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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
461

a study of material: a stone house in the arctic circle

McKinley, Abigail Joanne 13 June 2011 (has links)
the work that follows is a study in material and the nature of its construction. i chose a site that was rich in tradition of building, but chose to not mimic tradition. the arctic circle of norway has a tradition of stone and wood construction. the remote qualities of the site lead me to choose a house, of local stone and wood. the extreme conditions of the environment posed the challenges in design and construction. i did not test the limits of the stone, but let the stone do what is natural to it. i chose not to force the stone to be anything other than itself, and working with these natural tendencies to make the decisions of construction. / Master of Architecture
462

How have the European Commission (EC) and Arctic EU Member States constructed Russia as a security threat through evolving Arctic discourse?

Seidel, Emilia Ballaux January 2024 (has links)
There are currently growing geopolitical tensions within the Arctic region. Furthermore, climate change is quickly providing easier access to the Arctic region and its natural resources, strategic positioning, and unclaimed territory. Simultaneously, the EC and EU Arctic states are pushing public discourse with an incorporated distaste for the growing geopolitical tensions and increasing interest by certain states. However, there is a lack of academic literature applying a poststructuralist approach to the construction of these security threats within this topic. Therefore, the thesis will incorporate several theoretical tools by prominent poststructuralists such as Michel Foucault and Jacques Derrida, including identity, deconstruction, and power/knowledge for the analysis.  Moreover, the chosen methodological approach for the analysis is a predicate analysis. The predicate analysis aided the thesis in successfully approaching the research question, by exploring how the EC and EU Arctic states have constructed Russia as a security threat through their public Arctic discourse. Thus, the findings concluded that the EC and EU Arctic states do construct Russia as a security threat within their public discourse through the chosen theoretical tools.
463

The Combined Role of ENSO-driven Sea Surface Temperature Variation and Arctic Sea Ice Extent in Defining Climate Conditions in the Southwestern United States

Chassot, Amanda M. 08 July 2009 (has links)
Previous research indicates that future reductions in Arctic sea ice cover (SIC) could alter storm tracks and precipitation patterns in western North America and negatively impact water resources in the American southwest. Other research suggests that multiple periods of increased precipitation and/or cooler temperatures in the American southwest during the Little Ice Age (LIA) were due to strong El Niño events; historical records also describe expanded Arctic SIC at this time. We use 16th-19th century Arctic SIC records from the ACSYS Historical Ice Chart Archive as a basis for expanding Arctic SIC from 1870 HadISST data to theoretical LIA extents. Then, in a suite of sensitivity studies, we investigate the relative influences of and interactions between El Niño-Southern Oscillation (ENSO) related sea surface temperature (SST) variation and varying Arctic SIC in controlling storm tracks, precipitation patterns, and overall climate conditions in the American southwest. We find that tropical Pacific SSTs greatly influence climate system response to variability in Arctic SIC, with ENSO-Neutral SSTs permitting the greatest response. Additionally, the degree of expansion and symmetry of Arctic SIC also influence precipitation regime response. These findings suggest that the climate response to future Arctic SIC retreat may not only be highly dependent on the spatial patterns and extent of SIC reductions, but also upon ENSO variability, such that El Nino events may reduce the potential climate impact of ice reductions as compared to Neutral or La Nina events. / Master of Science
464

Isotope-based source apportionment of black carbon aerosols in the Eurasian Arctic

