• Oblique impact cratering: A comparison of low-velocity experiments to high-velocity experiments

      Hessen, Katie K.; Hessen, Robert; Dean, Ken; West, Michael; Chappelow, John; Christensen, Douglas (2008-12)
      Previous impact cratering experiments performed by Gault and Wedekind (1978), used high-velocity impactors (~1 km/s to 7 km/s) to quantify how impact angle affects crater morphology and ejecta pattern. Low velocity (144 m/s to 260 m/s) impact experiments were conducted in a vacuum chamber with a basaltic sand target material and impact angles ranging from 0.5° to 90° (vertical) at the Impact Cratering Laboratory at the University of Tokyo Kashiwa. The crater morphology and ejecta distribution from low velocity impacts are then compared to results from the higher velocity projectiles. When adjustments are made to the low-velocity measurements to account for differences in velocity, the displaced mass ratio follows a sinθ distribution, as is seen in the high- velocity experiments. In the low-velocity experiments, asymmetric ejecta is present at slightly higher impact angles. The presence of an uprange forbidden zone occurs at the same impact angle (20°) in both sets of experiments. The most striking difference between the two sets of experiments is the complete lack of a downrange forbidden zone in all of the low-velocity experiments. With the exception of the very lowest impact angles, these low-velocity oblique impact experiments yield similar changes in crater characteristics with varying impact angles to the previous high-velocity experiments.
    • Observable effects of attention, posture, ergonomics and movement in the classroom

      Healy, Joanne; Bult-Ito, Abel; Anahita, Sine; Charles, Walkie; Irish, Joel; Kaden, Ute (2014-05)
      Two studies related to student attention, posture, school ergonomics, student behavior (leaning, standing up, and moving), and learning engagement were conducted in Alaska. The Children's Postural Improvement Study (CPIS) looked at the observable effects of two interventions on attention. In the Classroom Environmental Study (CES) a baseline ergonomic survey compared observed student behavior and classroom arrangements. The purpose of the CPIS was to investigate the effects of a postural education program, consisting of five 30-minute instructional sessions, as compared to a nutritional intervention at two elementary schools and its effect on attention. Three quantitative tools measured attention, the post-Partial Vanderbilt ADHD Teacher and Parent rating scales and pre- and post-math fluency tests. Qualitative measures included pre- and postintervention photographs, daily comments from students after the lesson, and post open-ended-question student and teacher surveys. Based on the post-surveys, participants valued their good posture and made concentrated efforts to improve it. Quantitative results of this postural study revealed no correlation between posture and attention. The follow-up CES examined the current state of furniture in 78 classrooms and pedagogical practices in regard to student movement and learning engagement in eight fourth-grade classrooms in three elementary schools. Two-way ANOVA revealed a significant school effect for leaning and significant classroom nested within school effects for leaning, standing up, and moving. Classroom sketches were coded to examine movement and posture. No significant difference for desk clusters by grade, or by school using the Chi-squared test were found, but there was a significant difference comparing the seating relationship to instructional delivery by grade and by school. Recommendations for future research and changes within Schools of Education and school districts to improve posture and learning engagement include: adjust current students' chairs and desks to meet their ergonomic needs; raise awareness of and inform pre-service, current teachers, students, and parents about ergonomic health concepts; encourage teachers to move around the classroom while instructing to engage students as they track the teacher's movement; and limit instructional periods to 20 minutes or less to allow for student movement breaks.
    • Observations and generation mechanisms of slow-mode waves in the magnetosheath

      Yan, Ming; Lee, Lou; Craven, John; Hawkins, Joseph; Sentman, Dave; Watkins, Brenton (1995)
      The interaction of solar wind with the geomagnetic field leads to the formation of the bow shock, magnetosheath, and magnetopause. Magnetohydrodynamic (MHD) slow-mode structures with a plasma density enhancement and magnetic field depression have been observed to appear frequently in the inner magnetosheath. In addition, the slow-mode structures usually consist of slow-mode waves with a smaller length scale. These slow-mode structures and waves are studied in this thesis through satellite observations and numerical simulations. We find, through satellite observations, that some of the slow-mode structures are associated with Alfven waves in the solar wind. On the other hand, simulations show that slow-mode waves are generated through the interactions between the bow shock and interplanetary shocks, magnetosonic waves, rotational discontinuities, or Alfven waves. The generated slow-mode waves stay in the inner magnetosheath for a long time (about 15 minutes) before the wave energy is convected away tailward. Of particular importance are the interactions between the bow shock and interplanetary rotational discontinuities or Alfven waves. These interactions generate a region with an enhanced plasma density and depressed magnetic field, which is very similar to the slow-mode structures observed in the inner magnetosheath. Based on observations and simulations, it is suggested that the interactions of various types of solar wind fluctuations with the bow shock may lead to the frequent appearance of slow-mode structures and waves in the inner magnetosheath. The generated slow-mode structures have strong pressure variations, and may impinge on the magnetopause as strong pressure pulses.
    • Observations Of Metal Concentrations In E-Region Sporadic Thin Layers Using Incoherent-Scatter Radar

