Mechanisms and variability of salt transport in partially-stratified estuaries

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2000The variability of salt transport determines the variation of the length of the salinity intrusion and the large-scale density gradient in an estuary. This thesis contains three studies that address salt transport and the salt balance. The variation of salt transport with the depth, the along-channel salinity gradient, and the amplitude of the tidal velocity is investigated with analytic and numerical models. The results indicate that salt transport increases dramatically during stratified periods when vertical mixing is weak. Analysis of salt transport from observations in the Hudson Estuary show that stratified periods with elevated estuarine salt transport occur in five-day intervals once a month during apogean neap tides. Oscillatory salt transport, which is hypothesized to be primarily caused by lateral exchange and mixing of salt, appears to play a more minor role in the salt balance of the estuary. The salt balance of the estuary adjusts very little to the spring-neap modulation of salt transport but adjusts rapidly to pulses of freshwater flow. A simple model is used to investigate the process and time scales of adjustment of the salt balance by connecting variations of salt transport to the variations of freshwater flow and vertical mixing. The results show the length of the salinity intrusion adjust via advection to rapid and large increases in freshwater flow. The salinity intrusion adjusts more rapidly to the spring-neap cycle of tidal mixing the higher the freshwater flow.The National Science Foundation provided support through a National Science Foundation Graduate Fellowship and NSF Grant OCE94-15617. Grants from the Hudson River Foundation (HRF Grant 006j96A) and the Office of Naval Research (Grant Number N00014-97-1-0134) have also contributed towards the work in this thesis. This work is also partially the result of research sponsored by NOAA National Sea Grant College Program Office, Department of Commerce, under Grant No. NA46RG0470, Woods Hole Oceanographic Institution (WHOI) Sea Grant project no. R/O-30

Do Scandals Affect YOU as an Athletic Sportswear Consumer?

Athletic sportswear brands endorse celebrity-athletes to promote the brand’s image and gain credibility by having these ‘experts’ associated with their brand. This marketing technique is often advantageous for sportswear companies. However, there may be liabilities and complications for the brand if the endorsed athlete becomes involved in a scandal. The two main purposes of this thesis are to assess how and if consumer-purchasing behaviour is affected by endorsed celebrity-athletes involved in a scandal, and at what point should these athletes' contracts be terminated by the brand, from a consumer’s perspective. This may offer companies with insightful information to make informed decisions in such circumstances. A mix-method approach is used to examine consumers’ purchasing behaviour and opinion. The main method of data collection was an online questionnaire. The questionnaire was supplemented by interviews. The general findings of the overall study regarding consumer-purchasing behaviour after a scandal show that consumers perceived the criminal, non-sports related scandals to have the most effect on their purchasing behaviour. The sports related scandals are the next set of scandals seen to have a significant effect on consumers. Lastly, the less criminal, non-sports related scandals are considered to have the lowest effect on consumer purchasing behaviour. In terms of the termination of the athlete’s contract, the general findings correlate with the opinions on the severity of the scandal. When the sample consumers believe they would continue to purchase, they also believe the brand should not terminate the contract, and vice versa. Therefore, these findings may hopefully guide sportswear companies to make informed decisions and avoid unwanted repercussions

Performance Pressure and Resource Allocation in Washington

Based on interviews with state, district, and school officials, explores how performance pressures have changed resource allocation decisions. Examines reform goals and how Washington's finance system impedes efforts to link resources to student learning

Charter-School Management Organizations: Diverse Strategies and Diverse Student Impacts

Examines the growth of charter school management organizations, characteristics of students served, and use of resources; CMO practices; impact on students, including middle school test scores; and structures and practices linked to positive outcomes

Discovering the Data of Safety: Embry-Riddle’s Aviation Safety and Security Archives

The path to the sky and beyond has not been simple or obstacle-free, but dedicated dreamers have worked to overcome obstacles, learn from mishaps, and develop new technologies to achieve their goals. As the leading university for aviation and aerospace education, Embry-Riddle Aeronautical University maintains a firm commitment to the practice and study of safety. As part of this mission, the university has established the Aviation Safety and Security Archives (ASASA) which is a national treasure of aviation safety history and information

A Beautiful Thing: A Service Learning Partnership Develops

This roundtable presents multiple perspectives on a multi-year partnership between an urban school and its university neighbor. Building and nurturing a thriving mutually beneficial partnership between an urban Pre-K-8 school and its neighboring university is, as the principal of Cesar Batalla School often says, “a beautiful thing.” Cesar Batalla, serving 800 students and families from a multilingual, multiethnic community in a low-income neighborhood, is located a stone’s throw from a mid-sized suburban, private university that attracts undergraduate and graduate students with little personal firsthand experience with racial, ethnic and linguistic diversity, or of poverty and its challenges. “Geographical neighbors, yet worlds apart” would aptly describe the university school juxtaposition before we embarked upon our partnership. Transforming a coincidental proximity into a deep partnership has been a journey of many discoveries

The role of tides in bottom water export from the western Ross Sea

Approximately 25% of Antarctic Bottom Water has its origin as dense water exiting the western Ross Sea, but little is known about what controls the release of dense water plumes from the Drygalski Trough. We deployed two moorings on the slope to investigate the water properties of the bottom water exiting the region at Cape Adare. Salinity of the bottom water has increased in 2018 from the previous measurements in 2008–2010, consistent with the observed salinity increase in the Ross Sea. We find High Salinity Shelf Water from the Drygalski Trough contributes to two pulses of dense water at Cape Adare. The timing and magnitude of the pulses is largely explained by an inverse relationship with the tidal velocity in the Ross Sea. We suggest that the diurnal and low frequency tides in the western Ross Sea may control the magnitude and timing of the dense water outflow

Stress, salt flux, and dynamics of a partially mixed estuary

A field study was performed in the lower Hudson River, a partially mixed estuary with a relatively simple geometry (Figure 1), between August and October of 1995. The objectives of the study were (1) to quantify and characterize the turbulent transport of momentum and salt, and (2) to relate the turbulent transport processes to the local and estuary-wide dynamics. The measurement program consisted of fixed and shipboard components. At a central site, a moored array of temperature-conductivity sensors and optical backscatter sensors (OBS), a bottom-mounted acoustic Doppler current profiler (ADCP), and a bottom-mounted array of acoustic travel-time current sensors (BASS), temperature-conductivity sensors, and OBS sensors resolved the vertical structure of velocity, salinity and turbidity and the near-bottom turbulence structure. Moored and bottom-mounted velocity, temperature, conductivity and pressure sensors at five secondary sites quantified the spatial and temporal variabilty of velocity, salinity and bottom pressure. Shipboard measurements with an ADCP and a conductivity-temperature-depth (CTD) profiler, accompanied by an OBS sensor, resolved the spatial structure and tidal variability of velocity, salinity and turbidity along several cross-channel and along-channel transects. This report describes the measurements in detail. Section II describes the instrumentation, Section III describes the deployment and sampling schemes, Section IV describes the data processing, and Section V is a summary of plots of selected data. Section VI documents the data files and Sections VII and VII give acknowledgments and references.Funding was provided by the National Science Foundation under Grant OCE-94-15617 and The Hudson River Foundation