• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 638
  • 59
  • 50
  • 50
  • 50
  • 50
  • 50
  • 47
  • 46
  • 31
  • 30
  • 13
  • 10
  • 9
  • 8
  • Tagged with
  • 1067
  • 174
  • 148
  • 134
  • 118
  • 113
  • 103
  • 85
  • 71
  • 70
  • 67
  • 66
  • 59
  • 58
  • 58
  • 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.
241

Impacts of climate change and intensive lesser snow goose (Chen caerulescens caerulescens) activity in high Arctic pond complexes - Banks Island, Northwest Territories

Campbell, Thomas Kiyoshi Fujiwara 05 February 2019 (has links)
Rapid increases in air temperature in Arctic and subarctic regions are driving significant changes to surface water. These changes and their impacts are not well understood in sensitive high Arctic ecosystems. This thesis explores changes in surface water in the high Arctic pond complexes of western Banks Island, Northwest Territories, and examines the impacts of this change on vegetation communities. Landsat imagery (1985-2015) was used to detect trends in surface water, moisture, and vegetation productivity, aerial imagery change detection (1958 and 2014) quantified shifts in the size and distribution of waterbodies, and field sampling investigated factors contributing to observed changes. The impact of expanding lesser snow goose populations on observed changes in surface water was investigated using the aerial imagery change detection of 2409 waterbodies and an information theoretic model selection approach, while their impact on vegetation was assessed using data from field surveys. Our analyses show that the pond complexes of western Banks Island are drying, having lost 7.9% of the surface water that existed in 1985. This loss of surface water disproportionately occurred in smaller sized waterbodies, indicating that climate is the main driver. Model selection showed that intensive occupation of lesser snow geese was associated with more extensive drying and draining of waterbodies and suggests this intensive habitat use may reduce the resilience of pond complexes to climate warming. Evidence from field surveys suggests that snow goose foraging is also contributing to patches of declining vegetation productivity within drying wetland areas. Diminishing and degrading high Arctic pond complexes are likely to alter permafrost thaw and greenhouse gas emissions, as well as the habitat quality of these ecosystems. Additional studies focused the mechanisms of surface water loss, the direct impacts of wetland drying on vegetation, and the contributions of snow geese to these processes, are necessary to better understand the changes occurring on Banks Island. / Graduate
242

Inuit and scientific ways of knowing and seeing the Arctic landscape

Heyes, Scott Alexander. January 2002 (has links) (PDF)
"February 2002" Bibliography: leaves 117-128. This work explores traditional Inuit and Western scientific ways of knowing and seeing the Arctic through a number of cultural expressions of landscape. Inuit and Western perceptions of the Arctic are analysed by examining a series of thematic and cognitive 'maps', drawings and satellite imagery. The study focuses on how these forms of landscape representation and methods of navigation shape the way in whcih the Arctic is perceived. Centred on Inuit coastal villages in Nunavik (Northern Quebec), Canada, the study illustrates different and converging ways of reading the landscape through maps.
243

Canadian sovereignty over the Arctic Archipelago

McConnell, William Howard 14 September 2007
The central problem of the thesis is to investigate the international legal validity of the Canadian claim to the Arctic Archipelago. In order to consider the bearing on the problem of the "sector principl" the area investigated comprised the islands, waters and permanent ice lying between the the 60th and 141st meridians of west longitude extended to the North Pole, which meridians are northerly projections of Canada's easternmost and westernmost boundaries.<p> After a brief review of the facts and law surrounding the transfer of British Arctic possessions to Canada in 1870 and 1800, the international law applicable to archipelagic formations and to the acquisition of title to terrae nullius was examined. There followed, in the perspective of international law and the historical precedents, an examination of the Canadian claims to (a) the islands of the Arctic Archipelago, and (b) the adjacent waters, especially the aftermath of the two voyages of the Manhattan and the Canadian legislation of June, 1970, extending territorial waters to a breadth of twelve miles and creating a large anti-pollution zone.<p> It was concluded that Canada's claim to the islands was very strong, either under the "prescription" or the "consolidation" doctrines, especially in the absence of serious adverse claims, and in the light of a vigorous Canadian manifestation of animus occupandi for several decades, at least.<p> Although the validity of the recent Canadian Maritime claims had been questioned by the United States, it was suggested either on the basis of the "consolidation" doctrine or in view of the evolving, norms of the international law of the sea that here also Canada could make out a strong case in support of the legislation of June, 1970.
244

