Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on June 16, 2010). Includes bibliographical references (p. 61-64).

Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on May 6, 2010). Includes bibliographical references (p. 26-30).

Thesis (Ph.D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 123-128).

Drainage systems on cold-based glaciers are often thought to be simple systems that can be approximated from the supraglacial components of temperate glaciers. Most studies concerning cold-based glacier drainage systems have only considered one facet of the system, with little regard for how the system components interact. Studying each component independently of the whole system constrains our ability to model drainage system function and development. This in turn restricts our potential to predict how drainage systems of cold glaciers may respond to environmental change. The overarching aim of this thesis was to understand drainage system development of a cold-based glacier, and to assess whether our current understanding of supraglacial hydrological systems is consistent with the drainage systems that form on cold-based glaciers. This thesis evaluated the drainage system of the Wright Lower Glacier, McMurdo Dry Valleys, Antarctica, during the 2004/05, 2005/06 and 2006/07 ablation seasons. The study incorporated field, laboratory and numerical analyses, which resulted in a deeper understanding of the spatial and temporal variability of meltwater generation, drainage pathways, water stores and bulk discharge from the glacier. The findings showed that melt variability was driven by sediment and topographic variations, and that water storage in the form of cryoconite holes, intergranular flow, supraglacial ponds and refreezing dictated meltwater transmission to the glacier outlet. These results indicated that the structure, function and variability of the drainage system were inherently more complex than previous studies on supraglacial drainage systems had suggested. These new insights were combined together to construct a new conceptual model of the drainage system structure of a cold-based glacier. However, before the conceptual model can be used to produce a numerical model of drainage system function or development on cold-based glaciers, several issues need to be addressed. These include: refined methods for quantifying meltwater generation in cold, arid environments; methods to measure water storage on and under the glacier surface; further understanding of the development of permeable ice; and a better technique to quantify cryoconite hole connectivity.

This is the first large-scale modelling study of iceberg trajectories and melt rates in the Southern Ocean. An iceberg model _ was seeded with climatological iceberg calving rates based on a calculation of the net surface accumulation from each snow catchment area on the Antarctic continent. In most areas modelled trajectories show good agreement with observed patterns of iceberg motion, though discrepancies in the Weddell Sea have highlighted problems in the ocean general circulation model output used to force the iceberg model. The Coriolis force is found to be important in keeping bergs entrained in the coastal current around Antarctica, and topographic features are important in causing bergs to depart from the coastal regions. The modelled geographic distribution of iceberg meltwater joining the ocean has been calculated, and is found in many near coastal regions to be comparable in magnitude to the excess of precipitation over evaporation (P-E). A remote sensing study of icebergs has been carried out in two locations in the Weddell Sea using SAR. This study has, for the first time, been able to calculate iceberg fluxes from satellite. The southwestwards flux of icebergs within 20 km of the coast at around 18°W, based on a one month period of observations, has been calculated at 50 to 70 Gta-1 (1Gt = 1012kg). This is 4 to 5% of the total iceberg discharge from Antarctica. The question of Antarctic mass balance is considered through comparison of modelresults and observations. Although a conclusion is not reached here, plans are presented for an iceberg observing programme and further model development which could resolve the problem

Rising global air temperatures are causing increased melting across the surfaces of large ice masses such as the Greenland Ice Sheet and the ice caps of Arctic Canada. The fraction of this melt that refreezes within the snow and firn has a large spatial variability across the surfaces of these ice masses. This spatial variability is an important control on the surface mass balance, and has important implications for the interpretation of satellite radar altimetry data sets. The sensitivity of large ice masses to climate change depends on changes in the melt-runoff relationship, and changes in the spatial extents of surface snow zones within the accumulation zone. Therefore, this thesis develops a model used to calculate melt, near-surface refreezing and surface runoff across the surface of a large ice mass. The model is used to predict both stratigraphic changes and bulk snow and firn properties over a melt season across a transect of points. A high-resolution snow and firn data set from Devon Ice Cap is used to calibrate and validate the model. It is then run across a transect covering the entire altitude range of the ice cap for the summers of 2004 and 2006. The model matches measured trends in bulk snowpack variables across the transect in both years. Calculated fraction of melt running off is similar in both years at ~44%, though is sensitive to change in air temperature. Surface mass balance (including internal accumulation), found to be +0.26 Gt in 2004 and +0.18 Gt in 2006, changes in a parabolic way for a linear air temperature change. The model is then applied to the Greenland Ice Sheet without altering any of the calibrated parameters. It is run for two melt seasons, 2004 and 2005, over which model output compares well with measurements of snow depth, sub-surface density and altitudes of snow surface boundaries. The wet snow line responds in a linear way to change in air temperature, and the runoff line is sensitive to the specified depth within the firn of the impermeable layer. Over the next century, the model shows that the dry snow zone will disappear completely under moderate warming scenarios, and the percolation zone will also disappear under intense warming scenarios. Including a more complicated representation of vertical meltwater percolation through the snow and firn grid substantially alters modelled autumn density profiles, and produces more accurate values of meltwater percolation depth and ice fraction within the autumn snowpack. However, bulk snowpack properties are of similar accuracy to the un-modified model. Scaling up of the model, in both spatial and temporal terms, will make it useful for assistance in the interpretation of satellite radar altimetry data sets, as well as assessing future changes in the spatial variability of refreezing and runoff, reducing the uncertainty in long term surface mass balance predictions across large ice masses.

No description available.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 112-118).

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 75-83). Also available on the World Wide Web.

The spatial distribution of snowpack in relation to snow water equivalent (SWE) and covered extent is highly variable in time both seasonally and interannually. In order to assess basin water resources, SWE must be distributed to areal estimates. This spatially distributed SWE connects the point scale to the larger scale of the basin (i.e. macro-scale), requiring a combination approach of statistical interpolation techniques and snowpack extent constraint from remote sensing. This research connects those multiple spatial scales and applies the combined remote sensing and ground-based SWE products in a hydrologic model setting to aid in improving streamflow forecasting in the mountainous terrain of snowmelt-dominated basins, a current modeling gap. Four specific advancements were achieved: 1) a comprehensive assessment of spatial distribution techniques in interpolating point snow water equivalent (SWE) measurements at snow telemetry (SNOTEL) stations to the macro-scale was made and an optimal technique for distributing SWE on this scale was obtained; 2) differences between two major data sources of SWE (SNOTEL and snowcourse) were quantified for both point-scale variability and interpolated macro-scale variability to determine spatial and temporal differences in data sources for dry, average and wet years to better inform water resources management applications; 3) basin-scale estimates of ground-based SWE and snow covered area (SCA) from remote sensing were evaluated relative to equivalent fields calculated by a hydrologic model and the effect of assimilating the remote sensing products into the model were investigated; and 4) in the context of (3), improvements were made in macro-scale SCA estimates through both a canopy correction and a low pass statistical filter in an effort to correct for the relatively low resolution of remotely sensed estimates.