GLACIOLOGY

A Cooperative Ice Core Paleoclimate Study of Monsoon Variability as Archived in the Dasuopu Glacier, China
ATM 9523237
05/01/96; (ATM) $182,442, (INT) $50,000; 12 months
Ohio State University Research Foundation
Columbus, OH 43210-1016
Lonnie G. Thompson

This award supports the retrieval and analysis of ice cores from the tropical Dasuopu glacier located in the south central Himalayas, where conventional, long-term climatic data are completely absent. Tropical records are of particular interest because 50% of the global surface lies between 30°N and 30°S, and 75% of the Earth's population inhabits these climatically tropical lands. The records from these cores will complement the long histories recovered from the Dunde and Guliya ice caps on the northeastern and northwestern margins of the Qinghai­Tibetan (Q­T) Plateau. Located on the southern margin of the Q­T Plateau the new drilling site lies well within the spatial extent of the monsoon system. Dominance of monsoonal circulation produces distinctly annual cycles in oxygen isotopic ratios and in the deposition of visible dust, which permit the reconstruction of high resolution (annual) records of climatic and environmental conditions. Dasuopu is located just north of the Himalayas with annual precipitation of about 300 mm water equivalent (H2O eq.). The high elevation of this site ensures that ice temperatures will be well below OºC; hence this glacier may be "polar" in character and is likely to contain a long, well-preserved record. The initial field program includes a complement of geophysical and surface studies designed to determine the suitability of this glacier for the recovery of high resolution, well-preserved ice core records. Studies of the climate of China are plagued by the absence of data from major sections of the Q­T Plateau and the surrounding high mountain ranges. The successful retrieval of previous records (Dunde and Guliya) suggests that ice cores from carefully selected ice caps in Asia are excellent archives for climatic and environmental histories. These records are essential to fill one of the major spatial gaps in the Earth's climate history.

Implementation of a Pilot Global Geocryological Database at the World Data Center (WDC-A) Glaciology
ATM 9528007
05/01/96; (OPP) $30,000, (ATM) $30,000; 12 months
University of Colorado­Boulder
Boulder, CO 80309-0019
Roger G. Barry

This is a one-year grant to rescue, recover, archive and disseminate permafrost data that was collected in the former Soviet Union but is in danger of getting lost permanently. The project is guided by criteria for priority databases established by the International Permafrost Association (IPA) working group on permafrost data and information. This data is very valuable for climate research.

Inter-American Institute (IAI) Workshop: Climate Variability in the Americas from High Elevation Ice Cores
ATM 9530179
07/01/96; (ATM) $49,937; 12 months
University of Massachusetts­Amherst
Amherst, MA 01003
Raymond S. Bradley

The purpose of this workshop on Climate Variability in the Americas from High Elevation Ice Cores is to develop plans for obtaining a set of ice cores from sites distributed along the mountainous western axis of the Americas, from Alaska/Yukon to the southern tip of South America. Although most ice core research has been in polar regions, ice cores from high elevations in the Americas have also provided unique and detailed insights into paleoclimates of the past, and this workshop will build on the analysis which has been carried out in the past. The workshop will bring together interested parties from different research institutions in the region: Argentina, Bolivia, Brazil, Canada, Chile, Ecuador, Peru, and the United States. The primary goal of the workshop is to prepare a document outlining the opportunities that ice core studies in the high mountains of the Americas can provide in understanding El Niño Southern Oscillations (ENSO)-related interannual variability and cold region processes. The goal will be achieved by: identifying the principal scientific questions which can be answered by ice core studies; determining which ice caps have the potential of yielding high-resolution paleoenvironmental records; prioritizing the most important sites; planning preparatory glaciological and geophysical surveys to determine in detail the optimum coring sites; establishing which research institutions and individuals have the necessary technical and analytical skills and the motivation to carry out the required work; determining what funding would be required to carry out the proposed research and to establish a time-frame for accomplishing the work; and developing a plan for interinstitutional exchange of scientists and graduate students to ensure that the research program is truly collaborative, international and multidisciplinary. These objectives will contribute to the study of an (IAI) research priority, which is, to what extent climate variability in the two hemispheres is synchronous. The workshop will identify institutions and individuals and their relevant expertise to assign areas of responsibility for subsequent research. A priority list of sites where research should be initiated will also be prepared in order to build on existing knowledge or new areas for reconnaissance studies. Workshop participants will discuss what mechanisms currently exist or will be required to ensure that the proposed research will be carried out in the framework of full international collaboration.

