• Taking a stand on not taking a stand: media bias in the online reporting of COVID-19

      Johnson, Kyle; Hum, Richard; Taylor, Karen; Timm, Kristin (2021-05)
      This thesis was written to examine the digital communication strategies of three major news organizations when reporting on COVID-19 in the U.S. for bias. The research looked at social media posts, online article counts and themes, main websites of each organization and audio/visual broadcast segments from all three organizations posted online. This research used an advocacy approach, examining the tension between entertainment and journalism ethics by holding news organizations to journalism standards to see how they compare. Results showed that NPR and Fox News produced more online articles than MSNBC and linked to their own articles on twitter more. The audiovisual content from MSNBC and Fox News did not follow the code of ethics created by the Society of Professional Journalists. All three organizations used biased methods for providing information to the public, during a time period where public knowledge is key to managing a pandemic.
    • Technical and economic evaluation of the first ever polymer flood field pilot to enhance the recovery of heavy oils on Alaska's North Slope via machine assisted reservoir simulation

      Keith, Cody D.; Zhang, Yin; Ahmadi, Mohabbat; Dandekar, Abhijit (2022-05)
      Polymer flooding has become globally established as a potential enhanced oil recovery method for heavy oils. To determine whether this technology may be useful in developing the substantial heavy oil resources on the Alaska North Slope, a polymer flood field pilot commenced at the Milne Point Unit in August 2018. This study seeks to evaluate the results of the field pilot on a technical and economic basis. A reservoir simulation model is constructed and calibrated to predict the oil recovery performance of the pilot through machine-assisted reservoir simulation techniques. To replicate the early water breakthrough observed during waterflooding, transmissibility contrasts are introduced into the simulation model, forcing viscous fingering effects. In the ensuing polymer flood, these transmissibility contrasts are reduced to replicate the restoration of injection conformance during polymer flooding. Transmissibility contrasts are later reinstated to replicate fracture overextension interpreted in one of the producing wells. The calibrated simulation models produced at each stage of the history matching process are used to forecast oil recovery. These forecasts are used as input for economic analysis, incremental to waterflooding expectations. The simulation forecasts indicate that polymer flooding significantly increases the heavy oil production for this field pilot compared to waterflooding alone, yielding attractive project economics. However, meaningful variations between simulation scenarios demonstrate that a simulation model is only valid for prediction if flow behavior in the reservoir remains consistent with that observed during the history matched period. Critically, this means that a simulation model calibrated for waterflooding may not fully capture the technical and economic benefits of an enhanced oil recovery process such as polymer flooding. Subsequently, the simulation model and economic model are used in conjunction to conduct a sensitivity analysis for polymer flood design parameters, from which recommendations are provided for both the continued operation of the current field pilot and future polymer flood designs. The results demonstrate that a higher polymer concentration can be injected due to the development of fractures in the reservoir. The throughput rate should remain high without exceeding operating constraints. A calculated point-forward polymer utilization parameter demonstrates the decreasing efficiency of the polymer flood at later times in the pattern life. Future projects will benefit from starting polymer injection earlier in the pattern life. A pattern with tighter horizontal well spacing will observe a greater incremental benefit from polymer flooding.
    • Temporal and size-based patterns in juvenile sablefish energy allocation and diet

      Callahan, Matthew W.; Beaudreau, Anne H.; Mueter, Franz J.; Heintz, Ronald A. (2020-08)
      A recent marine heatwave in the Gulf of Alaska caused depressed growth, poor body condition, and low survival in many fish species, but juvenile sablefish (Anoplopoma fimbria) thrived. These fast-growing piscivores are the target of a valuable commercial fishery in Alaska as adults and have historically shown high variability in recruitment. The first winter is a period of nutritional stress and high mortality for many fish species and first winter survival may dictate year class strength, but the importance of the first winter for juvenile sablefish is understudied. We examined juvenile sablefish energy storage, growth, and diet during their first two years of life, specifically as newly settled juveniles in their first autumn, in late winter, and during their second summer and autumn. Sablefish grew rapidly in autumn and growth slowed but continued through winter. Mean energy density (kJ g⁻¹) declined over the winter but total energy (kJ individual⁻¹) increased significantly between October and March. Slopes of energy density and total energy versus length regressions were atypical for high latitude marine fish in that they were steepest in March. This indicates that large fish grew during winter with minimal energy depletion while small fish grew but depleted their energy stores. Stable isotope results revealed that larger fish were enriched in [delta]¹³C and [delta]⁻¹⁵N in March relative to smaller fish, suggesting diet differences may contribute to size-specific energy storage patterns during winter. Pacific herring (Clupea pallasii) dominated diets but consumption of herring and other prey varied seasonally and annually. Relative stomach content weights were highest in autumn 2018, which was a period of rapid growth. Results of this study show advantages for sablefish achieving large size prior to winter and broadly support the hypothesis that first winter is a life history bottleneck for juvenile sablefish. The generalist feeding strategy of sablefish and rapid growth early in life may provide the ability to adapt to a wide range of environmental conditions.
    • Theory, design, and development of an open-source 3D printed peristaltic pump for microfluidics applications

