ScholarWorks@UA: Recent submissions
Now showing items 1-20 of 12571
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Electrical conductivity, freezing temperature, and salinity relationships for seawater and sodium chloride solutions for the salinity range from 0 to over 200 PPTAlgorithms for the conversion of electrical conductivity to salinity (and vice-versa) for seawater and sodium chloride solutions were developed. Algorithms developed for seawater were based on laboratory measurements of synthetic seawater were based on laboratory measurements of synthetic seawater solutions and are valid for the salinity range from 0 to about 212 ppt at temperatures of 15, 20 and 25°C. Algorithms developed for NaCl solutions were based on literature data and are valid for the salinity range from 0 to about 250 ppt at temperatures of 20 and 25°C. Previous work by others for the conversion of salinity to the freezing temperature for seawater solutions is discussed. From this work, expressions for the conversion of the freezing temperature to salinity were derived and are given for the salinity range from 0 to about 230 ppt. Algorithms for the conversion of salinity to the freezing temperature (and vice-versa) for sodium chloride solutions were developed, based on literature data, for the salinity range from 0 to about 230 ppt.
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Promoting Positive Traffic Safety Culture in RITI Communities through Active Engagement: Implementation Guide and Outreach ActivitiesRural, Indigenous, Tribal, and Isolated (RITI) communities’ crash data analysis clearly highlights three major areas of concern: prevalence of excessive speed, impaired and distracted driving, and underage driving. Safety-focused educational programs and awareness campaigns have all contributed to a reduction in crashes in urban areas. However, in RITI communities, much more work is still needed. It is important that communities are provided with the proper resources and methods to deliver the appropriate training and educational tools that promote and cause a significant positive change in the traffic safety culture. Through reviewed literature and interviews with tribal community stakeholders, this research team came to understand that tribal youth are most impacted and engaged when educational material is made culturally relevant. We then developed an implementation guide to be used by tribes to create, develop, and enact a sustained educational program with the mission to positively impact traffic safety culture among youth in tribal and rural communities.
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Experiment LuxembourgThe radio-wave interaction technique has been applied to the study of the lower ionosphere at College, Alaska. The system employs a pulsed wanted transmitter operating at a frequency of 4.86 Mc/s and a pulsed disturbing transmitter operating at 17.5 Mc/s with an output power of 100 kw. Radio-wave interaction has been recorded over the elevation range from 30 to 70 km. The system is best adapted to observations under somewhat disturbed ionospheric conditions. The observed interaction normally shows significant variation within time intervals of the order of minutes. Some collision frequency and electron density values have been derived. The disturbing transmitter, the 4x4 array of 3-element Yagi antennas, and the receiving circuitry have been adapted to allow the reception of backscatter signals at the disturbing frequency or cosmic noise on an adjacent frequency. Analysis of system performance in the various modes of operation is continuing.
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On the strong influence of the F1 layer on medium to high latitude HF propagationDuring the recent sunspot minimum of the F1 layer critical frequency was close to that of the F2 in the medium to high latitudes. This considerably modified HF propagation conditions over long distance paths. At times the F1 layer appeared to block off the propagation of signals in the very oblique F2 modes. High order F2 mode signals were frequently strong and were reflected from large virtual heights. This retardation was produced by the dense, thick F1 layer which existed in the medium to high latitudes during the summer of 1964. The maximum radio frequency for the path was frequently determined by the F1 layer; although this effect has been noted by various workers, it has not been taken into account for communications predictions. One particularly strong and highly delayed type of signal is not readily explainable as a higher order F2 mode because it occurred singly. If it were an ordinary F2 mode trace, its occurrence would lead to the conclusion that the only F2 layer signal propagating was a third or fourth order mode signal on paths of 3500 to 5000 km, and such a conclusion is hard to justify. As an alternative, an F1-F2 ducted mode hypothesis is presented.