Relationships Between Climate and Glacier Variations in Western North America
ATM 9530691
05/15/96; (ATM) $41,877, (OPP) $30,000; 11 months
University of Washington
Seattle, WA 98195
Howard Conway

This award will support a study designed to establish what climate information can be extracted from the glacial record on the west coast of North America. Glaciers contain a non-linear transformation of past meteorological conditions and a systematic comparison of the behavior of these glaciers has potential to reveal considerable new information about past climate in the region. The Aleutian Low in the north Pacific has a steering effect on storm tracks such that conditions are dry in Washington and wet in Alaska during years when the Pacific­North America index is positive; there is a negative correlation between the mass balance of Alaskan and Washington glaciers. This study will improve understanding of atmosphere­glacier processes. Although many high-resolution meteorological observations are needed to accurately model atmosphere­glacier processes over short (annual) time scales, two or three variables should be sufficient to explain behavior over longer (decadal) time scales. Sensitivity studies will explore glacier response to climate (both mass changes and subsequent dynamic response) through physical models of decreasing complexity, and establish the simplest workable model that accurately simulates behavior over decadal time scales.

Travel Support for U.S. Participants in Workshop on Glaciers, Ice Sheets, and Sea Level; Fjaerland, Norway; June 21­22, 1996
ATM 9612799
06/15/96; (OPP) $6,115, (ATM) $5,000; 11 months
University of Wisconsin­Madison
Madison, WI 53706-1490
Charles R. Bentley

The ice bodies of the world contain sufficient water to raise worldwide sea level by more than 70 m if melted completely. Glaciers and ice sheets might be a major source of water for the present-day rise in sea level, but the uncertainty is large. All glacial ice on the Earth must be considered in evaluating the contribution of changing ice masses to changing sea level. Furthermore, it is necessary to consider the history of past ice-sheet changes in order to interpret the present changes and predict those of the future. To evaluate all these factors in sea-level changes and to point the way towards research programs, a workshop will be held in Norway on the global interactions between glaciers, ice sheets and sea level. This award will make possible the participation by U.S. invitees in the workshop.

Study of Photoplastic Effect on Ice
DMR 9413362
12/15/94; (DMR) $60,000, (OPP) $25,000; 23 months
Dartmouth College
Hanover, NH 03755
Victor F. Petrenko

This project is co-funded between the Condensed Matter Physics and Polar Glaciology Programs. The project will investigate the characteristics and physical mechanisms of the photoplastic effect (PPE) in ice: pure and doped ice demonstrate significant and persistent hardening under the action of ultraviolet illumination. The fundamental mechanism of (PPE) in ice is not understood, and is of importance from a fundamental solid-state physics standpoint, as well as geophysical and environmental viewpoints. Both laboratory and field experiments will be conducted. Emphasis will be placed on microscopic processes which are studied by internal friction, dislocation currents, conductivity and photoconductivity, etching and replicating of dislocations emerging on the surface of the ice and spectroscopic study of photochemical products accumulating ice under illumination. The project also includes a modest theory component. The results are intended to determine the fundamental mechanism of the (PPE) in ice, and whether or not ultraviolet solar irradiation is essential in forming plastic properties of natural ice and snow.

Development of Laser-Based Resonance Ionization Spectroscopy Techniques for 81Kr and 85Kr Measurements in the Geosciences
EAR 9410695
09/01/94; (EAR) $71,848, (OPP) $10,000; 36 months
University of Tennessee­Knoxville
Knoxville, TN 37996-0140
Norbert Thonnard

This award provides funding for the development of a laser-based resonance ionization spectroscopy technique capable of measuring the isotopic abundances of noble gas constituents krypton-81 (81Kr) and krypton-85 (85Kr) in natural samples. The project is to be carried out in the Institute for Rare Isotope Measurements at the University of Tennessee. Accurate measurements of the radionuclei of 81Kr and 85Kr can contribute to a better understanding of processes in the environment, including dating of polar ice and very old groundwater, deep ocean circulation rates and modern water flow patterns. These isotopes have half-lives of 210,000 and 10.8 years, respectively, and are found in natural samples with isotopic abundances usually less than one part per trillion. Accurate analysis is a problem that has not yet been solved. The PI and colleagues on this project will develop a multi-step technique aimed at achieving an analytical procedure capable of measuring hundreds of environmentally significant samples per year.