Analyzing pan-Arctic 1982–2006 trends in temperature and bioclimatological indicators (productivity, phenology and vegetation indices) using remote sensing, model and field data

Luus, Kristina 28 August 2009 (has links)
Warming induced changes in Arctic vegetation have to date been studied through observational and experimental field studies, leaving significant uncertainty about the representativeness of selected field sites as well as how these field scale findings scale up to the entire pan-Arctic. The purposes of this thesis were therefore to 1) analyze remotely-sensed/modeled temperature, Normalized Difference Vegeta- tion Indices (NDVI) and plant Net Primary Productivity (NPP) to assess coarse- scale changes (1982–2006) in vegetation; and 2) compare field, remote sensing and model outputs to estimate limitations, challenges and disagreements between data formats. The following data sources were used: • Advanced Very High Resolution Radiometer Polar Pathfinder Extended (APP- x, temperature & albedo) • Moderate Resolution Imaging Spectroradiometer (MODIS, Normalized Dif- ference Vegetation Index (NDVI) & Enhanced Vegetation Index (EVI) ) • Landsat Enhanced Thematic Mapper (Landsat ETM, NDVI) • Global Inventory Modeling and Mapping Studies (GIMMS, NDVI) • Global Productivity Efficiency Model (GloPEM, Net Primary Productivity (NPP)) Over the pan-Arctic (1982-2007), increases in temperature, total annual NPP and maximum annual NDVI were observed. Increases in NDVI and NPP were found to be closely related to increases in temperature according to non-parametric Sen’ slope and Mann Kendall tau tests. Variations in phenology were largely non- significant but related to increases in growing season temperature. Snow melt onset and spring onset correspond closely. MODIS, Landsat and GIMMS NDVI data sets agree well, and MODIS EVI and NDVI are very similar for spring and summer at Fosheim Peninsula. GloPEM NPP and field estimates of NPP are poorly correlated, whereas GIMMS NDVI and GloPEM NPP are well correlated, indicating a need for better calibration of model NPP to field data. In summary, increases in pan-Arctic biological productivity indicators were ob- served, and were found to be closely related to recent circumpolar warming. How- ever, these changes appear to be focused in regions from which recent field studies have found significant ecological changes (Alaska), and coarse resolution remote sensing estimates of ecological changes have been less marked in other regions. Dis- crepancies between results from model, field data and remote sensing, as well as central questions remaining about the impact of increases in productivity on soil- vegetation-atmosphere feedbacks, indicate a clear need for continued research into warming induced changes in pan-Arctic vegetation.
245

Analyzing pan-Arctic 1982–2006 trends in temperature and bioclimatological indicators (productivity, phenology and vegetation indices) using remote sensing, model and field data

