bluuebunny/crossref_metadata_2025 huggingface dataset:
Featuring Historical Textbooks to Build Knowledge of University History
Authors: Rathe Bette , Lowell Kay
Published: September 2017

Undergraduate students at a teacher education institution, the University of Northern Colorado, are the target audience for an exhibit of a reading series from the Libraries’ Archival Services collections. The display highlights an important era in the university’s history involving four faculty members: Paul McKee, M. Lucile Harrison, Annie McCowen, and Elizabeth Lehr. These professors developed an innovative approach to early reading instruction that was incorporated into their reading textbook series during a time of uniformity in reading textbooks. The rationale for the display was based on research about the Reading for Meaning series discussed in this article.
Two Profiles: The ETS Test Collection
Authors: Rosen Pamela
Published: September 2017

The ETS Test Collection is an extensive library of tests for use by qualified professionals such as educators and psychologists. [...]
Librarian as Professor: A Dynamic New Role Model
Authors: Fallahay Loesch Martha
Published: September 2017

The 20th century information explosion provided widespread technological innovation and ease of access to information, and due to the 21st century emphasis on digital collections and electronic resources, libraries around the world are facing an uncertain future. This naturally causes librarians to re-evaluate their professional role, but perhaps academic librarians are best prepared for the future due to their co-existing role as professors. Essentially they have always been teaching, but now they must conquer the disparaging image and status treatment to which they have been subjected and evolve their profession by joining their teaching faculty colleagues in classrooms on college and university campuses worldwide.
Embedded Librarianship is a Winning Proposition
Authors: Jacobs Warren N.
Published: September 2017

A reference/instruction librarian used targeted outreach to furnish library services to faculty and students while assigned to work in the College of Education during a library renovation project. Due to the success of this temporary assignment, the author has subsequently maintained regular office hours in the College to provide research consultations for faculty and students, collaborate on collection development, and continue outreach efforts resulting in increased requests for research assistance and course-integrated information literacy instruction. The benefits and challenges of embedded librarianship in an academic department are also discussed.
The Curriculum Material Center’s Vital Link to Play and Learning: What’s the Connection?
Authors: Madray Amrita , Catalano Amy
Published: September 2017

Many educational theorists who study child development concur that the importance of play related materials in schools, homes and libraries is vital to the concept of play and learning. As academic librarians responsible for information literacy, and as the education liaison for the management and collection development of the instructional component in the Curriculum Materials Center, the authors of this paper will explore valuable connections between children‘s play and learning. Further, they will discuss how that association affects a child‘s cognitive development as seen through the curriculum materials and the educational support for teachers who work closely with students.
Censorship or Selection? Academic Library Holdings Of the Top Ten Most Challenged Books of 2007
Authors: Best Rickey
Published: September 2017

Academic libraries often serve as the protectors of challenged books. Pressure on public libraries to remove controversial works can and often does result in the restriction of access or removal of the work from those libraries shelves. Academic libraries, however, operate with a stronger sense of academic and intellectual freedom. To analyze how well academic libraries do in acquiring and making available books which appear on the American Library Association‘s Challenged Books list, the list for 2007 was analyzed in WorldCat to determine the number and overall percentage of academic libraries holding the titles. Overall, 29.94% of the libraries holding challenged books were academic libraries.
The Role of Multicultural Information in Experiential Learning
Authors: Shen Lan
Published: September 2017

This paper is based on the author’s empirical experience in assisting cultural immersion programs through developing multicultural collections, promoting diversity resources, and creating a supportive information environment for faculty and students. After summarizing the significance, goals, learning objectives, and program models of cultural immersion, this paper discusses the principles of selecting multicultural materials, cultural immersion information, and practical tips on designing and maintaining web-based sources. This paper also addresses the issues of developing an effective mechanism to build collaboration between librarians and faculty members with respect to cultural immersion curricula and to create an open information environment for disseminating multicultural resources for experiential learning courses.
From the Classroom to the Boardroom: The Impact of Information Literacy Instruction on Workplace Research Skills
Authors: Travis Tiffini A.
Published: September 2017

Since the wide-scale adoption of the ACRL Information Literacy Standards (2000), there have been numerous students who have graduated from universities that have formal library instruction programs. Currently there has been very little assessment of their post-graduate research skills or what role information literacy plays on workplace performance. [...]
Editorial
Authors: Snider Jacqueline
Published: September 2017

Whenever I can, I attend Humanities lectures— such as the one given by Leah Price at the University of Iowa, or sessions at conferences that come very close to the world of library and information science. From what I am seeing, academics from English, comparative literature, linguistics, and sociology are knocking at ourdoor. [...]
Analyzing the Determinants of Cash Holdings of Small and Medium-Sized Entities in Nigeria
Authors: Tsagem Muhammad Musa , Aripin Norhani , Ishak Rokiah
Published: September 2017

