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Role Of Transient Water Pressure In Quarrying: A Subglacial Experiment Using Acoustic Emissions, Denis Cohen, Thomas S. Hooyer, Neal R. Iverson, Jason Thomason, M. Jackson Sep 2006

Role Of Transient Water Pressure In Quarrying: A Subglacial Experiment Using Acoustic Emissions, Denis Cohen, Thomas S. Hooyer, Neal R. Iverson, Jason Thomason, M. Jackson

Geological and Atmospheric Sciences Publications

Probably the most important mechanism of glacial erosion is quarrying: the growth and coalescence of cracks in subglacial bedrock and dislodgement of resultant rock fragments. Although evidence indicates that erosion rates depend on sliding speed, rates of crack growth in bedrock may be enhanced by changing stresses on the bed caused by fluctuating basal water pressure in zones of ice-bed separation. To study quarrying in real time, a granite step, 12 cm high with a crack in its stoss surface, was installed at the bed of Engabreen, Norway. Acoustic emission sensors monitored crack growth events in the step as ice ...


One-Way Coupling Of An Atmospheric And A Hydrologic Model In Colorado, L. E. Hay, M. P. Clark, M. Pagowski, G. H. Leavesley, W. J. Gutowski Jr. Aug 2006

One-Way Coupling Of An Atmospheric And A Hydrologic Model In Colorado, L. E. Hay, M. P. Clark, M. Pagowski, G. H. Leavesley, W. J. Gutowski Jr.

Geological and Atmospheric Sciences Publications

This paper examines the accuracy of high-resolution nested mesoscale model simulations of surface climate. The nesting capabilities of the atmospheric fifth-generation Pennsylvania State University (PSU)–National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) were used to create high-resolution, 5-yr climate simulations (from 1 October 1994 through 30 September 1999), starting with a coarse nest of 20 km for the western United States. During this 5-yr period, two finer-resolution nests (5 and 1.7 km) were run over the Yampa River basin in northwestern Colorado. Raw and bias-corrected daily precipitation and maximum and minimum temperature time series from the three ...


Groundwater-Supported Evapotranspiration Within Glaciated Watersheds Under Conditions Of Climate Change, Denis Cohen, Mark Person, Ronnie Daannen, Sharon Locke, Dave Dahlstrom, Victor Zabielski, Thomas C. Winter, Donald Rosenberry, Herb Wright, Emi Ito, John L. Nieber, William J. Gutowski Jr. Apr 2006

Groundwater-Supported Evapotranspiration Within Glaciated Watersheds Under Conditions Of Climate Change, Denis Cohen, Mark Person, Ronnie Daannen, Sharon Locke, Dave Dahlstrom, Victor Zabielski, Thomas C. Winter, Donald Rosenberry, Herb Wright, Emi Ito, John L. Nieber, William J. Gutowski Jr.

Geological and Atmospheric Sciences Publications

This paper analyzes the effects of geology and geomorphology on surface-water/-groundwater interactions, evapotranspiration, and recharge under conditions of long-term climatic change. Our analysis uses hydrologic data from the glaciated Crow Wing watershed in central Minnesota, USA, combined with a hydrologic model of transient coupled unsaturated/saturated flow (HYDRAT2D). Analysis of historical water-table (1970–1993) and lake-level (1924–2002) records indicates that larger amplitude and longer period fluctuations occur within the upland portions of watersheds due to the response of the aquifer system to relatively short-term climatic fluctuations. Under drought conditions, lake and water-table levels fell by as much as ...


Testing A Glacial Erosion Rule Using Hang Heights Of Hanging Valleys, Jasper National Park, Alberta, Canada, J. M. Amundson, Neal R. Iverson Mar 2006

Testing A Glacial Erosion Rule Using Hang Heights Of Hanging Valleys, Jasper National Park, Alberta, Canada, J. M. Amundson, Neal R. Iverson

Geological and Atmospheric Sciences Publications

In most models of glacial erosion, glacier sliding velocity is hypothesized to control rates of bedrock erosion. If this hypothesis is correct, then the elevation difference between hanging and trunk valley floors, the hang height, should be dictated by the relative sliding velocities of the glaciers that occupied these valleys. By considering sliding velocity to be proportional to balance velocity and using mass continuity, hang height is expressed in terms of glacier catchment areas, slopes, and widths, which can be estimated for past glaciers from the morphology of glacial valleys. These parameters were estimated for 46 hanging valleys and their ...


Simulations Of Present And Future Climates In The Western United States With Four Nested Regional Climate Models, P. B. Duffy, R. W. Arritt, J. Coquard, W. Gutowski, J. Han, J. Iorio, J. Kim, L.-R. Leung, J. Roads, E. Zeledon Mar 2006

Simulations Of Present And Future Climates In The Western United States With Four Nested Regional Climate Models, P. B. Duffy, R. W. Arritt, J. Coquard, W. Gutowski, J. Han, J. Iorio, J. Kim, L.-R. Leung, J. Roads, E. Zeledon

Geological and Atmospheric Sciences Publications

In this paper, the authors analyze simulations of present and future climates in the western United States performed with four regional climate models (RCMs) nested within two global ocean–atmosphere climate models. The primary goal here is to assess the range of regional climate responses to increased greenhouse gases in available RCM simulations. The four RCMs used different geographical domains, different increased greenhouse gas scenarios for future-climate simulations, and (in some cases) different lateral boundary conditions. For simulations of the present climate, RCM results are compared to observations and to results of the GCM that provided lateral boundary conditions to ...


