During the Arctic summer when the anthropogenic influence is limited, the natural marine source of sulfur in the form of gas-phase dimethyl sulfide viz. DMS(g), is of great importance for cloud formation. The harsh environment of the Arctic makes it difficult to perform in situ measurements of DMS(g) and hence regional model simulations can serve as a complement to increase our understanding of DMS related processes in the Arctic. In this thesis a regional scale meteorological forecast model, extended with DMS(g) calculations, is used to provide a consistent three-dimensional time evolving picture of DMS(g) over the pack-ice region. The analysis focus on meteorological aspects on the horizontal and vertical distribution of DMS(g). Our results show that the amount of DMS(g) over an oceanic source region alone does not determine concentration found over the pack-ice, the prevailing wind also exerts a large influence on the horizontal DMS(g) distribution. The modeled DMS(g) concentrations are advected in plumes in over the pack-ice, which, in combination with the photo-chemical decay, explain the large observed temporal variability of DMS(g) over the pack-ice. The modeled vertical structure show episodes with DMS(g) maxima well above the local boundary layer. Also shown is that DMS(g) maxima can be formed adjacent to frontal zones. In the presence of turbulence DMS(g) can be mixed downwards into the local boundary layer and aid growth to local particles and hence contribute to cloud formation in the boundary layer. / At the time of the doctoral defense the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 4: Manuscript.

Abstract The thesis includes two studies of Arctic charr, Salvelinus alpinus, responses to climate variation. In the first chapter, site-specific data from a fishery on the Hornaday River, Northwest Territories (NWT), are used to make inferences about the environmental drivers of observed variation in the mean biological characteristics of the catch. Mean length and weight characteristics of subsistence-fished Arctic charr available from 15 years of monitoring on the Hornaday River, were significantly influenced by among-year differences in local summer temperature and/or precipitation patterns. Environmental influences on mean length were age-specific, with temperature being the most important influence on younger (age-5) fish and precipitation being the most important influence on older (age-8) fish. Mean weight was positively influenced by precipitation only. Significant models of length-temperature relationships further indicated that larger mean sizes occurred in years when average summer air temperatures ranged from 6.7-7.1ºC. The effects of precipitation on nutrient exports to the nearshore marine area appear to trigger many of the observed correlations. Overall, results suggest that the large-scale environmental changes predicted by climate change scenarios will hold significant implications for Arctic charr from the Hornaday River, with population-specific effects likely to be exhibited in other northern Arctic charr populations. The second chapter uses archival biological data on 67 anadromous and lacustrine charr populations from eastern North America to assess variation within and among populations of Arctic charr as a function of latitude. Eastern North America was defined to include areas east of 80° W, including: Maine, the Canadian Maritime Provinces, insular Newfoundland, Labrador, Québec, and the eastern Arctic Islands of Baffin, Devon and Ellesmere. Obtained population data sets contained individual observations on age, length, weight, sex and fecundity of Arctic charr from as many age-classes as possible and included sufficient life-history information to permit grouping populations to life-history types: dwarf lacustrine, normal lacustrine and anadromous. Data were used to determine the significance of latitudinal clines in the biological responses as explanations of variation in age-specific biological characteristics (length and growth rate) among populations and life-history-types. The presence of a gradient in temperature and growing season length across latitudes was significantly related to a latitudinal compensation in the growth rate of all age-classes of normal and dwarf lacustrine Arctic charr populations. No decrease in dwarf length-at-age along the gradient was noted, whereas normal lacustrine length-at-age in the younger ages (age-4 to age-6) declined along the gradient. Results provide evidence of the applicability of the countergradient hypothesis as an explanation of among population differences in length-at-age for normal and dwarf lacustrine Arctic charr. Only weak evidence of the applicability of the countergradient hypothesis to anadromous Arctic charr populations was found. Although a decrease in length-at-age for all age-classes was observed along the gradient, only four age-classes (age-10 to age-13) showed a significant increase in growth rate with an increase in latitude. The similarity of the marine thermal environment across the latitudinal gradient is argued to account for the differential response of anadromous Arctic charr in comparison to lacustrine populations.