Purpose: This paper aims to report the results of an empirical investigation on the determinants of the cash holdings for small and medium-sized entities. The paper considers the different explanatory factors of SMEs cash holdings for a sample of Nigerian SMEs. SMEs are springboard of the Nigerian economy contributing to gross domestic product, employment generation and industrialization.
Methodology: the study employed panel data regression analysis using secondary data on a sample of 311 Nigerian SMEs for the period 2007 - 2013.  
Result: The finding which is robust of endogeneity shows statistically significant association between cash conversion cycle, account receivables period, return on assets and board size with SMEs cash holdings. Also found a significant relationship between cash holdings with firm size, leverage, growth opportunities and firm age. 
Implication: Thus, the result of the study indicates that Nigerian SMEs with shorter cash conversion cycle and low growth opportunities hold more cash.  Similarly, SMEs with small board of directors accumulate large cash balance.  Further, SMEs with higher profitability keep large cash balance.  This study contributes to existing literature on the determinants of SMEs cash holdings more specifically in developing economies.  However, this study is limited to non-financial and non-service SMEs.  Future study should extend the investigation to financial and services firms. Similarly the structure of the paper and scope of further study may be extended to include the effects of more corporate governance mechanisms.
Challenges in Marketing of Islamic Banking Products in Malaysia
Authors: Rasheed Rabia , Chauhan Ajay
Published: September 2017

The history of banking is as old as Islam but the histoy of Islamic banking is only half a century old. It is agreed that Islamic banking started with a saving bank based on profit sharing in Mit Ghamr, Egypt in 1963. But, the first proper Islamic bank is deemed to be the Nasser Social Bank in 1971, again in Egypt. In 2013, after 50 years, there are about 400 Islamic banks and institutions in 53 countries with a fund based of USD 992 billion and asset based of USD 1.3 trillion. When Islamic banking started, Malaysia was busy with independence. Therefore, the start of Islamic banking in Malaysia was delayed by two decades. Malaysia passed Islamic banking Act in 1983 to start Bank Islam Malaysia Berhad with a capital based RM 80 million. The next three decades saw a tremendous growth. By 2013, there were 16 domestic and 5 international Islamic banks in Malaysia with an asset based of RM 442 billion, which does not include 15 Takaful operators. In spite of this tremendous growth, Islamic banking does not compare with conventional banking in terms of volume and acceptability. There have been studies which show that while 80% of the banking customers in Malaysia are aware of Islamic banking, but were not aware of Islamic banking products like Ijarah, Murabahah, etc. This conceptual paper brings out the challenges of marketing Islamic banking products in Malaysia and traces the roots of the problem to the lack of customer centricity.
Quest for Alternative Sociological Perspectives on Corporate Social and Environmental Reporting
Authors: Mahmood Zeeshan , Ahmad Zubair
Published: September 2017

Objective: The purpose of this paper is to review existing dominant theoretical perspectives used in corporate social and environmental accounting research, identify their limitations and to suggest some alternative theoretical perspectives for further research.

Methodology: In order to identify relevant research papers, on the use of different theoretical perspectives on corporate social and environmental accounting research, published in academic journals, different keywords were searched in google scholar. Research papers were then shortlisted according to their relevance to the topic.

The results: Among all theoretical frameworks, there is a great variety but accounting researchers remained selective in heir use of the theory and some other aspects of the theory remained unexplored. Apart from this narrow application, repeated application of same theories, especially legitimacy and stakeholder theory) provide very little additional insights.

Implication:

The dominant theoretical perspectives on CSER do not fully capture the complexity of the phenomenon. This situation demands researchers to explore alternative theoretical perspectives for better and insightful research. The main contribution of this paper is that it suggests the theory of realistic evaluation (RE) and the institutional logics perspective (ILP) as alternative sociological perspectives. This paper invites future researchers to apply these theoretical frameworks and to explore their usefulness.
Effect of Corporate Governance and Financial Leverage on Market value Added in Pakistan
Authors: Shahid Muhammad Sadiq , Khakwani Maria Shams , Hamza Ali
Published: September 2017

This paper examines the impact of corporate governance rules and regulations and financial leverage on the market value added in Pakistan. Market value added (MVA) is our dependent variable and corporate governance and financial leverage are our independent variables and examine their combined effect on the market value added. This study will help the Pakistani firms who are going to lever their firms and going to practicing the corporate governance rules and regulations. For this purpose we have taken the listed non-financial companies of Pakistan from 2006-2015 because they are actively practicing the corporate governance rules and regulations. The results indicate that the proxy variable of corporate governance which is board size also have the significant and negative impact on the MVA in Pakistan. Interest coverage ratio indicates that if the firm's ability to pay its interest expenses increases as results MVA also increases. Debt ratio is the proxy variable of financial leverage which is our next independent variable. By the help of our regression model we concluded that Debt also have the positive significant effect on the market value added on the firms in Pakistan. It means if a firm wants to increase their market value they should go for the debt instead of equity. Debt will help firms in Pakistan to increase their market value.
The Analysis of the Validity of Capital Asset Pricing Model: Evidence from Pakistan Stock Exchange
Authors: Akhtar Adeel , Malik Muhammad Shaukat , Nusrat Imran , Bakhsh Allah
Published: September 2017