      MacEachern, Joshua M.; Chen, Cheng-fu; Peterson, Rorik; Huang, Daisy; Laughlin, Bernard (2022-05)
      Microfluidics research is a constantly evolving and developing field of research in the biological, chemical, and medical sciences. To perform microfluidic analyses, various types of pump designs have been developed or optimized. These pumps are generally capable of pumping flow in the range of 0.1-100s of microliters (µL) per minute, with the goal of pumping fluid with an extremely consistent flow rate. These pumps include, but are not limited to, peristaltic, syringe, membrane, and lobe pumps. Both commercial and open-source designs have been developed to meet the needs of continued research. Commercial designs are very expensive, but offer limited flexibility to tailor the usage for custom assays. Open-source designs that have been presented may lack support, or may be designed to use fabrication technologies that are less commonly available than conventional desktop 3D printing. Due to this, many laboratories may be limited in their microfluidic research work due to either availability of commercial pumps, or usability of open-source pump designs. This work presents two iterations of a novel design for a 3D-printable microfluidic peristaltic pump. The pumps developed herein have been tested to demonstrate consistent performance operating over long-term periods of up to ten days continuously. These pumps have been tested to demonstrate capability of delivering aqueous flow as slow as flow ranges of 10s of µL/min. These pumps are capable of maintaining an outlet pressure of up to 220 kilopascals (kPa). In a tube of 1 mm inner diameter, this pressure would drive a flow rate of 10 µL/min through tubing up to 6.6 meters long. Finally, this design has been optimized to improve the user experience and make these peristaltic pumps both easy to maintain and easy to operate by a non-technical user.
    • Timescales of magmatic processes from diffusional profiles recorded in minerals of the 2016-2017 eruption of Bogoslof Volcano, Alaska

      Moshrefzadeh, Jamshid Akhbar; Izbekov, Pavel; Loewen, Matthew; Larsen, Jessica; Regan, Sean (2020-08)
      Every volcanic eruption is unique, and creates opportunities for scientists to gain insights on magma processes. Studying active volcanoes not only adds to our understanding of fundamental processes that shape our planet, but it is also importantly aids the scientic community to assess and mitigate the many hazards that volcanoes pose. The products of the 2016-2017 eruption of Bogoslof Volcano provide a unique opportunity for the application of diusion chronometry, due to the abundance of distinct, stepwise boundaries within three mineral phases: clinopyroxene, plagioclase, and amphibole. Given that diusion is driven by the presence of a chemical gradient, the compositionally stepwise boundaries between distinct zones can be used to investigate the diusion of elements within the crystals in order to constrain timing of the magmatic processes that created them, as well as crystal residence times. Here we present our analyses of these stepwise boundaries, and discuss the potential correlation of acquired diusional timescales from clinopyroxene with the other two mineral phases, in order to determine what magma processes lead to the formation of these boundaries, and when these processes occurred. Our results suggest that the stepwise boundaries in crystalline phases of the magmas erupted by Bogoslof in August 2017 formed due to mac recharge that resumed in March 2017 and occurred repeatedly until the cessation of the eruption in August 2017. Activity at Bogoslof during March 2017 is additionally characterized by increased seismicity and SO₂ rates, suggesting that our petrologic results are consistent with multiple interdisciplinary observations.
    • Tracing carbon sources of southern Beaufort Sea and Chukchi Sea polar bears using stable isotope analyses

      Smith, Malia E.K.; Horstmann, Lara; Wooller, Matthew; Rode, Karyn (2020-12)
      The Southern Beaufort Sea (SBS) polar bear (Ursus maritimus) subpopulation has declined in response to sea ice loss, while the Chukchi Sea (CS) subpopulation appears stable. The substantial population decline in the SBS subpopulation in recent years is concurrent with increases in the proportion of polar bears coming on shore, and the duration they spend there. Both of these changes have been associated with the loss of access to their primary sea ice habitat, which is mainly used as a platform to hunt seals. The first objective of this study was to determine if the SBS and CS polar bear subpopulations could be distinguished based on stable isotope signatures (delta¹³C and delta¹⁵N values) of bone collagen. The second objective was to examine patterns in SBS polar bear trophic level and terrestrial carbon sources over a 65-year time period, as polar bears have increasingly used coastal environments. We analyzed 112 SBS and CS polar bear bones (predominantly mandibles) from 1954-2019 that had been archived at the University of Alaska Museum of the North, as well as bones from subsistence-harvested polar bears. In addition to delta¹³C and delta¹⁵N, samples from the SBS bears were analyzed for compound-specific stable carbon isotopes of amino acids (delta¹³CAA values). Another 50 bone collagen samples from terrestrial mammals and pinnipeds from northern Alaska were analyzed for delta¹³CAA values to provide a regional comparative dataset. Our study showed a significant difference in bulk delta¹³C (p<0.001) values, but not delta¹⁵N (p=0.654) values between the CS (-13.0‰±0.3‰ and 22.0‰±0.9‰, respectively) and the SBS bears (-14.7‰±1.3‰ and 22.2‰±1.0‰, respectively). We performed a logistic regression analysis (LR) using bulk delta¹³C and delta¹⁵N values of the polar bears to predict their placement into these two subpopulations. Using Icy Cape, AK as the geographical boundary, LR correctly placed polar bears in their respective subpopulations 82% of the time. Overall accuracy of placement changed to 84% when using the current geographical boundary at Utqiaġvik, AK. Bone collagen has a slow turnover rate, providing long-term, potentially life-long stable isotope signatures. Our findings could be used to determine the association of harvested polar bears to Alaska subpopulations, thus aiding in harvest quota management. The LR predicted samples collected from the Wainwright, AK region to be 58% CS and 42% SBS polar bears. This indicates that the area between Wainwright and Icy Cape is a polar bear mixing zone that includes bears from both subpopulations. Over the 65-year study period, two distinct groups of SBS polar bears were identified based on their delta¹³C values of the amino acid proline: a high delta¹³CPro group (1.8‰±2.3‰, n=45) and a low delta¹³CPro group (-15.7‰±1.9‰, n=26). The high proline polar bear group had delta¹³CPro values similar to those of Arctic brown bears (Ursus arctos; 0.4‰±1.6‰), while the low group had delta¹³CPro values similar to ice seals (-15.3‰±1.2‰). Among the available samples, there were more high proline/pelagic bears (n=17) after the 2007 sea ice minimum than high proline/coastal bears (n=12), which is opposite of what we expected. This study provides evidence that two distinct ecotypes in Southern Beaufort Sea polar bears, pelagic and coastal, have existed since at least the 1950's. Overall, our results represent a detailed isotopic view of the Alaskan polar bear subpopulations, demonstrating the possibility of distinguishing and categorizing individuals as either SBS or CS, while also highlighting the existence of two ecotypes in the SBS subpopulation.
    • Training the next generation of climate science integrators: lessons from the Landscape Conservation Cooperatives