Bridge Frost Prediction By Heat And Mass Transfer Methods, Tina M. Greenfield, Eugene S. Takle Mar 2006

Bridge Frost Prediction By Heat And Mass Transfer Methods, Tina M. Greenfield, Eugene S. Takle

Geological and Atmospheric Sciences Publications

Frost on roadways and bridges can present hazardous conditions to motorists, particularly when it occurs in patches or on bridges when adjacent roadways are clear of frost. To minimize materials costs, vehicle corrosion, and negative environmental impacts, frost-suppression chemicals should be applied only when, where, and in the appropriate amounts needed to maintain roadways in a safe condition for motorists. Accurate forecasts of frost onset times, frost intensity, and frost disappearance (e.g., melting or sublimation) are needed to help roadway maintenance personnel decide when, where, and how much frost-suppression chemical to use. A finite-difference algorithm (BridgeT) has been developed ...


A Virtual Tornadic Thunderstorm Enabling Students To Construct Knowledge About Storm Dynamics Through Data Collection And Analysis, William A. Gallus Jr., Cinzia Cervato, Carolina Cruz-Neira, Galen William Faidley Jan 2006

A Virtual Tornadic Thunderstorm Enabling Students To Construct Knowledge About Storm Dynamics Through Data Collection And Analysis, William A. Gallus Jr., Cinzia Cervato, Carolina Cruz-Neira, Galen William Faidley

Geological and Atmospheric Sciences Publications

A visually realistic tornadic supercell thunderstorm has been constructed in a fully immersive virtual reality environment to allow students to better understand the complex small-scale dynamics present in such a storm through data probing. Less-immersive versions have been created that run on PCs, facilitating broader dissemination. The activity has been tested in introductory meteorology classes over the last four years. An exercise involving the virtual storm was first used by a subset of students from a large introductory meteorology course in spring 2002. Surveys were used at that time to evaluate the impact of this activity as a constructivist learning ...


The Use Of A Modified Ebert-Mcbride Technique To Evaluate Mesoscale Model Qpf As A Function Of Convective System Morphology During Ihop 2002, Jeremy S. Grams, William A. Gallus Jr., Steven E. Koch, Linda S. Wharton, Andrew Loughe, Elizabeth E. Ebert Jan 2006

The Use Of A Modified Ebert-Mcbride Technique To Evaluate Mesoscale Model Qpf As A Function Of Convective System Morphology During Ihop 2002, Jeremy S. Grams, William A. Gallus Jr., Steven E. Koch, Linda S. Wharton, Andrew Loughe, Elizabeth E. Ebert

Geological and Atmospheric Sciences Publications

The Ebert-McBride technique (EMT) is an entity-oriented method useful for quantitative precipitation verification. The EMT was modified to optimize its ability to identify contiguous rain areas (CRAs) during the 2002 International H2O Project (IHOP). This technique was then used to identify systematic sources of error as a function of observed convective system morphology in three 12-km model simulations run over the IHOP domain: Eta, the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5), and the Weather Research and Forecasting (WRF). The EMT was fine-tuned to optimize the pattern matching of forecasts to observations for the scales of precipitation systems observed during ...


Upper Mississippi River Basin Modeling System Part 4: Climate Change Impacts On Flow And Water Quality, Eugene S. Takle, Chris Anderson, Manoj Jha, Philip W. Gassman Jan 2006

Upper Mississippi River Basin Modeling System Part 4: Climate Change Impacts On Flow And Water Quality, Eugene S. Takle, Chris Anderson, Manoj Jha, Philip W. Gassman

Geological and Atmospheric Sciences Publications

Output from an ensemble of seven global climate models for contemporary and future scenario climates was used to drive the Soil and Water Assessment Tool (SWAT) to examine components of the hydrologic budget for the Upper Mississippi River Basin (UMRB). Results showed only modest increases in precipitation (+6%) and streamflow (+3%) but substantial reduction in snowfall (-37%) for the UMRB for the end of the 21st century. The low-resolution of global models contribute to the biases in some but not all hydrologic components, most notably evapotranspiration, potential evapotranspiration, and baseflow. Ensemble results indicate an increase in baseflow (+12%) and ...


Comparison Of Impacts Of Wrf Dynamic Core, Physics Package, And Initial Conditions On Warm Season Rainfall Forecasts, William A. Gallus Jr., James F. Bresch Jan 2006

Comparison Of Impacts Of Wrf Dynamic Core, Physics Package, And Initial Conditions On Warm Season Rainfall Forecasts, William A. Gallus Jr., James F. Bresch

Geological and Atmospheric Sciences Publications

A series of simulations for 15 events occurring during August 2002 were performed using the Weather Research and Forecasting (WRF) model over a domain encompassing most of the central United States to compare the sensitivity of warm season rainfall forecasts with changes in model physics, dynamics, and initial conditions. Most simulations were run with 8-km grid spacing. The Advanced Research WRF (ARW) and the nonhydrostatic mesoscale model (NMM) dynamic cores were used. One physics package (denoted NCEP) used the Betts–Miller–Janjic convective scheme with the Mellor–Yamada–Janjic planetary boundary layer (PBL) scheme and GFDL radiation package; the other ...