      Suzuki, Nobuhiro; Watkins, Brenton (2006)
      This thesis has used incoherent-scatter radar data from the facility at Sondrestrom, Greenland to determine the ion mass values inside thin sporadic-E layers in the lower ionosphere. Metallic positively-charged ions of meteoric origin are deposited in the earth's upper atmosphere over a height range of about 85-120 km. Electric fields and neutral-gas (eg N2, O, O2) winds at high latitudes may produce convergent ion dynamics that results in the re-distribution of the background altitude distribution of the ions to form thin (1-3 km) high-density layers that are detectable with radar. A large database of experimental radar observations has been processed to determine ion mass values inside these thin ion layers. The range resolution of the radar was 600 meters that permitted mass determinations at several altitude steps within the layers. Near the lower edge of the layers the ion mass values were in the range 20-25 amu while at the top portion of the layers the mass values were generally in the range 30-40 amu. The numerical values are consistent with in-situ mass spectrometer data obtained by other researchers that suggest these layers are mainly composed of a mixture or Mg +, Si+, and Fe + ions. The small tendency for heavier ions to reside at the top portion of the layers is consistent with theory. The results have also found new evidence for the existence of complex-shaped multiple layers; the examples studied suggest similar ion mass values in different layers that in some cases are separated in altitude by several km.
    • Oceanic emissions of sulfur: Application of new techniques

      Jodwalis, Clara Mary; Benner, Richard L. (1998)
      Sulfur gases and aerosols are important in the atmosphere because they play major roles in acid rain, arctic haze, air pollution, and climate. Globally, man-made and natural sulfur emissions are comparable in magnitude. The major natural source is dimethyl sulfide (DMS) from the oceans, where it originates from the degradation of dimethysulfonioproprionate (DMSP), a compound produced by marine phytoplankton. Global budgets of natural sulfur emissions are uncertain because of (1) the uncertainty in the traditional method used to estimate DMS sea-to-air flux, and (2) the spatial and temporal variability of DMS sea-to-air flux. We have worked to lessen the uncertainty on both fronts. The commonly used method for estimating DMS sea-to-air flux is certain to a factor of two, at best. We used a novel instrumental technique to measure, for the first time, sulfur gas concentration fluctuations in the marine boundary layer. The measured concentration fluctuations were then used with two established micrometeorological techniques to estimate sea-to-air flux of sulfur. Both methods appear to be more accurate than the commonly used one. The analytical instrument we used in our studies shows potential as a direct flux measurement device. High primary productivity in high-latitude oceans suggests a potentially large DMS source from northern oceans. To begin to investigate this hypothesis, we have measured DMS in the air over northern oceans around Alaska. For integrating and extrapolating field measurements over larger areas and longer time periods, we have developed a model of DMS ocean mixing, biological production, and sea-to-air flux of DMS. The model's main utility is in gaining intuition on which parameters are most important to DMS sea-to-air flux. This information, along with a direct flux measurement capability, are crucial steps toward the long-term goal of remotely sensing DMS flux. A remote sensing approach will mitigate the problems of spatial and temporal variability. The new developments in methodology, field sampling, and modeling put forth in this thesis are tools we have used to better understand and quantify sulfur gas emissions from northern oceans, which appear to be a significant source of sulfur to the global atmosphere.
    • Ogotoruk Creek Botanical Investigations Cape Thompson, Alaska