      Rowles, Fiona; Trainor, Sarah; Valentine, David; Fix, Peter (2021-12)
      Science that can be readily applied to policy or decision-making is a critical component of adapting to the climate emergency. Boundary spanning facilitates the creation of credible, relevant, and legitimate science for use in policy and decision making. Individuals who are adept at navigating the interface between science and decision making (referred to as "boundary spanners") are crucial in developing science that fits the needs of managers. Though the attributes and skills needed to be an effective boundary spanner are well-defined, individuals are not often trained for these roles. This study incorporates two sets of interviews conducted with employees and affiliates of the Landscape Conservation Cooperatives (LCCs), a boundary spanning organization that was administered by the U.S. Fish and Wildlife Service between 2010 and 2017. Participants across the LCC Network were asked which training they considered to be most effective in their role as a boundary spanner, what changes resulted from that training, and if they had been trained in co-production of knowledge or boundary spanning. Participants from the five Alaskan LCCs who attended a science communication workshop in 2015 were asked about their job tasks, science communication barriers, and goals within their LCC. Participants cited a number of different trainings that they considered to be effective. Trainings involving decision theory and peer-to-peer learning opportunities were referenced slightly more frequently than other trainings. Changes to the strategic plan and overall direction of the organization was the most often cited training outcome. Capacity (funding, time, or skills) was the most frequently cited barrier to science communication among the Alaskan LCCs. Small boundary-spanning organizations may benefit from increasing capacity by hiring individuals who already possess necessary skills, or by focusing on science translation rather than generating new science. Boundary spanners should be encouraged to access peer-to-peer learning environments and training in decision making.
    • Transport of CH₄ through open-talik lakes in discontinuous permafrost aquifers

      Eckhardt, Bridget A.; Barnes, David L.; Daanen, Ronald P.; Liljedahl, Anna K.; Romanovsky, Vladimir E.; Anthony, Katey Walter (2020-08)
      As northern regions of the world experience warming climate, scientists look to permafrost, a crucial component of Arctic and subarctic ecosystems, as a source and sink of atmospheric carbon. It is well-known that the thawing of permafrost from above as a result of warming climate is a considerable source of greenhouse gases. However, few studies have considered the production of methane, a potent greenhouse gas, beneath the permafrost. A rugged permafrost bottom is proposed to favor the storage of gas in "pockets" that have been formed through permafrost thaw and degradation from below. Sub (below)-permafrost methane can migrate to reach the atmosphere when connections between the sub-permafrost and supra- permafrost open pathways from the pocket to the bottom of an open talik lake. We hypothesized that the migration of methane occurs through advection and diffusion as a dissolved gas and by movement as an immiscible fluid. Through measurement of environmental tracers in two thermokarst lakes in Goldstream Creek Basin, Fairbanks, Alaska, we found that advection was variable and was seasonally and climatically dependent demonstrating both upward and downward groundwater flow within our study lakes. Measurements of dissolved methane concentrations in the lakes demonstrated that diffusion of methane was not a significant transport mechanism in the groundwater-to-lake pathway due to the extreme temporal and spatial variability of methane concentrations. Immiscible flow of free-phase methane is likely the dominant transport mechanism but is dependent on the lake sediment composition and the formation of secondary pathways within the talik. Data obtained from this study allowed for a better understanding of methane transport and thermokarst lake dynamics.
    • Trend analysis of temperature, precipitation, and stream flow in the National Petroleum Reserve Alaska

      Marshall, Sara; Toniolo, Horacio; Rasley, Brian; Schnabel, William (2021-05)
      Seven hydro-meteorological stations in the National Petroleum Reserve Alaska were analyzed to look at precipitation, discharge, and temperature trends. These hydro-meteorological stations included: Fish Creek, Judy Creek, Ikpikpuk, Ublutuoch, Seabee, Prince, and Otuk. A linear regression was performed on a year-by-year basis to fill in data gaps in the temperature time series, for all six stations with temperature data. The Seasonal Mann-Kendall test and a Modified Seasonal Mann-Kendall test were performed to determine if a trend appeared present in the time series and, if so, how significant the trend was. The Sen's slope analysis was then utilized to determine the magnitude of the trend, if a trend was observed in both analyses. The temperature trends showed an increasing trend in the temperature data for four stations: Judy Creek, Ublutuoch, Fish Creek, and Ikpikpuk. No trend was shown in the remaining station, Otuk station. One station, Prince, was removed from analysis due to a high percentage of missing data. The Modified Seasonal Mann-Kendall tests showed a trend in four of the five stations, and a slight positive trend in one of the five stations. The precipitation data showed 'no trend' in the Seasonal Mann-Kendall analysis. The Modified Seasonal Mann-Kendall test showed a slight trend (Fish Creek), a moderate trend (Otuk), and no trend (Ikpikpuk) for the precipitation data. Using the seasonal Mann-Kendall analysis the discharge data showed no trend in five out of seven stations and two trends (Fish Creek and Seabee). The Modified Seasonal-Mann-Kendall analysis showed and a significant trend twice (Fish Creek and Seabee), a moderate trend three times (Ikpikpuk, Prince, Otuk), a slight trend once (Ublutuoch), and no trend one time (Judy Creek) in the discharge data.
    • Trophic structure of rocky intertidal communities in contrasting high-latitude environments

