Thesis (B.A.)--Haverford College, Dept. of Political Science, 2009. / Includes bibliographical references.

The concept of reciprocal acoustical travel-time measurements as a means of determining path-averaged currents is well established. We have designed an instrument to exploit this principle in studies of the boundary layer just beneath the arctic ice cover. Such measurements are of interest both because of the opportunity provided for comparison with the more commonly acquired point measurements and because of a particular configuration allowing determination of average vorticity, which cannot be achieved with the traditional approach; in addition, their unprecedented sensitivity allows detection of phenomena not observable with traditional sensors. The acoustical instrument was deployed during the spring of 1989 in the sub-ice boundary layer of the Eastern Arctic in order to measure turbulence, path-averaged horizontal current, and relative vorticity. A triangular acoustic array of side 200 m was used to obtain reciprocal transmission measurements at 132 kHz, at 8, 10 and 20 m beneath an ice floe. Pseudo-random coding and real-time signal processing provided precise acoustic travel time and amplitude for each reciprocal path. Mean current along each acoustic path is proportional to travel time difference between reciprocal transmissions. Horizontal velocity normal to the acoustic paths is measured using scintillation drift. The instrument measures horizontal circulation and average vorticity relative to the ice, at length scales characteristic of high frequency internal waves in the region. The rms noise level of the measurements is less than 0.1 mm/s for velocity measurements and 0.01 for vorticity, averaged over one minute. Except near the mechanical resonance frequency of the moorings, the measurement accuracy is limited by multipath interference. Path-averaged horizontal velocity is compared to point measurements and marked differences are observed due to local anomalies of the flow field. The integral measurement of current is particularly sensitive to the passage of internal waves that have wavelengths longer than the horizontal separation of the transducers. A comparison of horizontal velocity at two depths in the boundary layer shows good coherence at internal wave frequencies and some attenuation as the ice is approached. Relative vorticity at internal wave length scales is dominated by horizontal shear caused by flow interaction with ice topography and not by planetary vorticity. Reciprocal acoustical travel time measurements over paths of several hundred meters can be used to probe the statistical behaviour of turbulent velocity fine structure in the ocean. For homogenous isotropic flows, and for long measuring baselines, an analytic expression relating line-averaged and point measurements of velocity is derived. Anisotropic and inhomogeneous flows are also considered. Correction formulas for the spatial and temporal variability of advection velocity along the measuring baseline are obtained. Practical limitations are established, and experimental data from the arctic boundary layer beneath ice is compared with the theory. A new remote sensing technique for measuring turbulent kinetic energy dissipation rate is suggested. / Graduate