The aim of this study was to find evidence for the implementation of capital asset pricing model (CAPM) on companies listed at Pakistan StockExchange before, during and after financial crisis. The data of 50 companies were collected ranging from various sectors of Pakistan stockexchange. Data were divided into 3 different groups: year 2005-2007, 2008-2010 and 2011-2013. Regression analysis was conducted for testingthe hypotheses by taking Pakistan stock exchange 100 index as independent variable and individual stocks return as dependent variable.Three different levels of significance have been used: significance at 1%, significance at 5%, and significance at 10%. The results suggested that inPakistan different business organizations due to narrow scope of business are relatively less diversified and have relatively high flexibility ofresponding unexpected and uncertain events, influencing overall market performance. Similarly, large number of companies, specifically duringperiod of financial crisis, are affected and influenced by numerous risk factors. It was concluded that fair prices of stock cannot be determinedwith the help of CAPM in Pakistan.
Influence of Creative Accounting on Reliability and Objectivity of Financial Reporting (Factors Responsible For Adoption of Creative Accounting Practices in Pakistan).
Authors: Shahid Maria
Published: September 2017

Purpose: Intellectual modifications (creative accounting) in financial reports to make them attractive are very emerging and vastly accepted practices around the globe. But these practices are deceiving and unethical. This study aims to explore the factors encourage the adoption of  creative accounting practices like agency problem, corporate governance, company's ethical value, company's future orientation etc. as well as how these practices affect the reliability and objectivity of financial reporting.

Methodology: This research is an empirical research and data is collected from accounting and management professionals of manufacturing industry of Punjab via structured questionnaire. Convenient sampling technique used to select sample size and SPSS software used for data analysis.

Findings: Results of this research explored the positive association between agency problem and creative accounting while corporate governance, company's ethical value, company's future orientation have negative impact on creative accounting. It is also verified that creative accounting has significant negative impact on reliability as well as objectivity of financial reporting.

Implications: Results of this study will assist the company's management how to control adverse influence of these manipulative activities on reliability and objectivity of financial reports as well as provide literacy to investors to be aware of such extensively using speculative activities.

Limitations: Limitations of this study are that it is only considering few factors as well as manufacturing industry of Punjab.
Late Neogene Sirius Group strata in Reedy Valley, Antarctica: a multiple-resolution record of climate, ice-sheet and sea-level events
Authors: Wilson Gary S. , Harwood David M. , Askin Rosemary A. , Levy Richard H.
Published: September 2017

Late Neogene Sirius Group strata from Tillite Spur and Quartz Hills in the Reedy Glacier area, Antarctica, demonstrate the variability in Sirius Group facies and contrasts Sirius Group strata deposited at high and low paleo-elevation, respectively. The Tillite Spur and Quartz Hills Formations (Pliocene) are formally defined here.The Tillite Spur Formation type section crops out on the edge of the Wisconsin Plateau overlooking Tillite Spur. It comprises 32m of alternating coarse gray conglomerate and muddy olive-brown diamictites. The Quartz Hills Formation type section crops out above the western margin of Reedy Glacier in a pre-existing cirque towards the southern end of the Quartz Hills. It comprises c.100m of alternating massive diamictites and rhythmically interbedded sandstone and laminated mudstones which were deposited close to sea level and subsequently rapidly uplifted (>500 m Myr−1) to their present elevation at c. 1500 m. Three orders of paleoclimatic variability are recorded in the Sirius Group strata from Reedy Valley: (1) recycled marine microfloras in glacial diamictites indicate intervals of marine incursion into the Antarctic cratonic interior co-occurring with reductions in the East Antarctic ice sheet; (2) an advancing and retreating paleo-Reedy Glacier deposited a glacial/interglacial sequence alternating on a 10-100 kyr scale; 3) Centimeter and millimeter stratification in strata of the Quartz Hills Formation record annual kyr scale variability.
Modelling the evolution of subglacial tunnels due to varying water input
Authors: Cutler Paul M.
Published: September 2017

The time evolution of a subglacial tunnel cross-section is examined usine a two-dimensional finite-element ice-flow model coupled to an idealized drainage system. Simulations are driven by physically based calculations of surface water-input variations at Slorgiaciaren, Sweden. Highlights of the model are its ability to handle unsteady conditions and irregular tunnel shapes. Agreement between modelled water pressure and borehole water levels is good. The following conclusions are reached: (i) Tunnels adapt to fluctuating inflow on time-scales of days. Storms, during which effective pressure ranges from 0 to 0.9 MPa, cause significant adjustments but daily fluctuations due solely to melt-water inflow are minor, (ii) Open-channel flow may become commonplace late in the ablation season, (iii) Initial tunnel shape influences subsequent tunnel evolution and seasonal water-pressure variation. Over the course of a summer, tunnels retain some of their initial shape, though in all experiments the width-to-height ratio increased with time, (iv) Tunnel contraction forms broad low tunnels. However, (v) given two tunnels of equal initial area, the higher narrower one expands more rapidly. Thus, more semi-circular tunnels may capture How from broader neighbours early in the summer.
Analysis of the 1993-95 Bering Glacier (Alaska) surge using differential SAR interferometry
Authors: Fatland Dennis R. , Lingle Craig S.
Published: September 2017