Collaborative Research: Late Weichselian (Valdi) Glaciation and Deglaciation of Franz Josef Land, Russia
OPP 9222972
05/01/93; (OPP) $5,000; 48 months
Ohio State University Research Foundation
Columbus, OH 43210-1016
Steven L. Forman

This award is for support of a glacial geologic, stratigraphic, and geochronologic study of the limits and timing of Late Weichselian/Holocene glacial and deglacial events on Franz Josef Land, Russia. High-resolution satellite imagery will be used to identify study areas; radiocarbon dating of subfossils included in raised beaches of known elevation will provide information on the timing and rate of glacial-isostatic uplift; stratigraphic and sedimentological studies of glacial deposits will provide information on provenance; and integration of field data with isostatic and glaciological modeling will provide insight into glacial thickness, position of ice divides, domes and streams and possible response to sea-level rise. This study will provide new data on Holocene and Late Weichselian glacial geometry in the Russian Arctic, where little data currently exists.

Relation Between Water Input, Water Pressure, Surface Speed, and Basal Till Deformation, Storglaciaren
OPP 9224209
04/15/93; (OPP) $13,947; 54 months
University of Minnesota­Twin Cities
Minneapolis, MN 55415-1226
Roger Hooke

This award is for support of a project to study a small valley glacier in northern Sweden, Storglaciaren. The three objectives of this project are to: (1) develop an empirical relation between melt rates on the glacier surface and meteorological forcing; (2) establish a relation between subglacial water pressures and velocities at the glacier surface; and (3) measure strain rates, shear stresses and water pressures in the subglacial till in order to establish a constitutive relation for till deformation. A long-term goal of this work is to develop a model to predict glacier motion on diurnal-to-seasonal time scales.

Reconstruction of the Subarctic Climatic History and High-Resolution Dating of Glacier Fluctuations Using Tree-Ring Analysis at Yakutat and Icy Bays, Alaska
OPP 9321213
06/01/94; (OPP) $95,982; 36 months
State University of New York­Buffalo
Buffalo, NY 14260
Parker E. Calkin

This award is for a three-year study to investigate the subarctic climatic history as recorded largely in the tree-ring record, and to precisely date glacial fluctuations of ice tongues terminating in, and occurring at, the margins of the deep, 50-km long fjords of Yakutat and Icy Bays of southeastern coastal Alaska. Chronologies drawn from 500- to 900-year-old living trees cross-dated with logs of buried forests at multiple sites in each of the fjords will provide the main basis for climatic reconstruction over the last two millenia. Climatic and glacial series together are expected to yield the first sound basis for testing response of fjord glaciers to climate change.

Studies on the Mechanics of Columbia Glacier, Alaska, During its Rapid Retreat
OPP 9321556
06/15/94; (OPP) $83,343; 36 months
Ohio State University Research Foundation
Columbus, OH 43210-1016
Cornelis J. Van der Veen

This award is for support for a study on the mechanics of Columbia Glacier, Alaska, during its current rapid retreat. The extensive data set of surface elevations and velocities obtained from many repeat aerial photogrammetries of the glacier will be analyzed in order to identify the sites of, and magnitudes of mechanical controls on the lower part of the glacier. This data also will provide information to help determine whether the ongoing retreat is associated with a major change in flow style, and to test various calving relations at each phase of retreat of the ice front. The understanding of the controls of the collapse of the Columbia Glacier, obtained from these data, will be very helpful in understanding major collapses of other glaciers.

Geologic Test for Extent of Wisconsinian Glaciation on Southern Baffin Island, Arctic Canada, from Exposure Ages Determined by Radionuclides 26A1 and 10Be
OPP 9321733
06/01/94; (OPP) $6,222; 42 months
Bentley College
Waltham, MA 02154-4705
P. Thompson Davis

This award is for support for a project to refine the glacial chronology on southern Baffin Island by determining cosmogenic exposure ages of polished and striated bedrock surfaces and morainal boulders. In order to estimate the timing of deglaciation, the Beryllium-10 and Aluminum-26 in quartz separates from: (1) polished and striated bedrock surfaces on valley bottoms and along fjord sidewalls, and (2) boulders on nested sets of moraines will be measured. Preliminary results suggest that deglaciation in the Pangnirtung area of southern Baffin Island occurred around 7,500 years ago. This work will provide information to help resolve a long-standing controversy in Quaternary science involving the extent of ice sheets in the eastern Canadian Arctic during the late Wisconsinian.