Abstract The thesis includes two studies of Arctic charr, Salvelinus alpinus, responses to climate variation. In the first chapter, site-specific data from a fishery on the Hornaday River, Northwest Territories (NWT), are used to make inferences about the environmental drivers of observed variation in the mean biological characteristics of the catch. Mean length and weight characteristics of subsistence-fished Arctic charr available from 15 years of monitoring on the Hornaday River, were significantly influenced by among-year differences in local summer temperature and/or precipitation patterns. Environmental influences on mean length were age-specific, with temperature being the most important influence on younger (age-5) fish and precipitation being the most important influence on older (age-8) fish. Mean weight was positively influenced by precipitation only. Significant models of length-temperature relationships further indicated that larger mean sizes occurred in years when average summer air temperatures ranged from 6.7-7.1ºC. The effects of precipitation on nutrient exports to the nearshore marine area appear to trigger many of the observed correlations. Overall, results suggest that the large-scale environmental changes predicted by climate change scenarios will hold significant implications for Arctic charr from the Hornaday River, with population-specific effects likely to be exhibited in other northern Arctic charr populations. The second chapter uses archival biological data on 67 anadromous and lacustrine charr populations from eastern North America to assess variation within and among populations of Arctic charr as a function of latitude. Eastern North America was defined to include areas east of 80° W, including: Maine, the Canadian Maritime Provinces, insular Newfoundland, Labrador, Québec, and the eastern Arctic Islands of Baffin, Devon and Ellesmere. Obtained population data sets contained individual observations on age, length, weight, sex and fecundity of Arctic charr from as many age-classes as possible and included sufficient life-history information to permit grouping populations to life-history types: dwarf lacustrine, normal lacustrine and anadromous. Data were used to determine the significance of latitudinal clines in the biological responses as explanations of variation in age-specific biological characteristics (length and growth rate) among populations and life-history-types. The presence of a gradient in temperature and growing season length across latitudes was significantly related to a latitudinal compensation in the growth rate of all age-classes of normal and dwarf lacustrine Arctic charr populations. No decrease in dwarf length-at-age along the gradient was noted, whereas normal lacustrine length-at-age in the younger ages (age-4 to age-6) declined along the gradient. Results provide evidence of the applicability of the countergradient hypothesis as an explanation of among population differences in length-at-age for normal and dwarf lacustrine Arctic charr. Only weak evidence of the applicability of the countergradient hypothesis to anadromous Arctic charr populations was found. Although a decrease in length-at-age for all age-classes was observed along the gradient, only four age-classes (age-10 to age-13) showed a significant increase in growth rate with an increase in latitude. The similarity of the marine thermal environment across the latitudinal gradient is argued to account for the differential response of anadromous Arctic charr in comparison to lacustrine populations.

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2003. / Thesis advisor(s): Wieslaw Maslowski, Stephen Okkonen. Includes bibliographical references (p. 103-107). Also available online.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains vi, 78 p. : ill. Vita. Includes abstract. Includes bibliographical references.

Submarine topographic features of the channels, sounds, fiords, and bays can best be explained as the products of extensive glacial excavation of a pre-existing drainage system. Troughs, hanging troughs, strings of deeps or basins, terminal sills, linear rises and depressions, and oversteepened deltas are considered direct or indirect evidence of glacial scour. Following glaciation, a negative movement of the Sverdrup Basin was accompanied by flooding of the northern part of the Archipelago. Only the upper portions of former interfluvial areas remained above sea level. These topographic highs are the present-day islands of the Canadian Arctic Archipelago. Statistical analyses of beach, fluvial, deltaic, and offshore marine sediments reveal characteristics that may be unique to polar deserts and ice-covered seas. Textures of beach and fluvial sediments are a function of associated relief and parent material. The deltaic environment is defined as that portion of the sea floor extending from the mouth of a river to approximately 3,200 feet from shore. Deltaic sediments show a progressive decrease in grain size seaward. Size distribution is related to the settling velocities of particles of different diameters. Offshore sediments have uniform textural properties. They are a combination of silt and clay (settled from suspension), and a minor but significant portion of sand- to granule-sized sediment (ice-rafted). An increase in mean grain size on the crests of submarine topographic highs suggests that winnowing by currents is taking place over these features. Two large areas of the sea floor lack a cover of Recent sediment. Organic carbon constitutes 0.84 to 2.14% of the offshore sediments. A dual source, terrigenous and phytoplanktonic, may explain the relatively high percentage of organic carbon. There is a positive correlation between percent organic carbon and amount of clay in the samples. Results of semiquantitative clay-mineral analyses of source rock, fluvial, deltaic, and offshore marine sediments indicate that montmorillonite, kaolinite, and illite are the dominant clay minerals. In this northern region, there is no change in clay mineralogy during weathering and transport. It is suggested that this may be characteristic of weathering under polar desert conditions. The mineralogy of parent materials on the islands controls the clay mineral distribution in offshore areas. In Louise Fiord, well-crystallized kaolinite is differentially flocculated close to shore. A study of the roundness of quartz grains of sand, silt, and clay size reveals that the distribution of this property is bimodal. Coarse and medium sands are well rounded, fine sands through coarse silts are angular, and fine silt and clay-sized particles are well rounded. High roundness of grains in the medium to coarse sand grades is attributed to abrasion. Well rounded quartz in the silt-clay size range is considered to be a product of solution. / text