Differential spaceborne radar interferometry observations of West Bagley Icefield are used to measure surface velocity and topography. Bagley Icefield is the accumulation area fur Bering Glacier which surged in two phases from spring 1993 through summer 1905. The observations presented are based on data collected during the winter of 1992, prior to the surge, and during winter 1994 while the surge was in full progress. Both observation intervals correspond to 3 day repeat orbit phases of the ERS-I C-band SAR. This paper gives an overview of the algorithms used to derive surface-velocity vector fields and topography for valley glaciers from SAR images. The resulting high-resolution velocity data clearly show West Bagley Icefield accelerating from its quiescent pre-surge velocity by a factor of 2.7 in response to the Bering Glacier surge. Persistence of lnterfero-metric phase coherence and the relatively moderate degree of acceleration on the western arm of Bagley Icefield suggest that the velocity increase may have been caused by increased longitudinal stress gradients resulting from coupling to the surging main trunk of Bering Glacier.
Glaciohydraulic supercooling: a freeze-on mechanism to create stratified, debris-rich basal ice: II. Theory
Authors: Alley Richard B. , Lawson Daniel E. , Evenson Edward B. , Strasser Jeffrey C. , Larson Grahame J.
Published: September 2017

Simple theory supports field observations (Lawson and others, 1998 that subGlaciol water flow out of overdeepenings can cause accretion of layered, debris-bearing ice to the bases of glaciers. The large meltwater flux into a temperate glacier at the onset of summer melting can cause rapid water flow through expanded basal cavities or other flow paths. If that flow ascends a sufficiently steep slope out of an overdeepèning, the water will supercool as the pressure-melting point rises, and basal-ice accretion will occur. Diurnal, occasional or annual fluctuations in water discharge will cause variations in accretion rate, debris content of accreted ice or subsequent diagenesis, producing layers. Under appropriate conditions, net accretion of debris-bearing basal ice will allow debris fluxes that are significant in the glacier sediment budget.
Errors in daily ablation measurements in northern Greenland, 1993-94, and their implications for glacier climate studies
Authors: Braithwaite Roger J. , Konzelmann Thomas , Marty Christoph , Olesen Ole B.
Published: September 2017

Ablation climate studies were made at two locations in northern Greenland in the summers of 1993 and 1994, respectively. Daily ablation was measured at ten stakes within a small area, and the data were compared with each other to detect gross errors. For example, high standard deviations for data taken on the same day, or low correlations between data series at different stakes, indicate erroneous data. After discarding data for one stake in 1993 and two stakes in 1994, random errors in daily ablation data for individual stakes are ± 5 kg m 2 d−1, which is further reduced to only about db 2 kg m−2d−1 by averaging over eight or nine stakes. Random errors in calculated energy balances using the present ablation data are much lower than found in earlier stuthes in West Greenland where ablation was only measured on three stakes without any attempt to detect gross errors. Aside from day-to-day errors, there are ±10% differences in mean ablation at different stakes, which are probably caused by small-scale variations in surface albedo. Such interstate differences give a ± 10% uncertainty in positive degree-day factors, which are 9.8 ± 0.9 and 5.9 ± 0.6 kg m 2 d −1 deg −1 for the two sites.
Migration of the Siple Dome ice divide, West Antarctica
Authors: Nereson N. A. , Raymond C. F. , Waddington E. D. , Jacobel R. W.
Published: September 2017

The non-linearity of the ice-flow law or a local accumulation low over an ice divide can cause isochrones (internal layers) to be shallower under the divide relative to the flanks, forming a “divide bump” in the internal layer pattern. This divide signature is analyzed using ice-flow models and inverse techniques to detect and quantify motion of the Siple Dome ice divide, West Antarctica. The principal feature indicating that migration has occurred is a distinct tilt of the axis of the peaks of the warped internal layers beneath the divide. The calculated migration rate is 0.05-0.50 m a−1 toward Ice Stream D and depends slightly on whether the divide bump is caused by the non-linearity of ice flow or by a local accumulation low. Our calculations also suggest a strong south-north accumulation gradient of 5-10 x 10−6 a−1 in a narrow zone north of the divide. A consequence of divide migration is that pre-Holocene ice is thickest about 0.5 km south of the present divide position. Divide motion indicates that non-steady processes, possibly associated with activity of the bounding ice streams, are affecting the geometry of Siple Dome. The migration rate is sufficiently slow that the divide bump is maintained in the internal layer pattern at all observable depths. This suggests that major asynchronous changes in the elevation or position of the bounding ice streams are unlikely over at least the past 103-104 years.
Thickening of the western part of the Greenland ice sheet
Authors: Thomas Robert H. , Csathó Beáta M. , Gogineni Sivaprasad , Jezek Kenneth C. , Kuivinen Karl
Published: September 2017