An Ice Core Derived Multivariate Proxy Record of Holocene Climate Change from the Penny Ice Cap, Baffin Island, Canada
OPP 9322045
04/15/94; (OPP) $80,176; 42 months
University of New Hampshire
Durham, NH 03824
Gregory A. Zielinski

This award supports participation by a U.S. research team from the University of New Hampshire in an international collaborative effort to collect and study an approximately 500 m ice core from the Penny Ice Cap on Baffin Island, Canada. This project is a collaboration with the Geological Survey of Canada and Japan's National Institute of Polar Research. Field work includes study of snow pits and shallow cores in addition to collection and analysis of the main 500 m core. Laboratory work supported by this award includes analysis of major ions (sodium, ammonium, potassium, magnesium, calcium, chloride, nitrate and sulfate), insoluble microparticles and methanesulfonic acid. These data will be integrated with analytical data collected in Canada and Japan and the complete set of analyses will be used to construct a proxy record of climate and environmental conditions for Baffin Island for the Holocene. These data from the Penny Ice Cap will complement records from the Greenland Ice Sheet Project (GISP). Specifically, these data will provide information about climatic conditions at lower elevations that will allow a useful comparison to interpretations from the (GISP) cores.

Rheology of Basal Ice
OPP 9423422
04/01/95; (OPP) $78,291; 24 months
University of Minnesota­Twin Cities
Minneapolis, MN 55415-1226
Roger Hooke

This award supports a two-year study of the rheology of basal ice. The study has two principal parts: (1) measurements of the ice flow field around an artificial irregularity at the base of the glacier Engabreen in northern Norway; and (2) development of a theoretical (numerical) model that describes the three-dimensional flow field in basal ice. Tunnels through the bedrock beneath Engabreen will provide the unique setting and opportunity to directly measure the flow field in basal ice. The velocity field will be determined by using a video camera to monitor the position of markers in the ice. The numerical model will be based on an existing finite element code at the University of Minnesota, taking advantage of the facilities at the Minnesota Supercomputer Institute. Comparison between the model and the experimentally observed flow fields will permit an evaluation of various constitutive laws. Numerical values will be determined for the material constants in the models that give the best fit to the observed flow field.

Basal Morphology and Dynamics of a Temperate Surge-Type Glacier
OPP 9423477
07/01/95; (OPP) $234,033; 24 months
University of Alaska­Fairbanks
Fairbanks, AK 99775-0900
William D. Harrison

This award supports a three-year project to determine the morphology of the base of a surge-type glacier (Black Rapids Glacier, Alaska) using modern wireline drilling and sampling techniques, along with related measurements of basal water pressure, surface speed and other parameters. The project is an attempt to shed light, by direct observation, on the most important unsolved problem in glacier and ice-sheet dynamics-the role of basal motion and how it is affected by basal morphology. The role of bed morphology in glacier surging is of particular interest, because the restricted geographic occurrence of these glaciers may reflect necessary basal conditions. The drilling and sampling program proposed here should be able to recover continuous core of virtually any length, from the base of the clean ice, through any basal ice, sediments or combination of sediments and ice, and into the underlying bedrock. Although such sampling has been accomplished before in connection with mineral exploration, it would be the first scientific effort of its kind in a temperate glacier.

Assessment of Variations in the Snow Accumulation Rate in Northern Greenland
OPP 9423530
04/01/95; (OPP) $126,236; 24 months
University of Colorado­Boulder
Boulder, CO 80309-0019
Konrad Steffen

This award is for support for a three-year program to assess the variation in the snow accumulation rate in northern Greenland. Previous work has shown that isotope records from shallow ice cores can be used to identify interannual, and perhaps seasonal, cycles of snow temperature and accumulation. In order to assess seasonal and interannual variability, the isotope temperature record requires calibration from in situ meteorologic measurements. Ongoing remote sensing research appears to show that interannual trends in brightness temperature can be used as proxy data for annual accumulation, but this work requires calibration from ice core data in northern Greenland. Combining stable isotope measurements, remote sensing and surface energy balance data will allow an assessment of how interannual and seasonal processes affect the magnitude and variability of snow accumulation. Meteorologic data collection stati ons will be established and five shallow ice cores will be drilled in a 400-km2 area around each of two stations, one in northeastern and one in northwestern Greenland. Argos satellite links will provide data transmission capability from each remote site. Grain size and temperature profiles, sublimation and energy balance will be calculated using a one-dimensional energy and mass flux model.