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Interpretation of geophysical well logs in permafrostThis report is a collection of information on the interpretation of well logs and borehole geophysical surveys in permafrost. The body of the report is preceded by an executive summary that gives the highlights of the report in condensed form. The introductory chapter contains background information that is fundamental to the understanding of well log applications in permafrost, including definitions and descriptions of well logs, permafrost, and related terms, and illustrations showing the extent of permafrost in Alaska. Chapter 2 presents information on physical properties of permafrost that relate to well log interpretation, including porosity and pore-filling media (water, ice and air), and their effects on thermal properties, electrical properties and acoustic properties. Chapters 3-8 describe the following types of well logs in detail, including measurement principles and methods, procedures for calibration and interpretation, and identification of special problems related to permafrost: thermal logs, electric logs, sonic logs, nuclear logs, magnetic logs, and miscellaneous (caliper and drilling) logs. Chapter 9 gives information on three types of borehole geophysical surveys, electrical resistivity, seismic velocity, and borehole gravity, with emphasis on the increased depth of investigation afforded by these surveys as compared with well logs. Chapter 10 described a number of specific applications, including the identification of lithology in permafrost, characterization of the thermal regime and the thermal properties of permafrost, petroleum exploration and production, mining applications, and geotechnical applications. A concluding chapter summarizes the information contained in the body of the report and includes a table that gives an overview of the relative value of various borehole geophysical measurements that can be used for delineating and characterizing permafrost. Conclusions of the report are that a number of standard borehole measurement techniques have been tried and proven in permafrost and can be used effectively to delineate and characterize earth material penetrated by the borehole. However, there are several well logging techniques that have special potential for detecting permafrost that have not been tested: dielectric constant, sonic waveform, televiewer, and nuclear magnetic resonance. Borehole electrical and seismic surveys have potential for detecting permafrost at large distances from the borehole, and these techniques need further development and refinement to take full advantage of their capability.
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Tracking the aurora by a multifrequency HF backscatter sounderA comparison of simultaneous optical and radio auroral data obtained during 12 days in December, 1964, shows conclusively that the radio wave scattering belt includes the visual auroral belt. The optical data were obtained with the Alaskan network of all-sky-cameras located between 65 and 80° north geomagnetic latitude. With the exception of vertical incidence, meteor, groundscatter, and slant F (polar spur) traces, all of the recorded backscatter traces from the north were scaled indiscriminately for slant range. The excellent agreement that resulted leads us to conclude that the majority of the HF and low VHF backscatter echoes observed at high latitudes are auroral echoes in the strict sense of the term. In the records shown the auroral belt was tracked from 65 to above 80°N geomagnetic latitude. It is concluded that the multifrequency HF backscatter sounder makes year-round observations of the auroral belt possible.
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Effective recombination coefficient in D-regionThe effect of the meteoric dust particles on the steady state distribution of electrons and ions in the lower ionosphere (50-90 km) has been investigated. It is shown that the effective recombination coefficient obtained is higher than that obtained by ignoring the presence of dust. (Abstract excerpt.)
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Ice cover development on interior Alaska streamsA number of photographs are presented which illustrate selected aspects of frazil ice formation in turbulent Interior Alaska streams. These include the various forms of frazil ice found in turbulent streams and the processes involved in the development of an ice cover on the streams. All of the photographs depict frazil ice under field conditions. They include photographs of cooling conditions, frazil discs (both in situ and removed from the stream), anchor ice, edge ice, frazil flocs, frazil pans, snow slush, and frazil floes. Photographs of hydrological conditions that lead to the production of large frazil ice floes and of different types of frazil ice jams are also included. These photographs provide visual documentation of the key role that frazil ice plays in ice cover development on turbulent streams in Interior Alaska.
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Asymmetry of Dst variations of geomagnetic storms with respect to the geomagnetic equatorThe seasonal variations in the Dst part of magnetic storms are determined for three pairs of stations, each pair consisting of two stations at nearly equal geomagnetic latitudes in the northern and southern hemispheres. The results show that in solstitial seasons the Dst field is not symmetrical with respect to the geomagnetic equator. The asymmetry is small in low latitudes and increases toward the auroral zones. Dm has a similar asymmetry with respect to the equator. These characteristics of Dst and Dm are interpreted as due to the asymmetry of auroral electrojets with respect to the geomagnetic equator in solstitial seasons.
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Differential use of willow species by moose in AlaskaPatterns of differential winter utilization of willow by moose in Interior Alaska and the Kenai Peninsula were studied during 1977 and 1978. Knowledge of such patterns is important to the wildlife manager who must evaluate the relative importance of different habitat types for moose. The study areas were composed of sites dominated by mature and seral habitat types.
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Alaska Earthquake Center Quarterly Technical Report April-June 2024This series of technical quarterly reports from the Alaska Earthquake Center (AEC) includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, fieldwork, our online presence, and lists publications and presentations by AEC staff. Multiple AEC staff members contribute to this report. It is issued within 1-2 months after the completion of each quarter Q1: January-March, Q2: April-June, Q3: July-September, and Q4: October-December. The first report was published for January-March, 2021.