NASA's Program for Arctic Regional Climate Assessment (PARCA) includes measurements of ice velocity and ice thickness along the 2000 m elevation contour line in the western part of the ice sheet. Here we use these measurements together with published estimates of snow-accumulation rates to infer die mass balance, or rate of thickening/thinning, of the ice-sheet catchment area inland from the velocity traverse. Within the accuracy to which we know snow-accumulation rates, the entire area is in balance, but localized regions inland from Upernavik Isstrom and Jakobshavn Isbra both appear to be thickening by about 10 cm a-1.
An improved coherent radar depth sounder
Authors: Gogineni S. , Chuah T. , Allen C. , Jezek K. , Moore R. K.
Published: September 2017

The University of Kansas developed a coherent radar depth sounder during the 1980s. This system was originally developed for glacial ice-thickness measurements in the -Antarctic. During the field tests in the Antarctic and Greenland, we found the system performance to be less than optimum. The field tests in Greenland were performed in 1993, as a part of the NASA Program for Arctic Climate Assessment (PARCA). We redesigned and rebuilt this system to improve the performance.

The radar uses pulse compression and coherent signal processing to obtain high sensitivity and fine along-track resolution. It operates at a center frequency of 150 MHz with a radio frequency bandwidth of about 17 MHz., which gives a range resolution of about 5m in ice. We have been operating it from a NASA P-3 aircraft for collecting ice-thickness data in conjunction with laser surface-elevation measurements over the Greenland ice sheet during the last 4years. We have demonstrated that this radar can measure the thickness of more than 3 km of cold ice and can obtain ice-thickness information over outlet glaciers and ice margins.

In this paper we provide a brief survey of radar sounding of glacial ice, followed by a description of the system and subsystem design and performance. We also show sample results from the held experiments over the Greenland ice sheet and its outlet glaciers.
Temperature history and accumulation timing for the snowpack at GISP2, central Greenland
Authors: Shuman C. A. , Alley R. B. , Fahnestock M. A. , Bindschadler R. A. , White J. W. C. , Winterle J. , Mconnell J. R.
Published: September 2017

Previous research has documented a close association between high-resolution snow-pit profiles of hydrogen and oxygen stable-isotope ratios and multi-year Special Sensor Microwave/lmager (SSM/I) 37 GHz brightness temperature data in central Greenland. Comparison of the SSM/I data to profiles obtained during the 1989-91 field seasons indicated that δD and δ18O data from the near-surface snow at the Greenland summit are a reliable, high-resolution temperature proxy. To test this new technique further, additional stable-isotope data were obtained from a 2 m snow pit constructed during late-June 1995 near the GISP2 site.

This new profile, supported by pit stratigraphy and chemistry data, confirms the utility of comparing stable-isotope records with SSM/I brightness temperatures. The sub-annual variation of the δD record at the GISP2 site was determined using 15 match points, from approximately December 1991 through June 1995 and was guided in part by time-constrained hoar layers. The close association of these temperature proxies supports the assertion that snow accumulation occurs frequently through the year and that the isotope record initially contains temperature information from many times of the year. This is also independently confirmed by analysis of H2O2 data. The slope of the multi-year T vs δ correlation was evaluated along with the sub-annual variation in the amount, rate and timing of accumulation. These new results are consistent with those from the previous study and they also demonstrate that the snow in this area initially contains temperature and chemical records with sub-annual resolution. This encourages confident interpretation of the paleoclimatic signal variations in the GISP2 and GRIP deep cores.
Discrimination of glacier facies using multi-temporal SAR data
Authors: Partington K. C.
Published: September 2017

Glacier facies from the Greenland ice sheet and the Wrangell-St Elias Mountains, Alaska, are analyzed using multi-temporal synthetic aperture radar (SAR) data from the European Space Agency ERS-1 satellite. Distinct zones and facies are visible in multi-temporal SAR data, including the dry-snow facies, the combined percolation and wet-snow facies, the ice facies, transient melt areas and moraine. In Greenland and south-central Alaska, very similar multi-temporal signatures are evident for the same facies, although these facies are found at lower altitude in West Greenland where the equilibrium line appears to be found at sea level at 71°30?N during the year analyzed (1992-93), probably because of the cooling effect of the eruption of Mount Pinatubo. In Greenland, both the percolation and dry-snow facies are excellent distributed targets for sensor calibration, with backscatter coefficients stable to within 0.2 dB. However, the percolation facies near the top of Mount Wrangell are more complex and less easily delineated than in Greenland, and at high altitude the glacier facies have a multi-temporal signature which depends sensitively on slope orientation.
Improving digital elevation models over ice sheets using AVHRR-based photoclinometry
Authors: Scambos Ted A. , Fahnestock Mark A.
Published: September 2017