Evaluation of a General Sliding Law by Flow Simulation, Haut Glacier d'Arolla, Switzerland
OPP 9496345
08/01/94; (OPP) $12,766; 36 months
Purdue University Research Foundation
West Lafayette, IN 47907
Jonathan M. Harbor

This award is for support for a project to use a finite element model for cross-sectional flow to constrain sliding and flow laws for the Haut Glacier d'Arolla (Switzerland). By varying sliding law exponents, the piezometric surface form and position, and the pattern of basal friction, it will be possible to constrain the range of conditions that yields velocity fields consistent with empirical data. This work takes advantage of a unique chance to test and refine the general sliding law, and an opportunity to explicitly examine spatial variations in sliding, in the context of detailed information on the temporal and spatial development of the glacier's hydrologic system. Although this work will be based on data collected in a mid-latitude alpine area, the results will be of direct relevance to polar glaciology because they can also be applied to glaciers with temperate (warm based) areas in polar regions.

Collaborative Research: Late Quaternary Glaciations of Northern Novaya Zemlya, Russia
OPP 9529293
07/15/96; (OPP) $88,222; 11 months
Ohio State University Research Foundation
Columbus, OH 43210-1016
Steven L. Forman
 
OPP 9529350
07/15/96; (OPP) $52,429; 11 months
University of Colorado­Boulder
Boulder, CO 80309-0019
Gifford H. Miller

The extent and timing of Pleistocene ice sheets over northern Eurasia remain unresolved. The views range from full coverage of the Barents and Kara Seas by a marine-based ice sheet to land-based ice cap systems on adjacent archipelagos. The heart of the divergence on the nature of last glaciation in northern Eurasia is uncertainty on ice-sheet thickness over Novaya Zemlya, Russia, and extension into Siberia. In collaboration with the Murmansk Institute of Marine Biology, we propose to initiate basic glacial-geologic, stratigraphic and geochronologic studies to provide new field data to independently evaluate the limits and timing of Weichselian glacial and deglacial events on Novaya Zemlya, Russia. Field research will focus on three field areas on northern Novaya Zemlya, where ice-free forelands contain abundant raised marine and glacial features. We plan to use the following approaches to decipher the record of Quaternary glaciations on Novaya Zemlya: (1) High-resolution (10-m pixels) SPOT satellite imagery will be used to evaluate large-scale sea-level, glacial erosional and depositional features (moraines) that may not readily be discernible in the field. (2) Documentation of the timing and rate of the glacial-isostatic response by radiocarbon dating of subfossils included in raised beaches of known elevation. (3) A study of the stratigraphy and sedimentology of superimposed Quaternary sediments in cliff sections. Particular attention will be given to the recognition of glacial damicts and unconformities, and the collection of micro- and macrofauna for paleoenvironmental assessment and chronological control. (4) Age control for the latest glacial/sea-level events will be derived from conventional and AMS radiocarbon dating of included marine subfossil and driftage. (5) Integration of field data with isostatic and glaciological modeling to provide insight into glacier thickness, position of ice divides, domes and streams and response to sea-level rise. Results from this study are important for evaluating if ice sheets on northern continental shelves responded synchronously, if the Barents, Kara and Norwegian Seas deglaciated prior to 14 ka ago, and the effect of Eurasian ice sheets on North Atlantic thermohaline circulation.

Pleistocene Sea-Level and Glacial Fluctuations, Coastal Ahklun Mountains, Southwest Alaska
OPP 9529940
06/15/96; (OPP) $69,165; 11 months
Utah State University
Logan, UT 84322
Darrell Kaufman