      Viereck, L.A.; Johnson, R.E.; Melchior, H.R. (Department of Biological Sciences, University of Alaska, 1960-12)
      Botanical investigations of the Cape Thompson - Ogotoruk Creek region of northwest Alaska were initiated in May, 1959 by the University of Alaska under contract with the United States Atomic Energy Commission (Contract No. AT (04 -3 ) - 310). The first summer's field work was largely exploratory and descriptive in nature and included a species inventory of the vascular plants, mosses, and lichens; a qualitative description of the main vegetation types in Ogotoruk Valley; and a preliminary mapping of the vegetation types within the valley. The results of the first summer's field work and winter visits have been partially reported in two reports: Ogotoruk Valley Botanical Project, December, 1959 Report, and the Phase II Interim Pinal Report, Ogotoruk Valley Botanical Project, June, 1960. For brevity, these will be referred to as the December, 1959 Botanical Report, and the June, 1960 Botanical Report. Materials reported in these earlier reports will not be repeated in this December, 1960 report. Botanical investigations were continued during the summer and fall of 1960. The objectives of the 1960 field season were as follows: 1. To measure the frequency, cover, and synthetic features of the main vegetation types in Ogotoruk Valley. 2. To establish control vegetation plots in areas outside the potential blast and fallout area and to extend our understanding of the vegetation of the northwestern Alaska Coast. 3. To complete records of species occurrence in the area by continuing plant collections and identifications. 4. To revise and complete the vegetation map of the area. 5. To continue seed germination studies on certain species. 6. To commence palynological studies of bog and lacustrine sediments. 7. To initiate studies on some of the ecological problems in the Ogotoruk Valley area. a. to understand the relationship between permafrost, annual freezing-thawing cycles, and plant distribution. b. to understand the inter-relationships of the activities of the arctic ground squirrel and vegetation in the valley. Preliminary results of the 1960 field work and additional information from the 1959 season are included in this report.
    • Oil and wildfire effects on nutrient cycling and microbial diversity in subarctic mineral soils

      Garron, Jessica I.; Braddock, Joan; Valentine, David; Lindstrom, Jon (2007-05)
      In 1976 crude oil was experimentally spilled on a plot near Fairbanks, Alaska to mimic an oil pipeline spill. The plot and surrounding area were further disturbed by wildfire in 2004. Although the fire burned organic matter on the plot surface, substantial subsurface oil remained. After the fire, soil samples from oiled/burned, burned, and control plots were collected to evaluate the effects of disturbance on nutrient cycling and soil bacterial communities. Samples were analyzed for total nitrogen (N), soil carbon (C) and N mineralization, N fixation, total bacterial diversity (16S rDNA), and functional genetic diversity (nifH). Inorganic N was low in all soil types. In control and burned soils there was net N mineralization, but in oiled/burned soils there was significant N immobilization. Carbon mineralization was much higher in oiled/burned soils than control or burned soils. While the highest N fixation potential was measured in oiled/burned soils, the diversity of the N-fixing bacterial community in those soils was about the same as that of the control. For 16S rDNA, diversity was higher in control and burned soils than in oiled/burned soils. Overall, the type of disturbance and the length of time since disturbance both affected microbial function and diversity
    • On the frontal ablation of Alaska tidewater glaciers

      McNabb, Robert Whitfield; Hock, Regine; Bueler, Edward; Motyka, Roman; Pettit, Erin; Truffer, Martin (2013-08)
      Sea level rise is a major problem that society will face in the coming century. One of the largest unknown components of sea level rise is frontal ablation (the sum of mass loss through calving and subaqueous melting) from glaciers and ice sheets. Using estimates of ice thickness, rates of glacier length change, and glacier velocities, we present a record of frontal ablation over the period 1985-2012 for 20 Alaska tidewater glaciers. We also present a new method for estimating ice thickness by solving the continuity equation between adjacent flowlines. Because of the wealth of data available, we apply this method to Columbia Glacier, Alaska. The mean ice thickness and volume of Columbia Glacier were approximately halved over the period 1957-2007, from 281 m to 143 m, and from 294 km�_ to 134 km�_, respectively. Using bedrock slope and considering how waves of thickness change propagate through the glacier, we conclude that the rapid portion of this tidewater glacier's retreat is likely nearing an end. We present a 64 year record of length change for 50 Alaska tidewater glaciers, over the period 1948-2012. Most (31) glaciers retreated over the period. Examination of the onset of glacier retreats indicates a correlation between high summer sea surface temperature and the triggering of retreat. Finally, we present a 27 year record of surface velocity for 20 Alaska tidewater glaciers derived from Landsat imagery. Surface velocities vary by as much as 80% throughout the year, indicating that using measurements from one time of year may bias estimates of frontal ablation. The total mean rate of frontal ablation for these 20 glaciers over the period 1985-2012 is 16.2 � 6.5 Gt a����_. Extending this to the remaining 30 Alaska tidewater glaciers yields an estimate of frontal ablation of 18.3 � 7.3 Gt a����_, approximately 50% of the climatic mass balance of the region. This indicates the important, non-negligible role frontal ablation can play in regional mass balance, even where tidewater glaciers cover a small fraction of the total area.
    • On the Klein-Gordon equation originating on a curve and applications to the tsunami run-up problem