Winiger, Patrik January 2016 (has links)
Aerosols change the Earth's energy balance. Black carbon (BC) aerosols are a product of incomplete combustion of fossil fuels and biomass burning and cause a net warming through aerosol radiation interactions (ari) and aerosol cloud interactions (aci). BC aerosols have potentially strong implications on the Arctic climate, yet the net global climate effect of BC is very uncertain. Best estimates assume a net warming effect, roughly half to that of CO2. However, the time scales during which CO2 emissions affect the global climate are on the order of hundreds of years, while BC is a short-lived climate pollutant (SLCP) with atmospheric life times of days to weeks. Climate models or atmospheric transport models struggle to emulate the seasonality and amplitude of BC concentrations in the Arctic, which are low in summer and high in winter/spring during the so called Arctic haze season. The high uncertainties regarding BC's climate impact are not only related to ari and aci, but also due to model parameterizations of BC lifetime and transport, and the highly uncertain estimates of global and regional BC emissions. Given the high uncertainties in technology-based emission inventories (EI), there is a need for an observation-based assessment of sources of BC in the atmosphere. We study short-term and long-term observations of elemental carbon (EC), the mass-based analog of optically-defined BC. EC aerosol concentrations and carbon-isotope-based (δ13C and ∆14C) sources were constrained (top-down) for three Arctic receptor sites in Abisko (northern Sweden), Tiksi (East Siberian Russia), and Zeppelin (on Svalbard, Norway). The radiocarbon (∆14C) signature allows to draw conclusion on the EC sources (fossil fuels vs. biomass burning) with high accuracy (&lt;5% variation). Stable carbon isotopic fingerprints (δ13C) give qualitative information of the consumed fuel type, i.e. coal, C3-plants (wood), liquid fossil fuels (diesel) or gas flaring (methane and non-methane hydrocarbons). These fingerprints can be used in conjunction with Bayesian statistics, to estimate quantitative source contributions of the sources. Finally, our observations were compared to predictions from a state of the art atmospheric transport model (coupled to BC emissions), conducted by our collaborators at NILU (Norwegian Institute for Air Research). Observed BC concentrations showed a high seasonality throughout the year, with elevated concentrations in the winter, at all sites. The highest concentrations were measured on Svalbard during a short campaign (Jan-Mar 2009) focusing on BC pollution events. Long-term observations showed that Svalbard (2013) had overall the lowest annual BC concentrations, followed by Abisko (2012) and Tiksi (2013). Isotope constraints on BC combustion sources exhibited a high seasonality and big amplitude all across the Eurasian Arctic. Uniform seasonal trends were observed in all three year-round studies, showing fractions of biomass burning of 60-70% in summer and 10-40% in winter. Europe was the major source region (&gt;80%) for BC emissions arriving at Abisko and the main sources were liquid fossil fuels and biomass burning (wood). The model agreed very well with the Abisko observations, showing good model skill and relatively well constrained sources in the European regions of the EI. However, for the Svalbard and East Siberian Arctic observatories the model-observation agreement was not as good. Here, Russia, Europe and China were the major contributors to the mostly liquid fossil and biomass burning BC emissions. This showed that the EI still needs to be improved, especially in regions where emissions are high but observations are scarce (low ratio of observations to emitted pollutant quantity). Strategies for BC mitigation in the (Eurasian) Arctic are probably most efficient, if fossil fuel (diesel) emissions are tackled during winter and spring periods, all across Eurasia. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript.</p>
465

Biogenic silica dynamics of Arctic marine ecosystems

Giesbrecht, Karina 05 April 2019 (has links)
Marine diatoms are the dominant primary producers in coastal and shelf regions, and contribute to about 20% of the annual photosynthesis on Earth. Diatoms also exert a major control on the marine silicon (Si) cycle through the formation of biogenic silica (bSiO2). Continental shelves account for half of the total marine area in the Arctic, yet our knowledge of the cycling of Si for this critically climate-impacted region is limited. The overall objective of this thesis was to improve our understanding of marine bSiO2 dynamics and Si cycling in marine Arctic and Subarctic ecosystems using novel techniques. Phytoplankton and nutrient observations, including dissolved and particulate silica concentrations, are presented from a period of ten years within five biological ‘hotspots’ in the Bering and Chukchi Seas. The first measurements of bSiO2 production and dissolution rates are also presented from a period of four years at the same sites. Results from this work show that (i) although interannual variability is high, diatoms are responsible for most of the high primary productivity in the Bering and Chukchi Seas, (ii) bSiO2 is primarily re-dissolved within the euphotic zone rather than exported, and (iii) phytoplankton phenology and marine Si cycling are affected by short-term climatic changes in this region. We also present the first measurements of bSiO2 production rates along a transect from the Canadian Arctic Archipelago (CAA), through Baffin Bay and into the Labrador Sea. We show that diatoms are both abundant and productive throughout these regions in summer, despite widespread Si limitation in the low-nutrient surface waters. Finally, we also investigated the natural variations in the Si isotopic composition of silicic acid (30Si(OH)4). On a transect through the Bering and Chukchi Seas, Canada Basin and CAA, and finally to Baffin Bay and the Labrador Sea, we found that δ30Si(OH)4 signals reflect water mass composition, the dissolution of bSiO2 throughout the water column, and the biological utilization of Si in surface waters. Ultimately, this work provides insight into the processes controlling marine Si cycling within the Arctic and its links to the global marine Si cycle and other biogeochemical cycles. / Graduate / 2020-03-13
466