Recent work in the south part of the west coast of Alaska (eastern Bristol Bay, 59°N) demonstrates that glaciers experienced extensive advances during the late Pleistocene. In northwestern Alaska (Seward Peninsula, 65°N, and western Brooks Range, 67°N), on the other hand, early Wisconsin glaciers were restricted to the highest mountain valleys and occupied an area approximately an order of magnitude less extensive than during middle and early Pleistocene advances. The most recent major advance of glacier ice to the coast in southwestern Alaska was at least 300,000 years younger than the last advance of ice to the coast in northwestern Alaska. To understand the cause and significance of this apparent glacial-geologic and paleoclimatological incongruity, the following must be addressed: (1) Where and over what distance along the coast between eastern Bristol Bay and Seward Peninsula does the crossover between late Pleistocene glacial maxima and middle Pleistocene maxima occur? (2) To what extent do valley hypsometries control the extent of ice from the different source areas? (3) What does the geographic distribution of late-Wisconsin and pre-late-Wisconsin ice imply about equilibrium line altitude (ELA) lowering and equilibrium line altitude (ELA) gradients, and consequently, moisture sources and other climate variables? Solving these questions will require extensive field, aerial photographic and geochronologic research in the only glaciated region between eastern Bristol Bay and Seward Peninsula-the Ahklun Mountains. It will depend on a multidisciplinary effort to obtain numerical-age control on the deposits. State-of-the-art geochronologic and sedimentologic techniques will be applied to reconstruct the spatial and temporal pattern of Pleistocene sea-level and glacier fluctuations. This work will improve the understanding of the paleoclimatological controls of glaciation across western Alaska and their relation to the global climate system; it also should enable us to address whether or not glaciation in southwestern Alaska is synchronous with Northern Hemispheric ice-sheet fluctuations, or whether or not major glaciations here precedes ice build-up at lower latitude.

Tritium in Basal Ice and Debris Bands: Demonstration of Freeze-On from Subglacial Waters
OPP 9530757
07/15/96; (OPP) $197,150; 23 months
Lehigh University
Bethlehem, PA 18015-3005
Edward B. Evenson

The objectives of the proposed research are to determine the rates of subglacial ice accretion, identify the genesis of englacial debris bands and assess the generality of freeze-on mechanisms. Recent research by the authors demonstrates that debris-rich basal ice at th e Matanuska Glacier in south-central Alaska forms by basal freeze-on in an open hydrologic system. Evidence includes: (1) tritium-rich basal ice; (2) summer melt-season ice growth in subglacially-fed, high-pressure discharge vents; and (3) measurements of sub-zero water temperatures. Subglacial water flowing towards the terminus supercools when the pressure-melting point rises faster than the temperature increases. During periods of high discharge, supercooling occurs where the slope of the bed is steeper and in the opposite direction of the slope of the glacier surface. Tritium analysis provides a "fingerprint" of ice which formed since 1952. Elevated concentrations of tritium in basal ice indicate post-1952 freeze-on from atmospherically-derived waters. High-resolution analysis of tritium from multiple basal sections at the Matanuska Glacier will provide data necessary to calculate subglacial accretion rates and to estimate the relative contributions of different water sources to the subglacial drainage system. A record of tritium concentrations in precipitation in this region from 1958 to 1993 provides an input function to which the tritium profiles in basal ice can be correlated. In addition, tritium in samples obtained across englacial debris bands at the Matanuska Glacier will provide information on the genesis of these ubiquitous and controversial features. Interpretations of Heinrich events, estimates of glacial debris flux and models of glacier sliding all require knowledge or assumptions of subglacial conditions and mechanisms of debris entrainment. The information gained from this research will increase our understanding of subglacial processes and will provide critical constraints to numerical models of glacier flow and debris transport in the glacial system.

Global Glacier Mass Balance Synthesis
OPP 9530782
09/01/96; (OPP) $84,597; 12 months
University of Colorado­Boulder
Boulder, CO 80309-0019
Mark F. Meier

A global synthesis of glacier mass balance data is proposed, which will include an evaluation and digitization of measured mass balance data. The mass balance data set will include three databases: (1) annual specific mass balances of all measured mountain and subpolar glaciers; (2) annual accumulation (or winter balance) and annual ablation (or summer balance); and (3) winter, summer and annual mass balance gradients with altitude. These data will be analyzed in several ways: statistical spatio-temporal analyses of individual glaciers, mountain ranges and countries, both hemispheric and global; analyses of annual fluctuations and determination of long-term mass-balance trends; and analyses of mass balance gradient changes. The main tasks: (1) assemble and check the annual specific mass balance data of all measured glaciers since 1945; (2) determine the contribution of glacier changes to sea level (e.g., how much do different glacier regions contribute to sea-level change?); (3) estimate the variability of winter and summer balances (or annual accumulation and ablation) and their impact on annual mass balances in different geographical locations; (4) determine the main causes for mass balance changes in different mountain regions; and (5) analyze mass balance gradients (activity indices) and their changes in connection with climate change. The end products of this research will include three mass balance data sets which will be produced at (INSTAAR) in a form accessible by the community, and in a data report.