      Gaines, Jody; Rybkin, Alexei; Bueler, Ed; Nicolsky, Dmitry (2019-05)
      Our goal is to study the linear Klein-Gordon equation in matrix form, with initial conditions originating on a curve. This equation has applications to the Cross-Sectionally Averaged Shallow Water equations, i.e. a system of nonlinear partial differential equations used for modeling tsunami waves within narrow bays, because the general Carrier-Greenspan transform can turn the Cross-Sectionally Averaged Shallow Water equations (for shorelines of constant slope) into a particular form of the matrix Klein-Gordon equation. Thus the matrix Klein-Gordon equation governs the run-up of tsunami waves along shorelines of constant slope. If the narrow bay is U-shaped, the Cross-Sectionally Averaged Shallow Water equations have a known general solution via solving the transformed matrix Klein-Gordon equation. However, the initial conditions for our Klein-Gordon equation are given on a curve. Thus our goal is to solve the matrix Klein-Gordon equation with known conditions given along a curve. Therefore we present a method to extrapolate values on a line from conditions on a curve, via the Taylor formula. Finally, to apply our solution to the Cross-Sectionally Averaged Shallow Water equations, our numerical simulations demonstrate how Gaussian and N-wave profiles affect the run-up of tsunami waves within various U-shaped bays.
    • On using numerical sea-ice prediction and indigenous observations to improve operational sea-ice forecasts during spring in the Bering Sea

      Deemer, Gregory Joseph; Bhatt, Uma; Eicken, Hajo; Hutchings, Jennifer; Danielson, Seth (2015-05)
      Impacts of a rapidly changing climate are amplified in the Arctic. The most notorious change has come in the form of record-breaking summertime sea-ice retreat. Larger areas of open water and a prolonged ice-free season create opportunity for some industries, but bring new challenges to indigenous populations that rely on sea-ice cover for subsistence. Observed and projected increases in Arctic maritime activities require accurate sea-ice forecasts on the weather timescale, which are currently lacking. Motivated by emerging needs, this study explores how new modeling developments and local-scale observations can contribute to improving sea-ice forecasts. The Arctic Cap Nowcast/Forecast System, a research sea-ice forecast model developed by the U.S. Navy, is evaluated for forecast skill. Forecasts of ice concentration, thickness, and drift speed produced by the model from April through June 2011 in the Bering Sea have been investigated to determine how the model performs relative to persistence and climatology. Results show that model forecasts can outperform forecasts based on climatology or persistence. However, predictive skill is less consistent during powerful, synoptic-scale events and near the Bering Slope. Forecast case studies in Western Alaska are presented. Community-based observations from recognized indigenous sea-ice experts have been analyzed to gauge the prospect of using local observations in the operational sea-ice monitoring and prediction process. Local observations are discussed in the context of cross-validating model guidance, data sources used in operational ice monitoring, and public sea-ice information products issued by the U.S. National Weather Service. Instrumentation for observing sea-ice and weather at the local scale was supplied to key observers. The instrumentation shows utility in the field and may help translate the context of indigenous observations and provide ground-truth data for use by forecasters.
    • One health toxicology: expanding perspectives and methods to assess environmental contaminants

      Harley, John Robinson; O'Hara, Todd; Dunlap, Kriya; Duffy, Lawrence; Rea, Lorrie (2017-12)
      The discipline of One Health is founded on the principal that environmental health, animal health, and human health are interconnected. Although the field has been largely focused on zoonotic diseases, examining concepts such as toxicology under a One Health lens can offer a more holistic and preventative approach to research and implementation and, in particular, how fish-based diets may be involved with One Health outcomes. Here we present three general case studies that demonstrate new approaches to investigating One Health toxicology. In Chapter One we show how Arctic canids can be used as environmental sentinels for human health. We discuss three separate canid studies; in the first we find that Arctic foxes can act as sentinels of Arctic contaminants due to their foraging plasticity, in the second we examine the use of fish-fed sled dogs as a model for the effects of a fish-based diet on contaminants exposure and gene transcription, and in the third we develop the sled dog as a model for particulate matter air pollution in the Fairbanks North Star Borough. In Chapter Two we utilize the Steller sea lion, a nonmodel organism, as a sentinel for the effects of fish-based diet mercury exposure induced whole-genome changes in gene transcription (RNA-Seq). Using newly developed informatics tools we assemble a de novo transcriptome and examine large scale changes in gene expression related to mercury exposure and other One Health uses. This approach is extremely adaptable and has the potential to be applied across numerous non-model organisms and contaminants. We also applied a microbial mining algorithm to our RNA-Seq data and found evidence for a hemotropic Mycoplasma spp. in one of our samples. In Chapter Three we examine sources of mercury exposure for pregnant women from La Paz, Baja California Sur, Mexico. We found mercury concentrations to be generally low among the examined fish species and staple foods. While typical dietary assessments rely on recall surveys and questionnaires, we found that examining chemical biomarkers of diet including stable isotopes of carbon and nitrogen are critical in dietary risk assessment. Taken together these three investigations offer valuable lessons and techniques which can be applied to the field of One Health toxicology; especially to those fish diet based systems.
    • The ontogeny of hypoxic neuroventilation in the brainstem of the developing American bullfrog, Rana catesbeiana