      Siegert, Danielle; Iken, Katrin; Konar, Brenda; Lindeberg, Mandy (2020-08)
      Coastal ecosystems in high latitudes are increasingly impacted by glacial melt and river discharge due to climate change. One way to understand ecosystem responses to these stressors is assessing trophic relationships. The goal of this study was to better understand how hydrographic conditions influence trophic structure in high-latitude rocky intertidal systems. I compared the trophic structure of rocky intertidal assemblages in two regions in the northern Gulf of Alaska that comprise the same regional species pool but are hydrographically distinct, one glacially influenced and one primarily marine influenced. Common macroalgal and invertebrate taxa, as well as particulate organic matter (POM) were sampled at three rocky intertidal communities in each region in 2017 and 2018. Food web structure was compared using trophic metrics based on the distribution of shared taxa in isotopically-derived (delta¹³C and delta¹⁵N) trophic niche space. I found that trophic niche space in the glacially-influenced rocky intertidal system was larger, driven by larger ranges in both carbon and nitrogen stable isotope values. In particular, the lower delta¹³C values in Kamishak Bay suggest that an additional food source, most likely terrestrial organic material from glacial discharge, was incorporated into the food web. This supported the hypothesis that patterns in food web structure differed based on hydrographic influences to maintain overall stability. Isotopic evenness, i.e., the distribution of the shared taxa within trophic space, did not differ between the two regions. Macroalgae were overall a more important food source than POM in both regions, and even more so in the glacially-influenced region, where macroalgae may be an energetically beneficial food source compared to silt-laden glacial inputs. This study showed that common intertidal taxa have high tropic flexibility enabling them to respond to variable food sources under a variety of environmental conditions. As hypothesized, taxa in food webs occupying a larger trophic niche space engaged in more heterogeneous trophic pathways and used diverse resources depending on local environmental conditions, making these systems more stable to perturbations affecting a single resource. The common taxa of high-latitude rocky intertidal systems studied here are responding to current levels of glacial input with more diverse resource use, but it remains to be seen how well those systems are suited to maintain trophic stability with an expected increase in glacial stress from climate warming.
    • Tropospheric reactive bromine and meteorology over the Arctic Ocean

      Swanson, William; Simpson, William; Guerard, Jennifer; Trainor, Thomas; Mao, Jingqiu (2021-08)
      During late winter and spring in the Arctic, unique chemistry produces high levels of reactive bromine radicals (e.g., bromine atomic radicals and bromine monoxide, BrO) in the lower troposphere. These high levels of bromine radicals react with and reduce ambient ozone and oxidize gaseous elemental mercury. These reactive bromine species are chemically released from frozen saline surfaces and are affected by meteorological processes such as transport and mixing. Prior work has proposed that heterogenous reactions on snowpack surfaces as well as on atmospheric particle surfaces contribute to the reactive bromine production. We investigate these hypotheses using an extensive dataset of lower-tropospheric BrO observations from the Arctic Ocean and Utqiaġvik (formerly Barrow). First, we combine BrO observations with meteorological data and use principal component analysis to determine what environmental processes are correlated with BrO. We find that increased levels of reactive bromine under two sets of meteorological conditions: 1) stable, poorly vertically mixed conditions with temperature inversions, and 2) low-atmospheric-pressure conditions with increased vertical mixing. A principal component regression model based on these correlations predicted both the vertical column density of BrO in the lowest 2 km of the troposphere (R = 0.45) and the vertical column density of BrO in the lowest 200 m (R = 0.54). Next, we compare BrO observations to a global chemicaltransport model, GEOS-Chem, which was recently modified to add a blowing snow sea salt aerosol particle source. The GEOS-Chem model including the blowing snow process predicts monthly averaged BrO within experimental error for 9 of 13 total months of observations in Spring 2015 but cannot replicate hourly peaks in observed BrO. The model also predicts BrO during the Fall, which is not supported by the observations, potentially indicating a problem with the blowing snow model. We improve GEOS-Chem by adding a snowpack source of molecular bromine arising from deposition of precursor species such as ozone. Adding this snowpack molecular bromine source improves the agreement between the model and the observed monthly BrO at Utqiaġvik. However, a prior literature form of this model that had assumed an increased daytime yield of molecular bromine due to photochemistry leads to overprediction of radical bromine and is not supported. We find that using both the blowing snow aerosol particle source and the snowpack molecular bromine source together in GEOS-Chem increases model skill in simulating Arctic reactive bromine events. Our global chemical model improvements should improve prediction of the effect of climate change on Arctic reactive bromine levels and help assess their implications for ozone depletion and mercury deposition.
    • UAF's light-duty vehicle fleet lifecyle, maintenance costs and composition: ordinary least square regression and panel data analysis