Assessment of exposure and response to atmospherically-derived contaminants in U.S. Arctic freshwater fish

Allen-Gil, Susan M. 12 April 1995 (has links)
The Arctic has long been considered to be a pristine environment, far from population centers and pollution sources. The detection of synthetic organochlorine compounds in various elements of the Arctic food web has confirmed the global dispersion of pollutants, particularly of persistent compounds such as organochlorines and heavy metals. Levels of heavy metals, although elevated, appear to be naturally so throughout much of the Arctic. Arctic pollution is both a humanitarian and ecological concern. Many arctic coastal communities depend heavily on marine mammal fat for sustenance, and are therefore potentially exposed to high levels of organochlorines and some metals. From an ecological perspective, the structure of arctic food webs, the importance of lipid mobilization for winter survival, and the adaptive physiologies of arctic organisms may result in an enhanced response to contaminant exposure. This thesis assesses the exposure and effect of organochlorine and heavy metal exposure in inland freshwater ecosystems of Arctic Alaska, and evaluates the physiological response of arctic grayling to experimental polychlorinated biphenyl (PCB) exposure. / Graduation date: 1995
467

Water drag measurements on Arctic Sea ice

Shirasawa, Kunio. January 1975 (has links)
No description available.
468

An Examination of Sea Ice Spring and Summer Retreat in the Canadian Arctic Archipelago: 1989 to 2010

Tan, Wenxia 21 August 2013 (has links)
The sea ice extent change and variability of the Canadian Arctic Archipelago (CAA) are quite different compared to the Arctic as a whole due to its unique geographic settings. In this thesis, the sea ice retreat processes, the connection with other Arctic regions, and the linkages to the surface radiation flux in the CAA are examined. The sea ice retreat processes in the CAA follow a four-phase process: a slow ice melt phase that usually lasts until early June (phase 1); a quick melt phase with large daily sea ice extent change which lasts close to half-a-month (phase 2); a slow melt phase that looks like slow sea ice melt or even a small ice increase that lasts another half-a-month (phase 3); and a steady ice decrease phase (phase 4). With the help of Moderate-Resolution Imaging Spectroradiometer (MODIS) data, it is identified that the quick melt in phase 2 is actually melt ponding, with melt ponds being falsely identified as open water by passive microwave. A simplified data assimilation method is then developed to improve the passive microwave sea ice concentration estimation by fusion with MODIS ice surface temperature data. The ice concentration from the analysis is found to improve the original passive microwave sea ice concentration estimation, with the largest improvements during sea ice melt. The sea ice retreat patterns in the CAA region are correlated with the sea ice retreat patterns in other regions of the Arctic. A decision tree classifier is designed to segment the sea ice retreat patterns in the CAA into several classes and classification maps are generated. These maps are effective in identifying the geographic locations that have large changes in the sea ice retreat patterns through the years. The daily progressions of the surface radiation components are described in detail. Due to the lack of multiple reflection, the percentage of shortwave radiation at the top of atmosphere that reaches the surface is influenced by the form of melt ponds over ice surface. The roles that each surface radiation component plays in forcing sea ice retreat are different in different years.
469

Marine climatic change and its effects on commercial fisheries : northwest Atlantic and subarctic

Marr, Colin R. January 1984 (has links)
No description available.
470

Arktická strategie EU: Otázka aktérství Evropské unie / EU Arctic Strategy: Question of EU actorness

Slezáček, Filip January 2019 (has links)
This Master Thesis is depicting process of establishing actorness of the EU within international space, that is limited for this research on area of the Arctic. Policies of the EU are not uniformly developed, some are stronger, and some are weaker, that is a reason why in certain moments or position could be EU considered a non-actor. Document of Arctic Strategy is presenting system of three pillars- spheres in which the EU will be fulfilling its goals. Using the actorness assessment method by Bretherton, C. et Vogler, J. could be found out, how much a certain pillar is strong and whether the EU is able to fulfil its role as an actor in the light of its goals.

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