      Buehner, Justin C.; Taylor, Barbara; Drew, Kelly; Harris, Michael; Duffy, Lawrence K. (2008-12)
      Isolated brainstem models have been used twice to examine the hypoxic neuroventilatory response (HnVR) in developing bullfrogs with varying results, leading me to question if the results of these two previous studies were physiologically relevant. Based on in vivo and in vitro observations, I hypothesized that buccal neuroventilation exhibits no ventilatory response to hypoxia in any developmental stage and that lung neuroventilation exhibits a biphasic hypoxic response in late metamorphic tadpoles and a neuroventilatory depression in juvenile bullfrogs and early metamorphic tadpoles. I tested this by using brainstems isolated from intact early and late metamorphic tadpoles and juvenile bullfrogs exposed to 20% O2 saturation in artificial cerebrospinal fluid. Neuroventilatory patterns were recorded from the facial and hypoglossal nerves using suction electrodes and burst frequency, and duration for buccal and lung bursts were examined in all developmental stages. Results confirmed my hypothesis for buccal neuroventilation across development and lung neuroventilation in juveniles, but not my hypothesis about lung neuroventilation in tadpoles. Therefore, the HnVR of developing bullfrogs consists of constant maintenance of neuroventilatory activity in early metamorphic tadpoles, a trend towards a biphasic neuroventilatory response in late metamorphic tadpoles, and ventilatory depression that is mediated centrally in juvenile bullfrogs.
    • Opportunistic Survey Data of Common Gull (Larus canus) and other detections in an Urban Environment, downtown Fairbanks, Interior Alaska during mid-May 2014

      Huettmann, Falk; Spangler, Mark (2014-05-17)
      This dataset presents a Common Gull (Mew Gull, Larus canus, Taxonomic Serial Number TSN 176832) survey data set for urban areas and stripmall parking lots (app. 300mx600m), super markets, fast food restaurants, gravel pits, small ponds and the riverside (Chena) in Fairbanks, interior Alaska located app. 120 miles south of the arctic circle. We did geo-referenced 50 point surveys and detections in a rapid assessment fashion. Some opportunistic data were also taken when cruising. Gull data included detection width to obtain correction factors. Data were geo-referenced with a GPS in decimal degrees (latitude and longitude, geographic datum of WGS84) collected in early breeding season, 17th of May in 2014 on a Saturday (regular shopping and business times in the U.S.) between 8.15 AM and 5 PM by driving opportunistically on public strip mall parking lots, domestic areas and other locations of relevance for gull presences and absences in the survey area (app. 200m radius). These non-intrusive citizen science car-based surveys result into a virtually unbiased data providing a representative snap shot in space and time for the study area. Stripmall parking lots near rivers represent a typical situation of where Common Gulls are found in an urban habitat during breeding season. We reported basic gull behaviour also. Some other bird species were recorded as well but not in great detail, e.g. American Wigeon, Lesser Scaup, Pigeon, White Crowned Sparrow, Swallow sp, Shorebirds sp, Mallard, Lesser Yellowleg, American Robin, Scaups sp., Common Raven, Bunting sp., Grassland birds, Northern Shoveler, Grebe sp., Dark-eyed Junco, Herring Gull, Grouse sp. Noteworthy are the higher abundances of planes and helicopters. The gull abundance seems to be driven by food items on the parking lot, e.g. provided by an adjacent fast food restaurant and by wetland areas nearby (e.g. Chena river and gravel pits) where the gulls find good conditions for nearby nesting. Gulls seem to be quite colonial. This survey is unique and contributes to multi-year baseline information relevant for gulls, ravens, urban subsidized predators (e.g. raptors) in the interior of Alaska. They are a simple but powerful snapshots in time and space and when put into an overall ecological context, e.g. as done with Geographic Information System (GIS) analysis. Some photos exist for visual information. The dataset is provided in MS Excel, consists of 144 rows and is less than 1MB in size.
    • Opportunistic Survey Data of Common Gull (Larus canus) and other detections in an Urban Environment, downtown Fairbanks, Interior Alaska during mid-May 2015