      Hix, Edward R.; Wright, Christopher; Baek, Jungho; Little, Joe; Goering, Greg; Platt, Nathan (2020-08)
      The University of Alaska Fairbanks maintains a vehicle fleet for use by its staff, faculty, and students. Given the multifaceted needs of the campus and the impact that the harsh subarctic climate can have on vehicles, management of the fleet to meet the needs of its users is a complex task. One method UAF uses to manage the cost of the fleet is to extract the depreciation expense from each fleet vehicle into a non-interest bearing recharge account to eventually purchase its replacement. While several reviews have been conducted regarding the management of this fleet, a gap in research involves analysis of cost of this fleet over its lifecycle. This study examined the effects of fleet vehicle lifecycle extension beyond the predetermined 10-year useful life at UAF. Three novel datasets were created from UAF Facilities Services' archival maintenance work order data: a vehicle dataset, work order dataset, and a panel dataset. Ordinary least squares regression methods were used to examine the impact of model year on a vehicle's nominal purchase price and the impact of vehicle specification on real purchase price. Fixed and random effects panel methods were used to examine the impact of vehicle specification and vehicle age on maintenance costs. The effects of extending the fleet lifecycle from ten to twenty-years on maintenance and operational cost were estimated. Population dynamics models estimated the impact of the ten year lifecycle extension on the replacement fund. The results of this study suggested increasing vehicle lifecycles by ten years increased operating, maintenance, and replacement costs and effectively reduced the replacement fund purchasing power. The extension of vehicle lifecycles resulted in continually increasing rental rates and ultimately to the insolvency of the replacement fund.
    • Uncertainty quantification in unconventional reservoirs using conventional bootstrap and modified bootstrap methodology

      Okoli, Chukwuemeka; Awoleke, Obadare; Goddard, Scott; Ahmadi, Mohabbat (2020-12)
      Various uncertainty quantication methodologies are presented using a combination of several deterministic decline curve analysis models and two bootstrapping algorithms. The bootstrapping algorithms are the conventional bootstrapping method (CBM) and the modied bootstrapping method (MBM). The combined deterministic-stochastic combination models are applied to 126 sample wells from the Permian basin. Results are presented for 12 to 72 months of production hindcast given an average well production history of 120 months. Previous researchers used the Arps model and both conventional and modied bootstrapping with block re-sampling techniques to reliably quantify uncertainty in production forecasts. In this work, we applied both stochastic techniques to other decline curve analysis models∎namely, the Duong and the Stretched Exponential Production Decline (SEPD) models. The algorithms were applied to sample wells spread across the three main sub-basins of the Permian. A description of how both the deterministic and stochastic methods can be combined is provided. Also, pseudo-codes that describes the methodologies applied in this work is provided to permit readers to replicate results if necessary. Based on the average forecast error plot in the Permian Basin for 126 active wells, we can also conclude that the MBM-Arps, CBM-Arps, and MBM-SEPD combinations produce P50 forecasts that match cumulative production best regardless of the sub-basin and amount of production hindcast used. Regardless of concerns about the coverage rate, the CBM-Arps, MBM-Arps, CBM-SEPD, and MBMSEPD algorithm combinations produce cumulative P50 predictions within 20% of the true cumulative production value using only a 24-month hindcast. With a 12 month-hindcast, the MBM-Arps combined model produced cumulative P50 predictions with a forecast error of approximately 20%. Also, the CBM-SEPD and MBM-SEPD models were within 30% of the true cumulative production using a 12- month hindcast. Another important result is that all the deterministic-stochastic method combinations studied under-predicted the true cumulative production to varying degrees. However, the CBM-Duong combination was found to severely under-predict cumulative production, especially for the 12-month hindcast. It is not a suitable model combination based on forecast error, especially when hindcast fractions on the low end of the spectrum are used. Accordingly, the CBM- Duong combination is not recommended, especially if production history of no more than 24 months is available for hindcasting. As expected, the coverage rate increased, and the forecast error decreased for all the algorithm combinations with increasing hindcast duration. The novelty of this work lies in its extension of the bootstrapping technique to other decline curve analysis models. The software developed can also be used to analyze many wells quickly on a standard engineering computer. This research is also important because realistic estimates of reserves can be estimated in plays like the Permian basin when uncertainty is correctly quantied.
    • Understanding permafrost dynamics and geohazards with a terrain-cryofacies approach

      Stephani, Eva; Shur, Yuri; Doré, Guy; Darrow, Margaret; Kanevskiy, Mikhail (2021-12)
      The Arctic and its permafrost terrain are inherently dynamic, complex, and sensitive environments. Understanding the past and current changes occurring in these systems is key in predicting future variations, including the response of permafrost to climate change, and to terrain modifications resulting from natural processes or anthropogenic activities. This study contributes to advance our understanding of permafrost dynamics in varying permafrost environments of northern Alaska and northwestern Canada using a terrain-cryofacies approach. This unique approach helps to increase our understanding of permafrost dynamics from the site-specific scale to over extended areas by recognizing linkages between terrain and subsurface properties, and by identifying similar terrain units in remote sensing analysis. In the Colville River Delta (Alaska), our terrain-cryofacies study integrated data from 79 boreholes with a remote sensing analysis to evaluate the temporal changes in the Nigliq channel positions from 1948 to 2013 and the related permafrost dynamics. Most land cover changes occurred as land exposition (64%), whereas about 36% of the total changes were classified as eroded. The erosion of the older terrain units from the floodplain toposequence, such as the inactive-floodplain cover deposits, implied ground loss volumes of about one-fifth of soil solids and four-fifths of ground ice. Along this channel, we also identified the typical configuration and properties of taliks and cryopegs, as well as subsequent epigenetic permafrost growth. We found that the active channel was underlain by closed taliks, rather than through taliks and thus did not penetrate the entire layer of permafrost connecting supra- and sub-permafrost groundwater. A cryopeg connected to the active channel talik was identified from borehole data in the adjacent terrain units that developed following channel migration. We estimated the likelihood of encountering such taliks and cryopegs over extended areas. The terrain-cryofacies approach was also applied to understand permafrost dynamics of hillslope thermokarst located in multiple ecoregions of northern Alaska and northwestern Canada, including areas affected by interactions with infrastructure. Six features were studied through the combination of field-based and remote sensing methods, whereas 150 others were assessed solely by remote sensing. Studies along a pipeline indicated that embankment construction led to an increase in the active layer thickness, reaching the underlying ice-rich intermediate layer, and causing thaw settlement. This formed a thermokarst-ditch that facilitated channelization of cross-drainage water, and thermal erosion of the ice-rich permafrost that became affected by thermal denudation and caused a retrogressive thaw slump (RTS). The RTS later selfstabilized mainly due to the lateral discontinuity of massive ice (i.e., ice wedge) and the low-relief terrain. We suggested approaches to develop adaptation strategies for infrastructure at risk of RTS based on: these findings and conditions that favor or limit RTS growth by local feedbacks; considering the interaction patterns that we identified between RTS and infrastructure; and the main destabilization processes that we highlighted by terrain units. Further research is necessary, however, and must include testing potential mitigation techniques at multiple sites with monitoring programs to assess the variability in performance with respect to site-specific conditions.
    • Understanding the outcomes focused management production process: meta-analysis of the relationship between activities, settings, and the benefits of recreation participation

