The investigation of the role of basin-scale forcing on the circulation of the Faroe-Shetland Channel (FSC) is important to further understanding of the inter-annual variability of the Atlantic water (AW) fluxes in this region. The FSC plays a key role in the transfer of warm and saline AW towards the Nordic Seas that is an integral part of the Atlantic Meridional Overturning Circulation which is projected to decline over the twenty-first century and might reduce the oceanic heat and salt transports towards the Arctic. So far little attention has been paid to the mechanisms driving the AW fluxes in the FSC, reliable estimates of AW temperature and salt transports time series are lacking. This study presents a new time series of the AW fluxes based on the combination of hydrography and altimetry data. The mechanisms involved in driving the variability of AW fluxes are considered based on observational data and the output from a high-resolution ocean model (VIKING20). The hydrographic observations from 1993 to 2015 show an increase in temperature and salinity of AW. However, there is no evidence of trends in AW volume, temperature or salt transports during the observed period. This analysis confirms that the amount of heat and salt transported through the FSC is dominated by the volume transport. Moreover, this study identifies a bias in the standard deviation of the geostrophic velocity at a depth associated with referencing the geostrophic calculations to the sea surface geostrophic velocity from satellite altimetry. This finding does not strongly influence the AW volume transports in the AW layer, however, it has important implications for estimates of the geostrophic volume transport at depth. This study shows that the Ekman driven up/downwelling and the differential Ekman pumping mechanisms driven by the local wind forcing may influence sea surface height (SSH) and the displacement of isopycnals in the channel, leading to AW volume transport variabilit However, due to the large associated error bars on the surface and subsurface parameters, there is no clear evidence that these mechanisms are significantly responsible for the AW volume transport variability in the FSC. Lagrangian trajectories show evidence of two pathways from the North Atlantic to the FSC that may explain AW variability in the FSC: one pathway involves the flow of warm and saline waters from the Rockall Trough that corresponds to high temperatures and low AW volume transport in the channel, and the other pathway involves the flow of relatively cooler and less saline waters from the Iceland Basin that is linked to low temperatures and stronger volume transport in the FSC. Moreover, we show that the first (second) pathway is associated with the negative (positive) phases of the North Atlantic Oscillation (NAO) and the ocean gyre contraction (expansion). The changes of the NAO index phases explain 26 % of the AW volume transport variance in the FSC. Another important mechanism that leads to stronger (weaker) AW volume transport is stronger (weaker) pressure gradient across the Greenland-Scotland Ridge, reflected by the SSH changes. This mechanism explains 29 % of AW volume transport variance in the FSC.

This thesis investigates the archaeological potential of masonry mortars throughout North Atlantic Europe, with a particular focus on the buildings and environments of medieval northern and western Scotland. The results of an extensive non-intrusive survey of medieval and later buildings are presented, within which nine multiphase sites were subject to more comprehensive building, environment and materials analysis. The survey suggests that, in general, different mortar-making techniques had well-defined sub-regional distributions which are not simply a correlate of environmental availability, but developed in different ways over time. Moreover, all of the more comprehensively studied buildings contain evidence of striking material contrasts from phases to phase which has great potential in standing building analysis. Material contrasts in masonry evidence between building phases, between neighbouring buildings, between specific buildings and the regional corpus, and between the regions themselves, are then considered as evidence of changing cultural, chronological and environmental context. The relationship between secular and ecclesiastical buildings across the region is a particular concern. Qualitative lab-based and on-site material interpretations made throughout the thesis are supported by a programme of comparative experimentation. This thesis includes the first comprehensive investigation of lime mortars made from marine shells, the first evidence of lime mortars made from coralline algae, results from the first programme of dating medieval buildings in Scotland through radiocarbon analysis of relict mortar fuel, and microstructural analysis of a large range of medieval mortars from Norway to the Isle of Man. Wider research considers the initial emergence of mortared masonry in North Atlantic Europe and the relationship between clay and lime mortars. Ultimately, by placing the upstanding buildings archaeology at the centre of the medieval and later landscape this thesis will demonstrate that masonry mortars have significant potential to inform our understanding of the cultural and environmental context of lordship construction in the North Atlantic, providing a new focus for further interdisciplinary discourse.

Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

In this thesis, the role of mid-latitude cyclones in air pollution transport in the Northern Hemisphere is quantified. The storm tracking model, TRACK, is used to study the mechanisms through which pollution, specifically ozone (O3) and carbon monoxide (CO), are vented from the boundary layer to the free troposphere and thus transported over large distances, as well as the introduction of O3 from the stratosphere into the troposphere. The relationship between mid-latitude cyclones and air pollution transport of O3 and CO is explored for the first time using the Monitoring Atmospheric Composition and Climate (MACC) reanalysis, a combined meteorology and composition reanalysis dataset. A comparison between springtime surface ozone measurements at rural background sites on the west coast of Europe and cyclone track frequency in the surrounding regions was used to first establish the correlation between cyclone location and surface air quality. The focus is on spring as it tends to be the season of maximum intercontinental transport of O3. The surface observations were compared to the MACC O3 values at the same locations and case studies of how cyclones can influence surface O3 measurements are described. When cyclones track north of 53°N, there is a significant probability that the surface O3 will be high (> the 75th percentile), due to the close proximity to stratospheric intrusions and the transport at low levels across the North Atlantic Ocean. The most intense spring cyclones (95th percentile) were selected for two regions, the North Atlantic and the North Pacific, for further investigation into the mechanisms which impact O3 and CO concentrations near cyclones. These intense cyclones ( 60 over each region) often tracked over the major emission sources of eastern North America and East Asia. The distributions of MACC O3 and CO within a "typical" intense cyclone are examined by compositing the cyclones together. The cyclone-centered composites were compared to background composites of "average conditions" created by sampling the reanalysis data of the previous year to the cyclone locations. Mid-latitude cyclones are found to redistribute concentrations of O3 and CO horizontally and vertically throughout the cyclone. This is clearly shown to occur through two main mechanisms: (1) vertical lifting of CO-rich and O3-poor air isentropically from near the surface to the mid- to upper-troposphere in the region of the warm conveyor belt; and (2) descent of O3-rich and CO-poor air isentropically in the vicinity of the dry intrusion, from the stratosphere toward the mid-troposphere. This work was expanded to identify the links between teleconnection patterns, mainly the North Atlantic Oscillation (NAO), that affect the major storm track pathways in the North Atlantic sector and the distribution of MACC O3 and CO throughout the troposphere and lower stratosphere. For this analysis, TRACK was used to calculate seasonal weighted-average O3 and CO distribution maps based on the monthly NAO index. During positive NAO phase, the persistence of low pressures over the North Atlantic coupled with the Azores High promotes transport across the North Atlantic throughout the troposphere. During negative NAO phase, blocking high pressure in the eastern North Atlantic are known to occur, which shifts transport pathways to a more southerly zonal flow. This work demonstrates the complex relationship between the horizontal and vertical distribution of pollution, including surface concentrations, and synoptic-scale systems.

No description available.

As global temperatures rise due to anthropogenic climate change, water resources, thus economies, are threatened. A geologically recent period of increased temperatures is the mid-Holocene and an investigation of its climate may allow for a better understanding of future precipitation and changes to regional water resources. The regions of interest are tropical Northern Central America and subtropical North America with Belize and Florida representing each climate zone. By reconstructing mid-Holocene climate in Florida and Belize, I hope to provide a better understanding of how increased temperatures and a reduced latitudinal temperature gradient impacts both precipitation patterns and variability. Today, drivers of changes in precipitation include climate systems such as the Atlantic Multidecadal Variability (AMV), North Atlantic Oscillation (NAO), and the Intertropical Convergence Zone (ITCZ). Therefore, it is imperative to determine their latitudinal influences during the mid-Holocene and consequently their potential impact on water resources in the near future. Speleothems from Chen Ha Cave, Vaca Plateau, Belize and Brown's Cave, West Central Florida, provided high-resolution (sub-annual to decadal) oxygen and carbon stable isotope data that allowed for a detailed investigation of mid-Holocene climate. The speleothems were sampled along the growth axis of a cross-section for oxygen and carbon isotopic analysis. 234U-230Th dating was used to create a chronology for each record and determine the time step between each isotope sample. Time series analysis with variations of Fourier transforms, including Lomb-Scargle, wavelet analysis, and multi-taper method, was used to extract periodicities for each oxygen isotope record. To determine which atmospheric-oceanic modes influenced mid-Holocene precipitation, the speleothem periodicities were compared to those of known periodicities of atmospheric-oceanic modes, such as the AMV and NAO. Finally, the Florida and Belize records were assessed for coherency using cross wavelet analysis. The Floridian speleothem recorded less precipitation compared to present levels due to a westward expansion and intensification of the North Atlantic Subtropical High (NASH) with a quasi-persistent but less influential AMV. Relative to today, the mid-Holocene in Belize was slightly wetter which I suggest is a result of a more northerly ITCZ and an intensification of the NASH that increased the strength of the Caribbean Lower Level Jet (CLLJ). The Seuss solar cycle was also significant in Belize, contributing 7.2% of the precipitation variability. Wavelet coherency assessment reveal very little connectivity between the Florida and Belize speleothem reconstructions, potentially due to the blocking influence of the ITCZ. Comparison to other records from the mid-Holocene supports the hypothesis of an intensified NASH and more northerly ITCZ. A future increase in precipitation in Belize may lead to increased soil erosion, the need for crop adaptation, and risk to the population of low lying areas, such as Belize City. In Florida, reduced precipitation may result in a decrease in agricultural output and threats to the state's freshwater supply.