      Huettmann, Falk (2015-05-12)
      This dataset presents a Common Gull (Mew Gull, Larus canus, Taxonomic Serial Number TSN 176832) survey data set for urban areas and stripmall parking lots (app. 300mx600m), super markets, fast food restaurants, gravel pits, small ponds and the riverside (Chena) in Fairbanks, interior Alaska located app. 120 miles south of the arctic circle. We did 50 geo-referenced point surveys and detections in a rapid assessment fashion. Some opportunistic data were also taken when cruising. Gull data included presence/absenc. Data were geo-referenced with a GPS in decimal degrees (latitude and longitude, geographic datum of WGS84) collected in early breeding season, 12th of May in 2015 on a Tuesday (regular shopping and business times in the U.S.) between 7 AM and 7 PM by driving opportunistically on public strip mall parking lots, domestic areas and other locations of relevance for gull presences and absences in the survey area (app. 200m radius). Other species were also recorded but received less attention. These non-intrusive citizen science car-based surveys result into a virtually unbiased data providing a representative snap shot in space and time for the study area. Stripmall parking lots near rivers and (gravel) lakes represent a typical situation of where Common Gulls are found in an urban habitat during breeding season. We reported basic gull behaviour also. Some other bird species were recorded as well but not in great detail, e.g. American Wigeon, Pigeon, White-crowned Sparrow, Swallow sp, Shorebirds sp, Mallard, Lesser Yellowleg, American Robin, Common Raven, Grassland birds, Northern Shoveler, Grebe sp., and Dark-eyed Junco. Noteworthy are the very high raven and gull numbers at the city garbage dump. The gull abundance seems to be driven by food items on the parking lot, e.g. provided by an adjacent fast food restaurant and by wetland areas nearby (e.g. Chena river and gravel pits) where the gulls find good conditions for nearby nesting. Gulls seem to be quite colonial. This survey is unique and contributes to multi-year baseline information relevant for gulls, ravens, urban subsidized predators (e.g. raptors) in the interior of Alaska. They are a simple but powerful snapshots in time and space and when put into an overall ecological context, e.g. as done with Geographic Information System (GIS) analysis. Some photos exist for visual information. The dataset is provided in MS Excel, consists of 156 rows and is less than 1MB in size.
    • Opportunistic Survey Data of Mew Gull (Larus canus) and other detections in an Urban Environment, downtown Fairbanks, Interior Alaska in mid-June 2013

      Huettmann, Falk (EWHALE lab, University of Alaska-Fairbanks (UAF), 2013-07-31)
      This dataset presents a Mew Gull (Larus canus, Taxonomic Serial Number TSN 176832) survey data set for urban areas and stripmall parking lots (app. 300mx600m), super markets, fast food restaurants, gravel pits, small ponds and the riverside (Chena) in Fairbanks, interior Alaska located app. 120 miles south of the arctic circle. We did geo-referenced 80 point surveys and detections. Data were geo-referenced with a GPS in decimal degrees (latitude and longitude, geographic datum of WGS84) collected 22th of June in 2013 on a Saturday (regular shopping and business times in the U.S.) between 9.30 AM and 5 PM by driving opportunistically on public strip mall parking lots, domestic areas and other locations of relevance for gull presences and absences in the survey area (app. 200m radius). These non-intrusive citizen science car-based surveys result into a virtually unbiased data providing a representative snap shot in space and time. Stripmall parking lots near rivers represent a typical situation of where Mew Gulls are found in an urban habitat during breeding season. We reported basic gull behaviour also. Some other bird species were recorded as well, e.g. Golden Eagle (Aquila chrysaetos 175407), Northern Raven (Corvus corax 179725), Sandhill Crane (Grus canadensis 176177), Bald Eagle (Haliaeetus leucocephalus 175420), Gull sp. (Larus 176803), American Robin (Turdus migratorius 179759). The gull abundance seems to be driven by food items on the parking lot, e.g. provided by an adjacent fast food restaurant and by wetland areas nearby (e.g. Chena river and gravel pits) where the gulls find good conditions for nearby nesting. This survey is unique and contributes to baseline information relevant for gulls, ravens, urban subsidized predators (e.g. eagles) in the interior of Alaska. They are a simple but powerful snapshots in time and space and when put into an overall ecological context, e.g. as done with Geographic Information System (GIS) analysis. Some photos are provided for visual information. The dataset is provided in MS Excel and less than 1MB in size.
    • Optical Remote Sensing Of Snow On Sea Ice: Ground Measurements, Satellite Data Analysis, And Radiative Transfer Modeling

