Thesis (Ph. D.)--University of Washington, 1994. / Vita. Includes bibliographical references (leaves [135]-144).

Estuaries, the regions where runoff of fresh water, soil, and contaminants first encounter the ocean, are also primary fishing and recreation areas. It is therefore important to understand the dynamics associated with mixing and currents within these bodies of water. Pollutants and fresh water from river runoff flow out to sea in the upper layer, while nutrient-carrying oceanic water returns beneath. While there have been many studies of the processes involved in this exchange flow, the dynamics and vertical structure of transverse flows are much less understood, despite the role these currents play in redistributing water properties and momentum throughout the estuary. One such estuary, Juan de Fuca Strait, is an ideal location in which to study estuarine exchange and the resulting cross-channel flows induced by internal friction, primarily because its length and smooth topography reduce the topograpic steering of currents. Historical current meter data from a number of deployments in Juan de Fuca Strait reveal that, while mean along-channel currents are roughly consistent with the thermal wind equation, cross-channel flows are not, particularly at mid-depths where transverse currents are largest. A momentum balance using historical sea level and current meter data suggests that the vertical eddy viscosity Aᵥ ≈ 0.02 m²s⁻¹ at interfacial depths in May. The mean circulation in Juan de Fuca Strait-depths is highly seasonal in nature, however, and larger values may be more appropriate in summer when the estuarine exchange peaks due to the freshet. Stronger friction is in turn associated with elevated mixing rates and increased transverse velocities. An Acoustic Doppler Current Profiler deployed in Juan de Fuca Strait in the summer of 1996 resolved the vertical structure of these velocities. Concurrent Current-Temperature-Depth data reveal that neither the along- nor the cross-channel currents are in geostrophic balance with the hydrographic structure, suggesting that the physical processes associatd with these currents are more localised than the five kilometre scales over which the hydrography was measured. Zooplankton within Juan de Fuca Strait comprise a significant part of the scattering cross-section upon which the ADCP depends. During their dusk migration into the euphotic zone to feed and dawn descent to escape predation, they do not act as passive backscatter targets for the Acoustic Doppler Current Profiler. Vertical migration velocities, measured from the backscatter intensity record, reached 0.03 m s⁻¹, suggesting that significant biases in the measured vertical velocity could be introduced. Little effect was actually seen in the velocity fields, however, even though the cross-sectional fraction of the zooplankton was an order of magnitude larger than the background. Mean currents in Juan du Fuca Strait reveal strong transverse flows at mid-depths, suggestive of interfacial Ekman layers. The along-channel estuarine exchange is significantly enhanced at neap tide, consistent with weaker mixing upstream. The cross-channel flows at interfacial depths are also substantially larger during neap tide, implying a fortnightly modulation of mixing rates within the strait. The ADCP was also used to measure the Reynolds stresses directly. These were found to be more than an order of magnitude larger at neap tide than during spring tide and were consistent with changes in the mean current over the spring-neap cycle. Reynolds stresses were maximal at mid-depth on the transition from ebb to flood, at which time the gradient Richardson numbers were smallest, suggesting that critical layer absorption of internal waves are important dynamically. / Graduate

No description available.

No description available.

Preliminary results of a two-layer quasi-geostrophic box model of a wind-driven ocean are presented. The new aspects of this work in relation with conventional eddy models are a finite element formulation of the quasi-geostrophic equations and the use of no-slip boundary condition on the horizontal solid boundaries. In contrast to eddy resolving models that utilize free-slip boundary conditions our results suggest that the obtention of ocean eddies with the no-slip constraints requires a more restricted range of parameters, in particular much lower horizontal eddy viscosity eddy coefficients AH and higher Froude numbers F₁ and F₂. We show explicitly that a given range of parameters, which is eddy generating when the free-slip boundary condition is used, leads to a quasi-laminar flow in both, upper and lower, layers. An analytical model to interpret the numerical results is put forth. It is an extension of an earlier model of Ierley and Young (1983) in that the relative vorticity terms are of primary importance for the dynamics. Thus, it is shown that the boundary layer dynamics is active in the interior of the second layer, and it can be concluded from our method that for given F₁ and F₂ such that the lower layer geostrophic contours are closed, to the existence of the western boundary layer will prevent the homogenization of the potential vorticity so long as AH is large enough to stabilize the northwestern undulations of the flow. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Blocking is generally understood as the obstruction on a large scale of the normal west - to - east motion of mid-latitude pressure systems. It is a persistent phenomenon lasting from one to several weeks and the resulting prolonged weather regimes may have serious economic and social consequences. The recent Northern Hemisphere winters, starting with 1976-77, featured unusually large circulation anomalies, many of which can be directly related to prolonged episodes of large scale blocking. The intent of this study is to investigate the statistics and certain diagnostics of blocking in the Northern Hemisphere. The first of the three primary objectives is to present and interpret the spatial and temporal distribution of blocking during the past 33 years. We develop objective identification criteria, adaptable to machine processing methods, by relating the blocking anticyclone to its associated positive anomaly of 5-day mean 500MB height. Anomalies meeting the criteria are called 'blocking signatures.’ We present the seasonal frequency of occurrence of these signatures by longitude and by area. The results are in good agreement with published studies for the oceans, but they also reveal a high frequency of blocking signatures over the Northeastern Canadian Archipelago. This result, dubbed the 'Baffin Island Paradox' is further investigated and rationalized. A catalogue has been prepared which identifies the date, centre location and magnitude of every blocking signature which occurred from January 1, 1946 to December 31, 1978. A supplementary Catalogue identifies sequences of these signatures corresponding to actual blocking episodes The second objective is to investigate whether regions with high incidence of blocking, in either the developing or the mature stage, feature non-Gaussian distributions of 5-day mean geopotential. During winter, fields of significantly low kurtosis are found in certain mid-latitude regions where the genesis and amplification of blocking ridges are-frequently observed. Fields of significantly positive skewness are found in higher latitude regions where mature blocking episodes often interrupt the smaller fluctuations about the normal geopotential height. The final objective is to examine the association between the first six harmonics of the long wave pattern and the temporal and spatial characteristics of concurrent blocking episodes. Harmonics are calculated from profiles of daily 500MB height around latitude zones centred at 40°N and 60°N. Results for the northern zone are emphasized. It is found that there are spectral signatures distinctive to the regions where blocking anticyclones occur. Our results for the oceans are in general agreement with those of Austin (1980). During the strongly amplified meridional flow patterns associated with major blocking, we found that, at 60°N, more than 90% of the spatial variance of 500MB height is accounted for by wave components one to four. When the meridional regime gives way to predominantly zonal flow there is a marked reduction of spatial variance of 500MB height. During such regimes the higher harmonics (waves five and six) often make significant contributions (15 to 25%) to the total variance. The 'Baffin Island Paradox' is also studied using harmonics. It is found that in the majority of cases Baffin blocks originate from retrograding North Atlantic blocks. Finally, full latitude zonal harmonic analyses (15°N to pole, waves 1 to 4) are presented for three case studies of major blocking - (a) Greenland-North Atlantic, (b) Pacific Ocean-Alaska, and (c) Double Blocking. The harmonics often reveal two wave structures, one in the higher and other in the lower latitudes. The motion and growth characteristics of the two structures can be interpreted in terms of well-known features of total blocking systems. / Arts, Faculty of / Geography, Department of / Graduate