      Diamond, Kimberly; Fix, Peter J.; Peterson, Jen; Coker, Robert (2021-08)
      The 1958 Outdoor Recreation Resources Review Commission, through a 1962 report, tasked federal agencies to inventory supply and demand for outdoor recreation participation. Recreation managers are progressively focusing on demand for the beneficial outcomes of recreation, but have struggled to structure planning and management models to guide decisions that optimize recreationists' ability to attain desired benefits. The Outcomes Focused Management (OFM) framework links benefits to specific activity and setting combinations, giving managers a functional role in the process of benefit production. Past studies examining the OFM's activity-setting-benefit relationship reported weak results, but suggest activity is a stronger predictor of benefit attainment than setting. A better understanding of how activity and setting inputs affect recreationists' ability to realize desired benefits is needed for continued implementation of OFM, with the aim of improving attainment rates of positive recreation outcomes. This study used meta-analytic techniques with data compiled from 16 OFM studies to replicate and expand on published work. With the goal of improving the activity-setting-benefit model, this study introduced two predictor variables, previous visitation and visitors' residential proximity to the site, controlled for the desirability of the benefit, and re-conceptualized the setting variable by testing whether study site is a better predictor of benefit attainment than different settings within a site. Two-way analysis of variance tests measured the dependence of 40 personal (PER) and household, community, economic, environmental benefits (HCEE) on activity participation and setting, using effect sizes and significance levels to compare seven models. This meta-analysis reciprocated findings of a 2004 study, failing to offer definitive evidence of linkages among recreation opportunities in the context of the models tested. Benefit items exhibiting relatively higher sensitivity to activity and setting inputs were 1) "Restore my body from fatigue" (PER), 2) "Improved respect for privately owned lands" (HCEE), 3) "Increased self-confidence" (PER), and 4) "Greater respect for private property and local lifestyles" (PER). Suggestions for future OFM studies and research on the activity-setting-benefit relationship are made, in addition to a summary of potential implications for OFM based on the findings of this study.
    • Using ultraconserved elements to estimate gene flow between Asian and North American avian taxa

      Spaulding, Fern R.; Winker, Kevin; Drown, Devin; Takebayashi, Naoki (2021-08)
      Alaska is a prime location to study avian speciation, divergence, and gene flow. The area of Beringia, the region extending from the Russian Far East across the Bering Sea though Alaska, has historically experienced periodic cycles of glaciation. These cyclic fluctuations in climate have had genetic consequences on the organisms that reside in this region. In this thesis, I examine the genetic relationships between Old World and New World lineages of Holarctic avian taxa. Specifically, I examine how intercontinental movements (i.e., gene flow) have shaped divergence, speciation, and phylogenetic relationships in several key lineages of Holarctic waterbirds. Using ultraconserved elements (UCEs) as a molecular marker, I implemented population genomic analyses to better understand divergence, speciation, and levels of gene flow among several Beringian waterbird lineages. In the first of the two studies, I examine mitogenomic and nuclear DNA in a small clade of ducks with historically uncertain relationships and species limits: the Eurasian common teal (Anas crecca crecca), the North American green-winged teal (Anas crecca carolinensis), both seasonal migrants, and the sedentary Aleutian green-winged teal (Anas crecca nimia). In addition to the three subspecies of green-winged teal, I included the South American yellow-billed teal (Anas flavirostris), a close relative of Anas crecca, to fully resolve this teal complex. Phylogenetic relationships using nuclear DNA showed the three subspecies of Holarctic greenwinged teal (Anas crecca spp.) to form a polytomous clade with A. flavirostris being sister to this clade. However, mitogenomic data show a different phylogeny, with A. c. carolinensis being sister to A. flavirostris, while A. c. crecca was sister to A. c. nimia. Evidence for divergence with gene flow was present in all three pairwise contrasts of our demographic analyses. Given prior work, gene flow was expected among the Holarctic taxa, but gene flow between North American A. c. carolinensis and South American A. flavirostris, albeit low, was not. Three geographically oriented modes of divergence are likely involved: heteropatric speciation between A. c. crecca and A. c. nimia, parapatric speciation between A. c. crecca and A. c. carolinensis, and (mostly) allopatric speciation between A. c. carolinensis and A. flavirostris. In the second study, I applied genomic methods to estimate gene flow and the magnitude of intercontinental movements occurring in vector species of avian influenza. Many seasonally migratory birds that are vectors of avian influenza (i.e., waterbirds) fly between Eurasia and North America every year, but accurate numbers of birds crossing between continents have yet to be adequately determined. Vector species' movements are difficult to quantify, but population genomics can provide baseline rates of these intercontinental movements. My study examined the following species: northern pintail (Anas acuta), mallard (Anas platyrhynchos), greater scaup (Aythya marila), common eider (Somateria mollissima), green-winged teal (Anas crecca crecca - A. c. carolinensis), long-tailed duck (Clangula hyemalis), Eurasian and American wigeons (Mareca penelope - M. americana), and common and Wilson's snipe (Gallinago gallinago - G. delicata). Many of these species are also important as subsistence food for Alaskans, increasing the risk of direct bird-to-human avian influenza exposure. In addition to providing a robust intercontinental framework of movements (i.e., gene flow) for these vector species in the natural virus transport system, I examine them in the context of the importance of each species in Alaskan diets to understand the relative risk of these taxa to human Eurasian-origin avian influenza exposure. The inferred rates of movement between these populations varies greatly among lineages. These taxon-based intercontinental movement rates and relative risk rankings should help in modeling, monitoring, and mitigating the impacts of intercontinental host and avian influenza movements.
    • Utility of trace element studies for improving our understanding of geochemical processes within the arctic ocean environment