Glaciological Interpretation of Changes in Radar Reflection Characteristics from Glaciers
OPP 9530827
07/01/96; (OPP) $37,540; 12 months
University of Washington
Seattle, WA 98195
Charles F. Raymond

The speed of glaciers and ice sheets can be affected by hydraulic conditions at their beds. Examples are the dramatic fast-motion of ice streams and glacier surges or the more modest seasonal variations in speed that are common in temperate glaciers. The connection between glacier speed and hydraulic conditions at the bed has been established through borehole and glacial discharge observations. However, these observations yield only very limited spatial coverage (in the case of boreholes) or resolution (in the case of stream discharges). Radio echo-sounding (RES) has been used extensively to map the thickness and structure of many glaciers and ice sheets. The PI recently used (RES) to monitor the spatial and temporal reflection changes within a temperate glacier (Black Rapids Glacier, Alaska) and across a relict ice stream margin in Antarctica. Results from Black Rapids Glacier show distinct temporal changes in (RES) return characteristics during the early part of the melt season when the speed of the glacier increased significantly. Results from Antarctica show a large spatial change in (RES) return characteristics; the reflection strength of the bed changed by about 300% in a traverse across the relict margin. Interpretation of the evolving physical conditions at the bed is complicated because some of the observed changes in (RES) returns from the bed may be caused by changes at the surface and/or within the interior of the ice. The PI proposes to determine the changes in reflection characteristics of the bed by using multivariate analysis to remove the effects of transmission through the surface and propagation within the ice. Models of reflection from layered dielectric media will be used to investigate relationships between the changes in reflection coefficient and changes in basal conditions, such as the thickness and electrical conductivity of water at the bed. The objective is to use the (RES) records to gain understanding about physical conditions at the bed of glaciers and ice sheets.

Collaborative Research: Direct Measurement of the in situ Stress Tensor at Depth in Glacier Ice
OPP 9531450
07/15/96; (OPP) $128,881; 11 months
University of Colorado­Boulder
Boulder, CO 80309-0019
W. Tad Pfeffer
 
OPP 9531565
08/01/96; (OPP) $62,048; 12 months
University of Wyoming
Laramie, WY 82071-3434
Neil F. Humphrey

A technique for direct, in situ measurement of the stress tensor in deep glacier ice will be developed by adapting methods presently in use in rock mechanics for the measurement of in situ stress in visco-elastic/plastic materials. Direct stress and deformation measurements will be combined. This will provide two critical properties near the bed of a glacier experiencing fairly complex sliding behavior. For the first time, independent observations of the full stress tensor and the full strain rate tensor in glacier ice will be obtained. The determination of the spatial and temporal character of coupling between glacier ice and the glacier bed is necessary for understanding the dynamics of virtually all ice masses of current interest. Variations in basal and marginal tractions are critical controlling factors in polar ice streams, calving and surging glaciers. The behavior of ice sheets, as well as the stratigraphic interpretation of cores taken from ice sheets, depend on an understanding of the patterns of coupling at the bed and the velocity fields that arise in the ice as a consequence.

Ice/Rad ar and Satellite Remote-Sensing Studies of Glaciers and Ice Sheets­II
OPP 9531501 (Arctic Funding Component)
04/15/96; (OPP) $15,075; 11 months
St. Olaf College
Northfield, MN 55057
Robert W. Jacobel