M.B.A. / Newspapers traditionally have had little trouble in producing profits. This is no longer the case and aspects such as the number of newspapers competing with each other for marketplace, have definitely brought in a sense of business to the world of communication. Coupled with ever increasing and very strong competition from both broadcast and new internet media for the same advertising slice, newspapers are slowly realizing that the media-marketplace is very different in the 21s t century. In a changing world, newspapers have to adapt or die. The challenge newspapers of 2002 and beyond face, is to appeal to even more readers and advertisers, to segment those readers better than ever before, to control costs while still investing in new technologies and to compete better with television yet retain the essential characteristics of newspapers. Change in the newspaper business is inevitable and in order to survive, newspapers will have to look more and more towards sound Media Management Principles, including Strategic Media Management, in order to turn newspapers into businesses and ensure survival

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

This Master’s thesis documents and interrogates networks of regional interaction in southwest Asia and Anatolia during the Neolithic and Chalcolithic periods (12,000 - 5700 B.P.) by comparing the variable use of obsidian raw material variants at 151 sites. This represents an effort to bring together all of the obsidian sourcing data produced for this broad archaeological setting, and evaluate it from a heterarchical approach that highlights the distributed nature of regional interaction. Heterarchical perspectives are applied here through the use of network analysis in order to highlight clusters of sites that are more connected to each other than they are to others in the system, and to determine the roles of each site in the system’s overall structure. As such, order is highlighted as a result of the organization of data-driven ties among sites, which are unrestricted by presumptions relating to geographical position or of pre-defined rank. The results are compared with more established models of regional interaction in the settings of interest, and heterarchical perspectives through network analysis are shown to complement common understandings of broad-scale connectivity at various points in time. / Thesis / Master of Arts (MA)

A thermal hydraulic analysis has been conducted to investigate the conditions leading to the channel flow reversal and the subsequent effects that may have on the Primary Heat Transfer System(PHTS) thermohydraulic parameters during the natural circulation under the specific accident scenarios for a generic CANDU 900 MW plant model similar to Darlington NGS. The assumed initiating events are the combination of a small Loss Of Coolant Accident (LOCA) with a loss of Class IV power, as well as the unavailability of Emergency Coolant Injection (ECI) system. No makeup inventory is taken into account in this study, and there is no fuel sheath temperature excursion or fuel centerline melting, i.e., the integrity of fuel is always maintained. A one-dimensional quasi-steady state Homogeneous Equilibrium Model(HEM) has been constructed for the study. A specific node-link structure is adopted to represent the primary heat transfer loop: The whole loop and different components in HTS are represented by a series of nodes that have quasi-static thermal hydraulic characteristics such as pressure and enthalpy, etc. Dynamic characteristics are delivered by the links between nodes, e.g., flow rate and pressure drop. The channel powers (decay heat), the secondary side pressure and the pressure at Reactor Inlet Header(RIH) are chosen as boundary conditions to describe the assumed initiating incidents for the iii model. With ongoing loss of inventory and system depressurization, vapor lock occurs in Steam Generator(SG), and it increases the pressure drop from Reactor Outlet Header(ROH) to RIH across SG and forms an increasingly negative RIH-to-ROH pressure differential. Flow reversal occurs in the channel due to the counter force balance between negative RIH-to-ROH pressure difference and the driving force derived from the density difference between the hot and cold legs. It is found that channels in row A have the highest reversal preference, then followed by the channels in row B, and in that order subsequently. Row A reverses when inventory decreases to about 79.5% of initial value, with following boundary conditions: decay heat is 1.5% of Full Power(FP) and secondary side pressure is 5.070 MPa. In addition, it is found that the decrease in channel power accelerates the depressurization process and brings forward the occurrence of flow reversal in fuel channels. / Thesis / Master of Applied Science (MASc)