      Bolt, Channing; Aguilar-Islas, Ana; Rember, Robert; Reynolds, Jennifer; Rivera-Duarte, Ignacio; Simmons, Harper (2021-05)
      The Arctic Ocean is a dynamic region undergoing rapid change. Sea ice and meteoric water are intrinsic components of the Arctic environment that play key roles in its ecosystem, including the distributions and cycling of trace elements throughout the pan-Arctic Ocean. Meteoric water (e.g., rivers and snow deposition) contributes to the input of trace elements to surface waters, while sea ice dynamics contribute to the transport of these constituents across Arctic basins. Trace element distributions can provide insights into Arctic processes. The focus of Chapter One is on particulate (>0.2 μm) trace elements in Arctic pack ice, associated snow, and underlying surface waters collected from September-October 2015 during the US GEOTRACES Western Arctic cruise (GN01). This late-season pack ice provides a snapshot of sea ice characteristics in regions near the North Pole, within the Makarov and Canada Basins, and can estimate the impact melting sea ice may have on particulate trace element inputs to Arctic waters. Chapter Two presents on the utility of dissolved barium (dBa), a bio-intermediate element of lithogenic origin, as a tracer of meteoric water throughout the Siberian Arctic Ocean. Samples for Chapter Two were collected during the 2018 Nansen and Amundsen Basin Observatory System. The distribution of dBa in this region may provide useful insights into important shelf processes, such as tracing shelf waters along continental slopes. In Chapter 3, additional spatiotemporal geochemical parameters (δ¹⁸O and salinity) are considered alongside dBa to model how Arctic water mass fractions (meteoric, sea ice melt, and Atlantic waters) changed between 2013, 2015, and 2018 within the Siberian Arctic Ocean. This dissertation contributes to the understanding of Arctic Ocean processes through the application of trace element studies and highlights the usefulness of combining tracers to better understand this dynamic environment.
    • Vertebrate ichnology and paleoenvironmental associations of Alaska's largest dinosaur track site in the cretaceous Cantwell Formation (Maastrichtian) of Denali National Park and Preserve

      Stewart, Dustin G.; Druckenmiller, Patrick; Fowell, Sarah; McCarthy, Paul (2020-10)
      The Upper Cretaceous Cantwell Formation in Denali National Park and Preserve (DENA) has recently been recognized as a major high latitude dinosaur track-bearing unit in Alaska. The abundant trace fossil record of the Cantwell Formation, which represents a diverse community of avian and non-avian dinosaurs, compliments the body fossil record of the state's other major dinosaur-producing unit, the Prince Creek Formation of northern Alaska. However, research in the Cantwell Formation is still in its infancy due to its wide aerial extent and remoteness, and many questions remain concerning the temporal, ichnological, and paleoenvironmental relationships of the formation. Here I describe and analyze the largest known single track site currently known in DENA and all of Alaska -- a football field-sized outcrop named the Coliseum. This site is composed of 65+ meters of vertical section, with laterally extensive fine- to medium-grained sandstone, indurated mudstone, fissile shale, and bentonite. Trace fossils at the Coliseum include true tracks, undertracks, natural casts, and trackways that vary in their preservation from eroded, trampled surfaces to individual prints with skin impressions. The tracks were documented via handheld and UAV-assisted photogrammetry, enabling a large-scale 3-dimensional mapping of the Coliseum. Facies analysis of the site reveal the tracks were formed on crevasse splay and overbank deposits within a fluvial floodplain. U-Pb dating of zircons collected from a bentonite horizon return an age of 69.3±0.9 Ma (early Maastrichtian), improving the temporal constraints of the formation and revealing one of the youngest ages of deposition for the formation. Several new dinosaurian ichnotaxa previously unrecognized from the formation are described, revealing the presence of large-bodied ornithopods, ceratopsids, and non-avian and avian theropod trackmakers. The Coliseum provides a snapshot of an ancient forested environment inhabited by a diverse dinosaurian community deposited in the Late Cretaceous paleo-Arctic.
    • Vetting model and satellite-based estimates of regional scale carbon exchange at northern high latitudes using solar-viewing infrared spectroscopy