Advanced very high-resolution radiometer (AVHRR) images and a radar-altimetry-based digital elevation model (DEM) covering part of the northeast Greenland ice stream are combined to create an improved topographic map of the area using photoclinometry. In this application of photoclinometry, a DEM is used to establish the photometric relationship for two AVHRR images of a snow surface. Slopes from the DEM are compared with AVHRR data that are filtered (i.e. blurred) to the resolution of the DEM to give an empirical photometric determination. This is then used to convert unfiltered AVHRR data into quantitative slope measurements of the surface in the along-sun direction in each image, resolving features not present (or poorly represented) in the DEM. Co-registration of the images is based on the assumption that the two slope fields from the images describe one continuous smooth surface. The combined slopes are then converted to topography. In the test case, the technique adds topographic details with spatial scales of ~3 to ~20 km. A comparison of our results with airborne laser elevation profiles demonstrates that the new technique recovers most of the topography that is missed by the DEM. The improved topographic map reveals a ten-fold increase in local surface relief over the ice-stream feature, and shows the presence of shallow troughs over the shear margins of the feature.
Radar reflections reveal a wet bed beneath stagnant Ice Stream C and a frozen bed beneath ridge BC, West Antarctica
Authors: Bentley C. R. , Lord N. , Liu C.
Published: September 2017

Digital airborne radar data were collected during the 1987-88 Antarctic field season in nine gridded blocks covering the downstream portions of Ice Stream B (6km spacing) and Ice Stream C (11 km spacing), together with a portion of ridge BC between them. An automated processing procedure was used for picking onset times of the reflected radar pulses, converting travel times to distances, interpolating missing data, converting pressure transducer readings, correcting navigational drift, performing crossover analysis, and zeroing rémanent crossover errors. Interpolation between flight-lines was carried out using the minimum curvature method.

Maps of ice thickness (estimated accuracy 20 m) and basal-reflection strength (estimated accuracy 1 dB) were produced. The ice-thickness map confirms the characteristics of previous reconnaissance maps and reveals no new features. The reflection-strength map shows pronounced contrasts between the ice streams and ridge BC and between the two ice streams themselves. We interpret the reflection strengths to mean that the bed of Ice Stream C, as well as that of Ice Stream B, is unfrozen, that the bed of ridge BC is frozen and that the boundary between the frozen bed of ridge BC and the unfrozen bed of Ice Stream C lies precisely below the former shear margin of the ice stream.
Mapping subglacial surfaces of temperate valley glaciers by two-pass migration of a radio-echo sounding survey
Authors: Welch B.C. , Pfeffer W.T. , Harper J.T. , Humphrey N.F.
Published: September 2017

High-resolution maps of the glacier bed are developed through a pseudo-three-dimensional migration of a dense array of radio-echo sounding profiles. Resolution of three-dimensional maps of subglacial surfaces is determined by the radio-echo sounding wavelength, data sparing in the field, and migration. Based on synthetic radio-echo sounding profile experiments, the maximum resolution of the final map cannot exceed one half-wavelength. A methodology of field and processing techniques is outlined to develop a maximum-resolution map of the glacier bed. The field and processing techniques are used to develop a map of the glacier bed below part of Worthington Glacier, a temperate valley glacier in south-central Alaska. The field techniques and the processing steps used on the glacier result in a map of 20 m x 20 m resolution.
Precise dielectric profiling of ice cores: a new device with improved guarding and its theory
Authors: Wilhelms Frank , Kipfstuhl Josef , Miller Heinz , Heinloth Klaus , Firestone John
Published: September 2017

Dielectric profiling (DEP), a capacitive method for measuring an ice core’s electrical conductivity and permittivity, has been in use for several years. We have built an improved DEP instrument with a modified guarded-electrode geometry whose capacitance can be determined from potential theory. The new instrument can measure an ice core’s conductivity and permittivity to within a few per cent error, a high enough accuracy to infer its density using well-known models.
The Eclipse drill: A field-portable intermediate-depth ice-coring drill
Authors: Blake Erik W. , Wake Cameron P. , Gerasimoff Michael D.
Published: September 2017

A derivative of the Danish tipping-lower intermediate-depth ice-coring drill system has been developed for use in remote areas. The system as described is capable of drilling to depths of 250 m, although the drill has been proven to 350 m. The drill system is designed to be transported by hand and consumes 700 W maximum power from a 24 V Ac. battery bank charged by solar panels or a small generator. A field test in the St Elias Mountains, Yukon, produced good-quality core to 161.6 m depth; drilling at 6500 m a.s.l. on Far East Rongbuk Glacier, Mount Everest, produced good core to 42 m depth.
Using the temporal variability of satellite radar altimetric observations to map surface properties of the Antarctic ice sheet
Authors: Legrésy Benoît , Rémy Frédérique
Published: September 2017

