwater and the interactions among the various hydrologic reservoirs in the dry valleys. This data set provides a survey of the distribution of natural water isotope abundances within the well-defined dry valley hydrologic system in Taylor Valley, which …
A Tale Of Three Sisters: Reconstructing The Holocene Glacial History And Paleoclimate Record At Three Sisters Volcanoes, Oregon, United States, Shaun Andrew Marcott
A Tale Of Three Sisters: Reconstructing The Holocene Glacial History And Paleoclimate Record At Three Sisters Volcanoes, Oregon, United States, Shaun Andrew Marcott
Dissertations and Theses
At least four glacial stands occurred since 6.5 ka B.P. based on moraines located on the eastern flanks of the Three Sisters Volcanoes and the northern flanks of Broken Top Mountain in the Central Oregon Cascades. The youngest of these advances was the Little Ice Age (LIA) glaciation, which reached its maximum advance 150-200 yrs. B.P. and is defined by the large sharp crested and unvegetated moraines adjacent to the modern glaciers. In isolated locations less than 100 m downslope from these moraines, a second set of sparsely vegetated lateral moraines marks the Late-Neoglacial stand of the glaciers between 2.1 …
The Role Of Lateral And Vertical Shear In Tributary Flow Toward A West Antarctic Ice Stream, Christina L. Hulbe, Weili Wang, Ian R. Joughin, Martin J. Siegert
The Role Of Lateral And Vertical Shear In Tributary Flow Toward A West Antarctic Ice Stream, Christina L. Hulbe, Weili Wang, Ian R. Joughin, Martin J. Siegert
Geology Faculty Publications and Presentations
Narrow lateral shear margins are the most distinctive visual feature of the West Antarctic ice streams. Large shear stresses within these layers support the majority of the gravitational driving stress within a fast-flowing ice stream.The present contribution looks upstream, to the tributaries that feed ice-stream onsets, and considers the effects of both horizontal and vertical shear on their flow. Numerical and direct simulations of vertical and horizontal shear are used.Vertical shear, simulated using an anisotropic flow law, is of particular interest.We conclude that by isolating overlying ice from large-amplitude variations in bed elevation -vertical shear margins - play an important …
The Link Between Climate Warming And Break-Up Of Ice Shelves In The Antarctic Peninsula, Ted A. Scambos, Christina L. Hulbe, Mark A. Fahnestock, Jennifer Bohlander
The Link Between Climate Warming And Break-Up Of Ice Shelves In The Antarctic Peninsula, Ted A. Scambos, Christina L. Hulbe, Mark A. Fahnestock, Jennifer Bohlander
Geology Faculty Publications and Presentations
A review of in situ and remote-sensing data covering the ice shelves of the Antarctic Peninsula provides a series of characteristics closely associated with rapid shelf retreat: deeply embayed ice fronts; calving of myriad small elongate bergs in punctuated events; increasing flow speed; and the presence of melt ponds on the ice-shelf surface in the vicinity of the break-ups. As climate has warmed in the Antarctic Peninsula region, melt-season duration and the extent of ponding have increased. Most break-up events have occurred during longer melt seasons, suggesting that meltwater itself, not just warming, is responsible. Regions that show melting without …
Researchers Pool Knowledge About Antarctic Dry Valleys, Andrew G. Fountain, Sarah Spaulding
Researchers Pool Knowledge About Antarctic Dry Valleys, Andrew G. Fountain, Sarah Spaulding
Geology Faculty Publications and Presentations
Most of us think of ice when we think of the Antarctic, and rightly so, considering that only 5% of it is ice-free. Dry valleys--the ice-free areas--have sandy, rocky valley floors, ice-covered lakes, and streams that flow only two months of the year. The McMurdo Dry Valleys (78øS 163øE) are the largest of these regions.
A Strategy For Monitoring Glaciers, Andrew G. Fountain, Robert M. Krimmel, Dennis C. Trabant
A Strategy For Monitoring Glaciers, Andrew G. Fountain, Robert M. Krimmel, Dennis C. Trabant
Geography Faculty Publications and Presentations
Glaciers are important features in the hydrologic cycle and affect the volume, variability, and water quality of runoff. Assessing and predicting the effect of glaciers on water resources require a monitoring program to provide basic data for this understanding. The monitoring program of the U.S. Geological Survey employs a nested approach whereby an intensively studied glacier is surrounded by less intensively studied glaciers and those monitored solely by remote sensing. Ideally, each glacierized region of the United States would have such a network of glaciers. The intensively studied glacier provides a detailed understanding of the physical processes and their temporal …
The Effect Of Glaciers On Streamflow Variations, Andrew G. Fountain, Wendell V. Tangborn
The Effect Of Glaciers On Streamflow Variations, Andrew G. Fountain, Wendell V. Tangborn
Geology Faculty Publications and Presentations
The effect of temperate glaciers on runoff variations is examined for the North Cascade Mountains of Washington State. The principal influences of glaciers on streamflow are often unexpected contributions to streamflow volume, a delay of the maximum seasonal flow, and a decrease in annual and monthly variation of runoff. The delay of maximum flow is caused by temporary englacial storage of spring meltwater and by peak meltwater production occurring in midsummer. The englacial storage, for one case, is 54% of the potential May runoff. An algorithm is presented that calculates the coefficient of variation of runoff for any arbitrary glacier …