      Zhou, Xiaobing; Li, Shusun; Stamnes, Knut; Sharpton, Buck; Jeffries, Martin O.; Echelmeyer, Keith (2002)
      The successful launch of the Terra satellite on December 18, 1999 opened a new era of earth observation from space. This thesis is motivated by the need for validation and promotion of the use of snow and sea ice products derived from MODIS, one of the main sensors aboard the Terra and Aqua satellites. Three cruises were made in the Southern Ocean, in the Ross, Amundsen and Bellingshausen seas. Measurements of all-wave albedo, spectral albedo, BRDF, snow surface temperature, snow grain size, and snow stratification etc. were carried out on pack ice floes and landfast ice. In situ measurements were also carried out concurrently with MODIS. The effect of snow physical parameters on the radiative quantities such as all-wave albedo, spectral albedo and bidirectional reflectance are studied using statistical techniques and radiative transfer modeling, including single scattering and multiple scattering. The whole thesis consists of six major parts. The first part (chapter 1) is a review of the present research work on the optical remote sensing of snow. The second part (chapter 2) describes the instrumentation and data-collection of ground measurements of all-wave albedo, spectral albedo and bidirectional reflectance distribution function (BRDF) of snow and sea ice in the visible-near-infrared (VNIR) domain in Western Antarctica. The third part (chapter 3) contains a detailed multivariate correlation and regression analysis of the measured radiative quantities with snow physical parameters such as snow density, surface temperature, single and composite grain size and number density. The fourth part (chapter 4) describes the validation of MODIS satellite data acquired concurrently with the ground measurements. The radiances collected by the MODIS sensor are converted to ground snow surface reflectances by removing the atmospheric effect using a radiative transfer algorithm (6S). Ground measured reflectance is corrected for ice concentration at the subpixel level so that the in situ and space-borne measured reflectance data are comparable. The fifth part (chapter 5) investigates the single scattering properties (extinction optical depth, single albedo, and the phase function or asymmetry factor) of snow grains (single or composite), which were calculated using the geometrical optical method. A computer code, GOMsnow, is developed and is tested against benchmark results obtained from an exact Mie scattering code (MIE0) and a Monte Carlo code. The sixth part (chapter 6) describes radiative transfer modeling of spectral albedo using a multi-layer snow model with a multiple scattering algorithm (DISORT). The effect of snow stratification on the spectral albedo is explored. The vertical heterogeneity of the snow grain-size and snow mass density is investigated. It is found that optical remote sensing of snow physical parameters from satellite measurements should take the vertical variation of snow physical parameters into account. The albedo of near-infrared bands is more sensitive to the grain-size at the very top snow layer (<5cm), while the albedo of the visible bands is sensitive to the grain-size of a much thicker snow layer. Snow parameters (grain-size, for instance) retrieved with near-infrared channels only represent the very top snow layer (most probably 1--3 cm). Multi-band measurements from visible to near-infrared have the potential to retrieve the vertical profile of snow parameters up to a snow depth limited by the maximum penetration depth of blue light.
    • Optimizing landbird surveys for detecting population and spatial dynamics