The recently commissioned CANDAC Rayleigh?Mie?Raman Lidar (CRL) in Eureka, Nunavut, finished its first winter measurement campaign in 2010, during which over 900 hours of data was collected. A comparison of several inversion techniques are shown to de- termine which one is most appropriate for the CRL aerosol and cloud analyses. Results of a newly implemented automatic beam steering program are shown and discussed. Measure- ments of water vapour and aerosols showed a distinct layering effect in the troposphere. Back trajectories of these layers are compared to the CRL measurements to determine origins of these layers. Measurements of significant aerosol concentrations in the lower stratosphere were seen during the campaign, which were from the Sarychev eruption in June of 2009. The aerosol evolution over Eureka is shown by using different ground-based and satellite-based instruments. Calculations using multi-wavelength aerosol and cloud measurements are used to give insight on aerosol and cloud particle properties.

The response of vegetation to climate change and permafrost disturbance was studied at the Cape Bounty Arctic Watershed Observatory (CBAWO) on Melville Island, Nunavut. Climate change is expected to alter the terrestrial ecosystem of this area and cause non-linear responses. This study focussed on two predicted outcomes of climate change in the western Canadian High Arctic: the occurrence of a permafrost disturbance termed active layer detachments (ALDs), and increased air temperature and precipitation. To study the effects of ALD formation twenty 1 m2 plots were established within two ALDs. One ALD (ALD05) was formed in July 2007 and represented the initial impact of slope failure caused by an exceptionally warm year. The other (ALD04) was formed at least sixty years ago and represented the long-term impact of slope failure. Physical soil measurements and vegetation surveys were completed in both disturbances. ALD formation creates depressions on the landscape that increase snow accumulation. Snow accumulation was greater in the more recent ALD than in the older one and this resulted in greater changes to the physical environment. Vegetation was not significantly impacted by disturbance, although phenology was delayed due to snowcover retention. To study the effects of increased air temperature and precipitation an International Tundra Experiment (ITEX) site was established at CBAWO in July 2008. Snow fences and open-top chambers (OTC) were erected to increase snow accumulation and air temperature. Physical soil measurements and vegetation surveys were completed through the summer of 2009. Soil temperature and active layer depth were affected by snow and phenology was delayed in plots with snow enhancement. Experimental warming also had some effects on the parameters measured but only in conjunction with snow enhancement. This study found that in the first year of experimentation snow enhancement has a greater effect than increased air temperature. These studies represent the beginning of two long-term projects at CBAWO and the results from this study represent baseline data for future research. Continued monitoring will show the evolution of vegetation in the ALDs and the potential long-term effects of temperature and snow manipulation. / Thesis (Master, Geography) -- Queen's University, 2011-01-04 20:53:31.689

No description available.

This study represents the first of its kind to examine an extensive lithic debitage assemblage from a Late Dorset inland occupation. The assemblage derives from an isolated Late Dorset component at the LdFa-1 site, located along the northwest shore of Mingo Lake in the deep interior of southern Baffin Island. A study sample of 7,479 lithic debitage is systematically drawn and analyzed using two methodological approaches: individual attribute analysis and mass analysis. Patterns of variability derived from the analysis are isolated and interpreted within a technological organizational framework to identify Late Dorset lithic reduction and use strategies at the site. Using a multi-scalar approach, these results are then compared to those obtained from two inland Pre-Dorset sites, known as Sandy Point (LlDv-10) and Mosquito Ridge (MaDv-11) to draw some conclusions about how Palaeo-Eskimo populations more broadly organized their lithic technologies and used this terrestrial landscape over time.