Prior to 1963 no previous vegetation studies had been undertaken in this region of the Low Arctic Subalpine/Foothill Zone of the Canadian Western Arctic, although several studies had been completed in similar regions in Arctic Alaska. This study was initiated in 1965 to obtain quantitative and qualitative data on vegetation and environmental relationships, including soil data for characterization of Low Arctic Subalpine/Foothill Zone soils. With these basic data it was considered possible to analyze, integrate and interpret community and soil relationships and to propose a usable classification system for the recognizable ecosystematic units in this portion of the zone. Initial criteria for selecting communities were based on uniformity and discreteness. Vegetation in each community was studied by the single plot method employing phytosociological techniques of the Zurich - Montpellier School as modified by Krajina (1933). Data on environmental conditions collected for each of 166 communities included degree of slope, profile, pattern of topography, exposure, altitude and wind influence. Coefficients of similarity between communities were computed using the formula 2W/A+B X 100, where A is the sum of all measures (abundance and presence) for one community, B is the sum of all measures for another community, and W is the sum of the lower values for each species which the two communities have in common. To determine the degree of affinity and relative hiatus points between groups of communities cluster analysis using the weighted pair - group method was employed. A two-dimensional dendrogram illustrated the individual plots and succeeding clusters. One soil pit was dug in every analyzed plot to either permafrost, water table, coarse ice shattered parent material or bedrock. A total of 498 soil samples for laboratory analysis were collected from all recognizable horizons. Chemical analyses were undertaken to determine organic matter content, total nitrogen, carbon/nitrogen ratio, absorbed phosphorus, exchangeable calcium, magnesium, potassium and sodium, cation exchange capacity pH. Because soil profiles showed considerable variation the results of the chemical analyses were averaged for the organic, organic - mineral and mineral horizons. On the basis of similarity of species composition six orders, eight alliances, fourteen associations, ten subassociations and thirteen variations were distinguished. The order Betuletalia glandulosae dominated the two study areas, occurring on moderately to well drained mesic to xeric slopes. Community development within this order appeared stable under the present topographic and climatic conditions. The Vaccinio - Betuletum glandulosae closely approximated the climatic climax in mesic habitats. Successional concepts on upper slopes appeared of limited value because communities tended to be discrete. Communities dominant on the lower slopes and in the wetlands were characterized by a narrow active, poor to impeded drainage conditions and more intensive frost action. Classification was more difficult in such areas because communities appeared to be less stable. Successional development in such areas with permanent seepage was toward the Betulo - Eriphoretum vaginati. Snow bed habitats were characterized by the order Petasitetalia frigidii , which was distinguished for the first time in North America, and included the previously undescribed Salicetum chamissonis. Sharp environmental gradients between chionophilous and chionophobous communities suggested that the climate had undergone no significant change in the recent past. Similarities between the Low Arctic Subalpine/Foothill Zone communities and those in other arctic regions, especially Scandinavia, were shown to occur. Twelve soil types were distinguished. In all but two cases each soil type was associated with a particular plant association. A form of podzolization previously described in Arctic Alaska was recognized in the Arctic Brown soils. Gleization, however, appeared to be the major soil forming process in this region of the zone. It was associated with both chionophobous and chionophilous vegetation. In the former, it was favoured by poor drainage, a shallow active layer and intensive frost action; in the latter, it appeared related to materials deposited on the snow that were later incorporated into the soil following snow melt. The high organic content and cation exchange capacity and the low acidity and base saturation were concluded to be important chemical characteristics of these soils. Final results using classification methods showed that the present position of the communities in this region of the Low Arctic Subalpine/Foothill Zone were related to elevation, exposure, soil moisture, thickness of the active layer, duration of snow cover, congeliturbation and topography. / Science, Faculty of / Botany, Department of / Graduate

This is a study of human response to the Arctic and Antarctic environments. It is based on two sources of data: the content analysis of original diaries of polar explorers, and the behavioural evaluation of contemporary crews in polar locations. In the latter, four polar stations were chosen, two in each polar region with a total of fifty-five experimental subjects. Twenty-seven other subjects acted as controls for both polar regions: a northern control group located at a semi-isolated site in Canada, and the southern group located in an Argentinian city. Methods applied in this research included the design and coding of categories which were content analyzed from the original diaries of explorers, and on-site procedures. On-site procedures included psychometric material, participant-observation reports and unstructured interviews. Fifteen behavioural measures within the domain of personality, perception of the environment, affection, social stress and community behaviour were administered. It was hypothesized that the human response would be similar in both polar regions because of environmental and sociological similarities, and that the polar setting would affect men and women in a negative way. Results showed that: (i) the polar environment is not perceived as stressful by the crews - a low anxiety state across both polar regions was found, (ii) traumatic experiences of the explorers had led to the perception of the environment in a negative perspective - yet the winter seemed to be a relaxing phase for the crews rather than stressful, (iii) personnel stationed at polar sites may possess special characteristics which distinguish them from the majority of the population, (iv) although cross-cultural differences exist, they are not as strong as might be anticipated - the environment exerts a unifying influence, (v) differences in gender-response are difficult to assess due to the small number of women subjects, but some differences with controls were noted. / Graduate and Postdoctoral Studies / Graduate

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"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.

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