Historians of the founding years of the North Atlantic Treaty Organization (NATO) acknowledge General Dwight D. Eisenhower’s role as the first Supreme Allied Commander Europe (SACEUR), yet they ignore the effect Eisenhower’s rhetoric had in the creation of a sense of unity among Western European nations. Rhetorical analysis of Eisenhower’s time as SACEUR offers scholars a unique look into the founding years of NATO and the beginning of European unification. Using Kenneth Burke’s theory of the four master tropes, I analyze how Eisenhower’s role in the development of NATO was important to the eventual development of a unified Europe.

Recent changes in climate have increased public attention and scientific evaluation of climate impacts on wild animals and plants. Variation in local weather and regional climate may affect breeding success in birds. Migratory species may be sensitive to these changes as breeding and wintering areas may experience different climate variations; some insectivorous species may be unable to alter timing of migration or laying dates and experience a mismatch between timing of nesting and peak insect availability for their nestlings. Therefore, I investigated the influence of local weather variables and regional climate on breeding performance of an insectivorous migrant songbird, the Tree Swallow (<i>Tachycineta bicolor</i>), and tried to examine effects of a mismatch between the timing of breeding and food availability.<p>I used a 14 year data set from St. Denis, Saskatchewan, Canada, 1991-2004, to evaluate correlations among local weather, wetland conditions, aerial insects and regional climate indices and their relationships with variation in clutch initiation date, clutch size, and fledging success. Swallows returned to the study site in late April each year. Annual variation in median clutch initiation date was best explained by mean minimum temperatures during 1-15 May. Larger clutches were laid in years with higher pond water levels (possibly an indication of increased insect availability) and when the Southern Oscillation Index (SOI) was positive (representing La Niña conditions). Fledging success was not influenced greatly by any explanatory variable; however, fledging success tended to increase in years with higher average temperatures. Individual variation in clutch initiation date was examined using path analysis. I found high correlations between initiation date and both local environmental variables and regional climate indices; earlier nesting was associated with warmer temperatures (increased local temperatures, more positive North Atlantic Oscillation Index (NAOI) values and more negative SOI values) and decreased moisture (more positive NAOI values). Two reduced data sets, including female age or insect abundance, were also examined. Clutches were initiated earlier by older females and during springs with higher abundance of aerial insects.<p>I applied two heating treatments to nest boxes used by pre-laying swallows and compared reproductive measures (timing of nesting, laying sequence, clutch size, egg weight and fledging success) of birds using heated boxes to those of females attending unheated control boxes. However, I was unable to directly examine the predictions of the mismatch hypothesis because nest box heating failed to advance laying dates. Furthermore, no increases in clutch size, egg weight and fledging success were detected between treatment and control nests. Although box heating increased nest temperatures an average of 6.1C (+ 0.8 SE) over controls, length of time females spent in heated boxes may have been too short to alleviate energetic constraints on egg production, or energy savings associated with box use were insufficient to supersede the influence of ambient environmental conditions that control food availability and energy expenditure of foraging swallows. My results demonstrated that local and regional climate variation strongly affected timing of nesting in swallows, likely via their effects on food supply.

Stable isotope values of ostracod calcite provide a record of variation in ¥ä18O(H2O) values and water temperature from the late glacial to mid-Holocene in Western Ireland. Lough Monreagh, located in County Clare, Western Ireland, contains marl sediment that includes pristine ostracod calcite whose ¥ä18O and ¥ä13C values were evaluated. These values were used relative to modern ecological requirements to derive a paleoenvironmental record for Lough Monreagh that includes water temperature, eutrophication, water depth, as well as terrestrial vegetation and weathering within the lake¡¯s watershed. ¥ä13C values of ostracod calcite presented herein suggest a significant increase in terrestrial vegetation beginning during the Aller©ªd (13,600 cal year B.P.) and extending through to the mid-Holocene (6,997 cal year B.P.). Marl and ostracod ¥ä18O values record variability in temperature and precipitation ¥ä18O(H2O) values that are in turn forced by variation in atmospheric and oceanic circulation. Water temperatures presented herein were calculated from ¥ä18O values of ostracod calcite and marl, constrained by temperature preference and tolerance ranges of ostracod species, yielding the highest resolution temperature record covering this period to date. Over 4,700 ostracods representing all three freshwater superfamilies were counted and identified to evaluate the trophic stage of the lake. The lake was characterized as a clear-, cold-water (~8¨¬C summer water temperature), low-nutrient environment during the Aller©ªd, then freezes abruptly during the Younger Dryas as evidenced by black clay deposits aged 12,800 to 11,300 cal yr B.P. Following the Younger Dryas, transitional warming and increasing terrestrial vegetation are evidenced by decreasing ¥ä13C values of ostracoda and faunal transition to phytophyllic species. Summer water temperatures warm to >16¨¬C, with ostracod species suggesting a shallow-water, fen- and macrophyte-rich environment with abundant plant life in and around the lake by ~8,000 cal yr B.P.