      Jacobs, Nicole; Simpson, William R.; Euskirchen, Eugénie S.; Guerard, Jennifer; Maxwell, David A. (2021-08)
      Carbon exchange in the Boreal Forest and its response to a warming climate is a critical process that needs to be understood for more accurate predictions of climate change. Therefore, we established a ground-based long-term monitoring site at the University of Alaska Fairbanks in Fairbanks, Alaska, USA (64.859°N, 147.850°W) operating a solar-viewing Bruker EM27/SUN Fourier transform infrared spectrometer (FTS). This instrument measures vertically integrated column abundances of carbon dioxide (CO₂), methane (CH₄), and carbon monoxide (CO), termed Xgas, i.e., XCO₂. These measurements are directly comparable to satellite-based measurements, for which these ground-based observations provide validation data. Measurements of XCO₂ and XCH₄ have to be extremely precise because variability in atmospheric columns of CO₂ and CH₄ is often less than 1% of the background levels of these long-lived gases. Therefore, the observations in Fairbanks were carefully vetted through comparisons of results from two retrieval algorithms applied to the same observed spectra, comparisons of observations from two EM27/SUN FTS operating side-byside, and comparisons between an EM27/SUN FTS and measurements from a Bruker IFS125HR in the Total Carbon Column Observing Network (TCCON) at Caltech, Pasadena, California. These data are all collected over a period of about 4.5 years. Comparisons of retrieval methods indicate that the results are tightly correlated, but there are offsets that could be corrected with an appropriate scaling factor. Observed biases between two colocated EM27/SUN FTS were in agreement within instrument precision. Biases between the EM27/SUN and TCCON retrievals at Caltech are larger and more variable than biases between the two EM27/SUN FTS in Fairbanks, which may be partially explained by differences in spectral resolution. These biases are also similar to those reported in previous studies. Vetted Fairbanks observations are used in combination with those from two TCCON sites in the Boreal Forest, East Trout Lake, Saskatchewan, Canada (54.354°N, 104.987°W) and Sodankylä, Finland (67.367°N, 26.631°E), to evaluate quality control methods and bias in XCO₂ from the NASA Orbiting Carbon Observatory 2 (OCO-2). This study yielded alternative quality control thresholds and bias correction, tailored to Boreal Forest regions that allow for increased data throughput and reduced seasonality in bias over northern high latitude regions. In particular, increased data throughput in spring and autumn months made it possible to measure XCO₂ seasonal cycles using satellite-based measurements. In this analysis, we found that the Asian Boreal Forest region stood out as having the largest seasonal amplitude and earliest seasonal drawdown of any region. There is also a pronounced west-to-east gradient of increasing seasonal amplitude and earlier seasonal drawdown across the Eurasian continent. Comparisons with two independent global CO₂ models are good, showing high correlation and spatial agreement. Analysis of modeled (GEOS-Chem) surface contact tracer contributions reveals that the largest seasonal amplitudes occur in regions that have the largest contributions from land-based surface contact tracers with 15 or 30 day atmospheric lifetimes, suggesting that accumulations of CO₂ exchanges during atmospheric transport on approximately monthly timescales play an important role in shaping observed XCO₂ seasonal cycles in northern high latitude regions. Furthermore, surface contact tracer contributions from land were more correlated with XCO₂ seasonal amplitude than estimates of total annual fluxes or seasonal amplitudes of flux estimates within a region, emphasizing the importance of understanding the effects of atmospheric transport when interpreting observations of XCO₂.
    • Western Gwich'in classificatory verbs

      Bushey, Scott T.; Tuttle, Siri; Peter, Hishinlai'; Vajda, Edward (2021-05)
      One of the many challenges faced by learners and teachers of Gwich'in, an endangered Athabascan or Dene language of Alaska and Canada, is a lack of instructional material for classificatory verbs. These verbs classify states and actions, such as lie, carry, and fall, by perceived qualities, such as cloth-like and stick-like, that indicate how and with which nominal entities the state or action takes place. For students of Gwich'in and other Dene languages, such as Navajo and Koyukon, classificatory verbs are an important grammar objective when included in the curriculum. Recognition and production of classificatory verbs is a main objective for students in the second year of the UAF Gwich'in class. Classificatory verb words are also present in vocabulary learned from the first year, such as gishreiin'ąįį "it's sunny" and OBJ naltsuu "I'm wearing OBJ [upper-body garment]". In this thesis I present a documentary, descriptive study of classificatory verbs and their qualities in modern spoken Gwich'in. The first goal of the study is to document examples of Gwich'in classificatory verbs in conversational and narrative discourse, and the second is to describe their morphosemantic properties and behavior. The third goal is to accomplish these documentary and descriptive aims in a way that can be adapted readily to the needs of not only linguists, but also Gwich'in language learners and teachers. Informed by previous documentary and descriptive work on classificatory verbs in other Dene languages, I attempt to provide a similarly useful text for Gwich'in, reconciling several competing nomenclatures and illustrating the relationship between classificatory verb theme sets, such as "carry", and semantic classes of verb stems, such as "animate", in a broad range of modal and aspectual contexts. Although this thesis is intended primarily as a reference work for learners and teachers, it also provides a resource for linguists comparing Gwich'in classificatory verbs with those in related Dene languages. The classificatory verb data in this thesis is drawn from a body of Gwich'in class notes and assignments, well as transcribed Gwich'in oral literature and consultation with a native speaker of the language. Classroom instruction took place between 2018 and 2020 at the University of Alaska Fairbanks and emphasized spoken language production with communicative aims. In addition to work from the Gwich'in language classroom, limited native speaker consultation regarding classificatory verbs was also conducted in February 2020. The third data source for this study is the rich body of narrative discourse available in the form of transcribed oral literature. These works record Gwich'in traditional narrative knowledge, lore, and history across a broad range of topics, in which classificatory verbs may be readily encountered and examined. Having drawn from these three pools of data, this thesis describes the morphosemantic qualities of Gwich'in classificatory verbs while considering the available data on other Dene languages and considers actual and potential application of this data in the language classroom.