Luus, Kristina 28 August 2009 (has links)
Warming induced changes in Arctic vegetation have to date been studied through observational and experimental field studies, leaving significant uncertainty about the representativeness of selected field sites as well as how these field scale findings scale up to the entire pan-Arctic. The purposes of this thesis were therefore to 1) analyze remotely-sensed/modeled temperature, Normalized Difference Vegeta- tion Indices (NDVI) and plant Net Primary Productivity (NPP) to assess coarse- scale changes (1982–2006) in vegetation; and 2) compare field, remote sensing and model outputs to estimate limitations, challenges and disagreements between data formats. The following data sources were used: • Advanced Very High Resolution Radiometer Polar Pathfinder Extended (APP- x, temperature & albedo) • Moderate Resolution Imaging Spectroradiometer (MODIS, Normalized Dif- ference Vegetation Index (NDVI) & Enhanced Vegetation Index (EVI) ) • Landsat Enhanced Thematic Mapper (Landsat ETM, NDVI) • Global Inventory Modeling and Mapping Studies (GIMMS, NDVI) • Global Productivity Efficiency Model (GloPEM, Net Primary Productivity (NPP)) Over the pan-Arctic (1982-2007), increases in temperature, total annual NPP and maximum annual NDVI were observed. Increases in NDVI and NPP were found to be closely related to increases in temperature according to non-parametric Sen’ slope and Mann Kendall tau tests. Variations in phenology were largely non- significant but related to increases in growing season temperature. Snow melt onset and spring onset correspond closely. MODIS, Landsat and GIMMS NDVI data sets agree well, and MODIS EVI and NDVI are very similar for spring and summer at Fosheim Peninsula. GloPEM NPP and field estimates of NPP are poorly correlated, whereas GIMMS NDVI and GloPEM NPP are well correlated, indicating a need for better calibration of model NPP to field data. In summary, increases in pan-Arctic biological productivity indicators were ob- served, and were found to be closely related to recent circumpolar warming. How- ever, these changes appear to be focused in regions from which recent field studies have found significant ecological changes (Alaska), and coarse resolution remote sensing estimates of ecological changes have been less marked in other regions. Dis- crepancies between results from model, field data and remote sensing, as well as central questions remaining about the impact of increases in productivity on soil- vegetation-atmosphere feedbacks, indicate a clear need for continued research into warming induced changes in pan-Arctic vegetation.
246

Canadian sovereignty over the Arctic Archipelago

McConnell, William Howard 14 September 2007 (has links)
The central problem of the thesis is to investigate the international legal validity of the Canadian claim to the Arctic Archipelago. In order to consider the bearing on the problem of the "sector principl" the area investigated comprised the islands, waters and permanent ice lying between the the 60th and 141st meridians of west longitude extended to the North Pole, which meridians are northerly projections of Canada's easternmost and westernmost boundaries.<p> After a brief review of the facts and law surrounding the transfer of British Arctic possessions to Canada in 1870 and 1800, the international law applicable to archipelagic formations and to the acquisition of title to terrae nullius was examined. There followed, in the perspective of international law and the historical precedents, an examination of the Canadian claims to (a) the islands of the Arctic Archipelago, and (b) the adjacent waters, especially the aftermath of the two voyages of the Manhattan and the Canadian legislation of June, 1970, extending territorial waters to a breadth of twelve miles and creating a large anti-pollution zone.<p> It was concluded that Canada's claim to the islands was very strong, either under the "prescription" or the "consolidation" doctrines, especially in the absence of serious adverse claims, and in the light of a vigorous Canadian manifestation of animus occupandi for several decades, at least.<p> Although the validity of the recent Canadian Maritime claims had been questioned by the United States, it was suggested either on the basis of the "consolidation" doctrine or in view of the evolving, norms of the international law of the sea that here also Canada could make out a strong case in support of the legislation of June, 1970.
247

Cold : its demands and suggestions : a study of the importance of environment in the development of Eskimo culture

Nusbaum, Deric January 1939 (has links)
No description available.
248

Dynamical and thermodynamical influences of the tropics and midlatitudes on arctic hydroclimate variability