This project is for continued funding of the Research Experiences for Undergraduates (REU) Site at St. Olaf College and South Cascade Glacier, West Antarctic. Since 1987, with support from the NSF, the St. Olaf ice radar has been part of the effort to understand the dynamics of the West Antarctic ice sheet. The St. Olaf contribution to this project has been the development and deployment of a ground-based radar system used in studies of several of the fast ice streams which drain into the Ross Ice Shelf. Through the current (REU) award, the group has more recently become involved in the use of satellite imagery for obtaining ice velocities-a complementary tool to the radar also used for understanding ice dynamics. At the same time, St. Olaf has carried out an active research program on South Cascade Glacier in collaboration with scientists at the U.S. Geological Survey. In addition to serving as a testing and development site for the Antarctic radar system, this glacier has been the focus of an intensive effort to investigate the problem of englacial and subglacial drainage and hydrology. Studies on South Cascade Glacier also provide an accessible site for students to experience glaciological science in the field, and to plan and carry out experiments of their own design, similar to those done in the polar regions. This proposal will enable undergraduate students to participate in the data reduction and analysis phase of radar and ice dynamical studies being carried out on Siple Dome, Antarctica. It also will fund a complementary study of ice velocities in this area using satellite imagery to answer questions about the transitory nature of the ice streams surrounding the dome. The proposal supports continued field work in South Cascade Glacier to study problems of glacial hydrology and further developments of the radar system.

Radar Array Suppression of Englacial Coherent Noise in Probing Temperate Glaciers
OPP 9531579
09/01/96; (OPP) $58,273; 24 months
Penn State University­University Park
University Park, PA 16802-1503
Roy J. Greenfield
 
High Frequency Radar Array Characterization of Temperate Glacier Hydrology
OPP 9531800
09/01/96; (OPP) $58,208; 24 months
U.S. Army Cold Regions Research and Engineering Laboratory
Hanover, NH 03755-1290
Mark L. Moran

The ultimate scientific objective of this study is to investigate a new high-frequency radar array technology for characterizing temperate glaciers by mapping bed topography, basal ice hydrologic features, thickness and distribution of saturated tills and deep englacial drainage channels. It is widely acknowledged that presently there are no effective direct, or remote, methods capable of delineating these structures. Radar methods fail because of the intrinsic high noise properties of temperate glaciers. Modern radar instruments have overcome random noise and antenna noise problems. The current limitation on radar is noise resulting from subsurface water inclusions, which impose a 10-mHz upper frequency limitation on conventional temperate glacier surveying methods. A radar survey method utilizing array processing can significantly suppress noise from water-filled scattering inclusions. Numerical models and time domain data processing algorithms will be developed to guide the array design, performance analysis and interpretation procedures. In addition, a physical scale model of a temperate glacier will be used to collect radar data in the millimeter wave frequency (30 gHz) range. The physical model results will be used to verify numerical and theoretical array processing results and further refine the approach. A field experiment will be carried out on the shallow (100­200 m), readily accessible Gulkana Glacier, Alaska. This field experiment will include conventional radar and radar array data collection methods with 100-mHz antennas. In the field operations they will be specifically interested in demonstrating the improved depth of penetration using the array method as compared to the conventional technique. The immediate glaciologic benefits will be an accurate picture of how near-surface englacial and basal ice water channels are interconnected and oriented on a small, but interesting temperate glacier. The extended benefit will be the development of a practical method for sounding much deeper temperate glaciers. For example, on very deep (1000 m) temperate glaciers they believe the high-frequency radar array could operate at a center frequency around 30 mHz. In this band, multiple radar array stations, or a towed array, would have the potential to define, characterize and spatially map meter scale englacial and basal ice hydrologic features, as well as ice bed topography. This is particularly relevant since the depth and bottom topography of almost all large subpolar ice fields are unknown. In addition, a high-resolution deep penetration radar capability applied to large ice masses would help answer questions about steady flow and surge mechanisms, basal freeze, and sediment transport. The radar array technique will also be applicable to Antarctic glaciers.

Operation and Maintenance of the U.S. National Ice Core Laboratory
OPP 9634659
03/01/96; (OPP) $47,101; 69 months
U.S. Geological Survey
Reston, VA 22092
Joan J. Fitzpatrick

This award is for support for the operations and maintenance of the U.S. National Ice Core Laboratory (NICL), a government-owned facility for storing, curating and studying ice cores recovered from the ice-covered regions of the world. (NICL) provides NSF- and U.S. Geological Survey-funded investigators with the capability to conduct examinations and measurements of ice cores while preserving the integrity of these cores in a safeguarded environment. (NICL) fosters the utilization of these cores for scientific research by handling inquiries from scientists interested in obtaining samples of ice cores, by making inventory listings easily available through electronic distribution, by acting as an information resource to the scientific community and by improving current technologies for ice core analysis in accordance with the needs and requirements of their client base. (NICL) is located at the Denver Federal Center in Lakewood, Colorado, and is housed administratively within the USGS Office of the Central Regional Geologist, Geologic Division.