The problem of measuring surface height and snowpack characteristics from satellite radar altimeter echoes is investigated. In this paper, we perform an analysis of the ERS1 altimeter dataset acquired during a 3 day repeat orbit. The analysis reveals that there are temporal variations in shapes of the radar altimeter echo and that these variations are linked to meteorological phenomena. The time- and space-scales over which these variations apply are a few to tens of days and a few hundred kilometres, respectively. This phenomenon, if not accounted for, can create error in the height measurement. A numerical echo model is used to recover snowpack characteristics by taking advantage of the temporal variations of the radar echoes. A map of penetration depth of the radar waves in the Ku band over the Antarctic continent is obtained and suggests that grain-size produces the dominant effect on radar extinction in the snowpack at this frequency. Finally, a procedure is proposed to correct the height measurement within the context of ice-sheet mass-balance survey.
Basal sliding of Ice Stream B, West Antarctica
Authors: Hermann Engelhardt , Barclay Kamb
Published: September 2017

A “tethered stake” apparatus is used to measure basal sliding in a borehole on Ice Stream B, West Antaretica, about 300 km upstream (east) from its grounding line near the head of the Ross Ice Shelf. A metal stake, emplaced at the top of a laver of unfrozen till underlying the ice, is connected by a tether line to a metering unit that measures the tether line as it is pulled out from the borehole by the stake as a result of basal sliding. The measured sliding motion includes any actual slip across the ice–till interface and may include in addition a possible contribution from shear deformation of till within about 3 cm of the interface. This 3 cm figure follows from a qualitative model of the movements of the stake in the course of the experiment, based on features of the record of apparent sliding. Alternative but less likely models would increase the figure from 3 cm to 10 cm or 25 cm. In any case it is small compared to the seismically inferred till thickness of 9 m. Measured apparent sliding averages 69% of the total motion of 1.2 m d−1 over 26 days of observation if a 3.5 day period of slow apparent sliding (8% of the total motion) is included in the average. The occurrence of the slow period raises the possibility that the sliding motion switches back and forth between c.80% and c. 8% of the total motion, on a time-scale of a few days. However, it is likely that the period of slow apparent sliding represents instead a period when the stake got caught on the ice sole. If the slow period is therefore omitted, the indicated average basal sliding rate is 83% of the total motion. In either case, basal sliding predominates as the cause of the rapid ice-stream motion. In the last 2 days of observation the average apparent sliding rate reached 1.17 m d−1, essentially 100% of the motion of the ice stream. If till deformation contributes significantly to the ice-stream motion, the contribution is concentrated in a shear zone 3 cm to possibly 25 cm thick at the top of the 9 m thick till layer. These observations, if applicable to the West Antaretic ice sheet in general, pose complications in modeling the rapid ice-streaming motion.
The mass balance of McCall Glacier, Brooks Range, Alaska, U.S.A.; its regional relevance and implications for climate change in the Arctic
Authors: Rabus B.T. , Echelmeyer K. A.
Published: September 2017

McCall Glacier has the only long-term mass-balance record in Arctic-Alaska. Average annual balances over the periods 1958–72 and 1972–93 were –15 and –33cm, respectively; recent annual balances (1993–96) are about –60 cm, and the mass-balance gradient has increased. For an Arctic glacier, with its low mass-exchange rate, this marks a significant negative trend.

Recently acquired elevation profiles of McCall Glacier and ten other glaciers within a 30 km radius were compared with topographic maps made in 1956 or 1973. Most of these glaciers had average annual mass balances between –25 and –33 cm, while McCall Glacier averaged –28 cm for 1956–93, indicating that it is representative of the region. In contrast, changes in terminus position for the different glaciers vary markedly. Thus, mass-balance trends in this region cannot be estimated from fractional length changes at time-scales of a few decades.

We developed a simple degree-day/accumulation mass-balance model for McCall Glacier. The model was tested using precipitation and radiosonde temperatures from weather stations at Inuvik, Canada, and Barrow, Kaktovik and Fairbanks, Alaska, and was calibrated with the measured balances. The Inuvik data reproduce all measured mass balances of McCall Glacier well and also reproduce the long-term trend towards more negative balances. Data from the other stations do not produce satisfactory model results. We speculate that the Arctic Front, oriented east–west in this region, causes the differences in model results.
The sliding velocity over a sinusoidal bed at high water pressure
Authors: Truffer Martin , Iken Almut
Published: September 2017

Under idealized conditions, when pressurized water has access to all low-pressure areas at the glacier bed, a sliding instability exists at a critical pressure, pc, well below the overburden pressure, p0. The critical pressure is given by , where l is the wave length and a is the amplitude of a sinusoidal bedrock, and T is the basal shear stress. When the subglacial water pressure, pw, approaches this critical value, the area of ice-bed contact, △l, becomes very small and the pressure on the contact area becomes very large. This pressure is calculated from a force balance and the corresponding rate of compression is obtained using Glen’s flow law for ice. On the assumption that compression in the vicinity of the contact area occurs over a distance of the order of the size of this area, Δl, a deformational velocity is estimated. The resultant sliding velocity shows the expected instability at the critical water pressure. The dependency on other parameters, such as wavelength l and roughness a/l, was found to be the same as for sliding without bed separation.
Sensitivity of Rhonegletscher, Switzerland, to climate change: experiments with a one-dimensional flowline model
Authors: Wallinga Jakob , Van De Wal Roderik S.W.
Published: September 2017