Hegyi, Bradley Michael 21 September 2015 (has links)
The Arctic is an important component of the Earth’s climate system, and it is a region dynamically coupled to climate phenomena at lower latitudes, through both atmospheric and oceanic paths. The coupling has significant effects on the hydroclimate variability in the Arctic, including effects on sea ice and Arctic precipitation. In this dissertation, we explore the coupling of the lower latitudes and the Arctic hydroclimate through atmospheric mechanisms with dynamical and thermodynamical components, with a focus on the following examples of variability: i) the decadal variability of boreal winter Arctic precipitation, ii) the variability of the strength of the stratospheric polar vortex in boreal winter, and iii) the initial melt of Arctic sea ice in late boreal spring. The goal of the research is to understand what drives the Arctic hydroclimate variability in each of these examples through improved knowledge of the mechanisms linking them to the tropics and Northern Hemisphere midlatitudes. In the first part of the analysis, we explore the mechanisms responsible for the decadal variability of boreal winter Arctic precipitation. We find that the decadal variability of cool-season Arctic precipitation is at least partly connected to decadal modulation of tropical central Pacific sea surface temperatures related to the El Niño-Southern Oscillation (ENSO). The modulation can be described as the oscillation between periods favoring central and eastern Pacific warming events [CPW and EPW, respectively], which are two common types of ENSO variability. By analyzing a collection of CPW and EPW events in reanalysis data, we establish the following connecting mechanism. First, the increase of central Pacific SSTs drive a Rossby wave train that destructively interferes with the zonal wavenumber 1 component of the background extratropical planetary wave in the subpolar region. Next, as a result of this interference, the magnitude of the vertical Rossby wave propagation from the troposphere to the stratosphere decreases and the stratospheric polar vortex strengthens. Finally, the strengthening of the vortex translates into a tendency towards a positive Arctic Oscillation (AO) in the troposphere and a poleward shift of the Northern Hemisphere midlatitude storm tracks, increasing moisture transport from lower latitudes and increasing total Arctic precipitation. In a further investigation of a crucial component of the above mechanism, the initial response of the stratospheric polar vortex to the influence of CPW and EPW is investigated. A 20-member ensemble run of an idealized model experiment in the NCAR Whole Atmosphere Community Climate Model (WACCM) is conducted with prescribed CPW and EPW pattern SST anomalies. Both CPW and EPW events weaken the polar vortex in the ensemble mean. The weakening is mainly tied to changes in the eddy-driven mean meridional circulation, with some contribution from eddy momentum flux convergence. There is a significant spread between ensemble members with identical CPW and EPW forcing, where a few of the ensemble members exhibit a weak strengthening response. The initial conditions of the extratropical atmosphere and subsequent internal variability after the introduction of the CPW and EPW forcing help drive the spread in response between individual members. In the last part of the analysis, using MERRA reanalysis data, the means by which atmospheric eddies affect the trend and variability of the initial melt of Arctic sea ice are explored. We focus specifically on the effects of lower troposphere (i.e. 1000-500 mb average) meridional heat transport by atmospheric eddies, a dynamical component of the atmospheric eddy mechanism, and eddy-generated surface downwelling shortwave and longwave radiation anomalies, a thermodynamical component. Although in a climatological sense, atmospheric eddies in all major frequency bands transport heat poleward into the Arctic, we find that the lower-troposphere eddy meridional heat transport does not contribute to the trend of an earlier initial melt date. However, eddy heat transport still plays an important role in the initialization of individual episodes of initial melt with large areal coverage. In the investigation of two specific episodes, the meridional heat transport term that represents the interaction between the eddy wind and mean temperature fields (i.e. the product of the meridional eddy wind and the mean temperature fields) is most associated with the initial melt in both episodes. Additionally, melt in one of the episodes is also associated with surface downwelling longwave and shortwave radiation anomalies, a result of eddy-generated cloud cover anomalies. Therefore, in individual melt events, the combination of direct eddy meridional heat transport and surface longwave and eddy-driven shortwave radiation anomalies may significantly contribute to the initial melt of Arctic sea ice. This combination may be especially important in episodes where significant initial melt occurs over a large area and over a period of a few days.
249

A culture in transition : a case study of Eastern Arctic students' creative work

Shapiro, Jane A. (Jane Ann), 1953- January 1989 (has links)
No description available.
250

Zooplankton distribution in the Arctic Ocean with notes on life cycles

Harding, Gareth C. H. January 1966 (has links)
During the Norwegian North Polar Expedition of 1893-96, the historie voyage of the Fram ( Sars, G.O. 1900), the first zooplankton collections were taken from the Arctic Basin. In 1931 the Nautilus made collections north of Spitzbergen, being the first submarine to attempt polar research (Farran, 1936). [...]

Page generated in 0.0245 seconds