      Mizel, Jeremy D.; Lindberg, Mark; Breed, Greg; Powell, Abby; Schmidt, Joshua (2017-12)
      Landbird populations are undergoing concurrent changes in population size, spatial distribution, and phenology. The sensitivity of landbird monitoring programs to detect and distinguish these varied processes is of critical importance. Consequently, these efforts require inference methods that are efficient and fully leverage information about spatial, population, and phenological dynamics. The development of efficient inference methods can be addressed in part through a thorough understanding of how the data are actually generated, the application of sampling methods that attempt to maximize encounter probability, and the tailoring of sampling methods to maximize sensitivity to specific inference objectives. Chapter one of this dissertation is concerned with accommodating temporary emigration in spatial distance sampling models. Model-based distance sampling is commonly used to understand spatial variation in the density of wildlife species. The standard approach is to assume that individuals are distributed uniformly in space and model spatial variation in abundance using plot-level effects. Thinned point process models for surveys of unmarked populations (spatial distance sampling) frame the sampling process in terms of the individual encounter in space and, consequently, are expected to offer greater sensitivity for understanding spatial processes. However, existing spatial distance sampling approaches are conditioned on the assumption that all individuals are present and available for sampling. Temporary emigration of individuals can therefore result in biased estimates of abundance. Herein, I extend spatial distance sampling models to accommodate temporary emigration. A simulation study indicated more precise and less biased estimation under the spatial distance sampling model compared to models that assume a uniform distribution of individuals and assess spatial variation in abundance using plot-level effects. An applied example involving two arctic-breeding passerines indicated considerably stronger inference under the spatial distance sampling model than standard distance sampling models. Chapter two is concerned with the capacity of subarctic passerines to adjust their arrival timing to relatively extreme variation in spring conditions. I assessed interannual variation in passerine arrival timing in Denali National Park, Alaska from 1995-2015, a period that included both the warmest and coldest recorded mean spring temperatures for the park. Neotropical-Nearctic migrants varied in terms of the flexibility of their arrival timing, but generally showed plastic phenologies, suggesting resilience under extreme spring conditions. In comparison, Nearctic-Nearctic migrants showed similar or greater plasticity in arrival timing. A majority of species showed synchronous-asynchronous fluctuation in arrival (i.e., synchronous arrival in some years, asynchronous in others) in combination with various levels of the mean response (i.e., early, average, and late arrival), suggesting the presence of interactions between environmental conditions at multiple scales and inter-individual variation. Overall, these findings suggest that monitoring of the mean-variance relationship may lead to a deeper understanding of the factors shaping phenological responses. Chapter three is concerned with developing efficient inference methods for inventorying and monitoring cliff-nesting raptor populations. In nest occupancy studies of cliff-nesting raptors, the standard approach is to allocate a level of survey effort that is assumed to ensure that the occupancy state is known with certainty. However, allocating effort in this manner is inefficient, particularly at landscape scales, constraining our capacity for effective management of these species. To increase survey efficiency and expand the spatial inference of these studies, I developed two versions of a multi-state, time-removal model, one for long-term monitoring studies and another for population inventories or single-season surveys in which there is no prior knowledge of nest locations. For long-term monitoring of species with alternative nests, I formulated a version of the model that accounts for state uncertainty at the territory-level caused by a failure to observe all nests within a territory. Simulation studies indicated generally low to moderate relative bias under the monitoring and inventory models. In addition, I applied the monitoring model to a long-term study of golden eagles (Aquila chrysaetos) in Alaska and demonstrate that the maximum effort spent on any nesting territory could be reduced by up to almost 90% of that recommended by standard protocols.
    • The origin and composition of aerosols in the Alaskan airshed

      Wilcox, Walter James (2001-12)
      Since the Alaskan airshed north of the Alaska Range receives a substantial portion of its anthropogenic aerosol and gaseous pollutants through long-range transport, Alaskan air quality is influenced to an unusually high degree by the political and economic events of other countries. An understanding of the political and economic forces at work in the various circumpolar nations is key to an understanding of the observed decline in Arctic haze, the present state of Arctic air pollution, and likely future developments. It is shown in this thesis that Arctic haze has declined in Interior Alaska over the last decade and a half. This decline appears to be driven by the widespread emission reductions which have occurred in North America, Europe, and the former Soviet Union (FSU) between 1988 and 1998. If true, this linkage indicates that the story of Arctic haze is not yet a post-mortem. EMEP projections for 2005 foresee a continuing decline in emissions across Europe and a leveling off in North America, but emissions in the European FSU are expected to double by 2005. Events in the FSU, and perhaps Asia as well, threaten to abrogate any further progress made by Europe and North America and could perhaps revive the phenomenon.
    • Origins And Zoning Of The Buckhorn Gold Skarn, Ne Washington

      Deal, Michelle L.; Newberry, Rainer (2012)
      The Buckhorn Deposit was discovered in the mid 1980's and is composed of two separate Au-Bi deposits: the Gold Bowl and the Southwest Zone. The Southwest Zone is the larger of the two and is blind and stratabound. The Gold Bowl is exposed on the surface. Jurassic and Eocene plutonic rocks are present in the immediate area, indicating a complex geologic history and two potential mineralization ages. To determine the source- and thus the age- of gold mineralization I use chemical analyses of (>300) igneous rocks, X-ray Fluorescence (XRF) determination of (>200) Bi/Au, Cu/Au, and Cu/Pb ratios throughout the ore zones, Fe:Mg ratios of skarn clinopyroxenes determined by EMP analyses, calc-silicate mineral zoning, surface and underground mapping, and Ar40/Ar39 dating of Au-intergrown skarn hornblende. Chemical classification of igneous rocks distinguishes seven potential source intrusions in the immediate Buckhorn area. Metal zoning (Bi/Au, Cu/Au, and Cu/Pb) throughout the entire deposit showcases the lack of relationship between the Gold Bowl and the Southwest Zone, allowing for multiple source and remobilization interpretations. However, the techniques employed all indicate an east to west ore fluid migration across the Southwest Zone and reveal a newly-unrecognized zoned Jurassic pluton SE and below the deposit as the source.