A one-dimensional time-dependent flowline model of Rhonegletscher, Switzerland, has been used to test the glacier’s response to climatic warming. Mass-balance variations over the last 100 years are obtained from observations of the equilibrium-line altitude (ELA) and a reconstruction of the ELA based on a statistical correlation between temperature and ELA. For the period prior to AD 1882, for which no reliable climate data exist, we chose equilibrium-line altitudes that enabled us to simulate accurately the glacier length from AD 1602.

The model simulates the historical glacier length almost perfectly and glacier geometry very well. It underestimates glacier-surface velocities by 1-18%. Following these reference experiments, we investigated the response of Rhonegletscher to a number of climate-change scenarios for the period AD 1990-2100. For a constant climate equal to the 1961-90 mean, the model predicts a 6% decrease in glacier volume by AD 2100. Rhonegletscher will retreat by almost 1 km over the next 100 years at this scenario. At a warming rate of 0.04 K a-1, only 4% of the glacier volume will be left by AD 2100.
Evolution of a Surge-Type Glacier in its Quiescent Phase: Kongsvegen, Spitsbergen, 1964–95
Authors: Melvold Kjetil , Ove Hagen Jon
Published: September 2017

Kongsvegen is a 102 km2 sub-polar (polythermal) surge-type glacier in northwest Spitsbergen, Svalbard. It surged just before 1948 and is currently in its quiescent phase. Measurements of surface geometry since 1966 show a retreat of the front and strong thinning of up to 75 m in the ablation area, and a build-up of up to 32 m in the accumulation area. Present-day annual velocities along the glacier are low, from 1.4 up to 3.6 m a-1. The measured mean net balance for the period 1987-94 and the balance reconstructed back to 1967 show a weak positive balance of about 0.1 m w.e. The measured actual ice flux is low and the mass transfer down-glacier at the ELA is only about 3-20% of that required for steady state. Thus, the glacier is building up towards a new surge. The total thickening rate on Kongsvegen is somewhat higher than in other cases from Svalbard, but it is small compared with other well-studied surge-type glaciers in Alaska and the Pamirs. This relatively low rate of change is a function of the low accumulation rate and the relatively cold climate compared to other areas and is common for surge-type glaciers in Svalbard.
Ice-shelf dynamics near the front of the Filchner-Ronne Ice Shelf, Antaretica, revealed by SAR interferometry: model/interferogram comparison
Authors: MacAyeal Douglas R , Rignot Eric , Hulbe Christina L
Published: September 2017

We compare European remote-sensing satellite (ERS) synthetic aperture radar interferograms with artificial interferograms constructed using output of a finite-element ice-shelf flow model to study the dynamics of Filchner-Ronne Ice Shelf (FRIS), Antaretica, near Hemmen Ice Rise (HIR) where the iceberg-calving front intersects Berkner Island. We find that the model must account for rifts, mechanically competent sea ice which fills rifts, and ice softening in coastal boundary layers in order to agree with the ice-deformation pattern implied by observed interferograms. Analysis of the stress field in the model experiment that best matches the observed interferograms suggests that: (1) HIR introduces weakness into the ice shelf through the generation of large-scale rifts, and (2) the melange of sea ice and ice-shelf fragments that fills the rifts stabilizes the shelf front by providing mechanical coupling between the fractured shelf front and the adjacent coast. The rift-filling melange could melt more easily than the surrounding ice shelf and thus could represent a vulnerability of the FRIS to climate warming.
The thermal conductivity of seasonal snow
Authors: Sturm Matthew , Holmgren Jon , König Max , Morris Kim
Published: September 2017

Twenty-seven studies on the thermal conductivity of snow (Keff) have been published since 1886. Combined, they comprise 354 values ofKeff, and have been used to derive over 13 regression equation and predictingKeffvs density. Due to large (and largely undocumented) differences in measurement methods and accuracy, sample temperature and snow type, it is not possible to know what part of the variability in this data set is the result of snow microstructure. We present a new data set containing 488 measurements for which the temperature, type and measurement accuracy are known. A quadratic equation,

whereρis in g cm−3, andKeffis in W m−1K−1, can be fit to the new data (R2= 0.79). A logarithmic expression,

can also be used. The first regression is better when estimating values beyond the limits of the data; the second when estimating values for low-density snow. Within the data set, snow types resulting from kinetic growth show density-independent behavior. Rounded-grain and wind-blown snow show strong density dependence. The new data set has a higher mean value of density but a lower mean value of thermal conductivity than the old set. This shift is attributed to differences in snow types and sample temperatures in the sets. Using both data sets, we show that there are well-defined limits to the geometric configurations that natural seasonal snow can take.