http://hdl.handle.net/1721.1/7691 Thu, 23 May 2013 11:12:47 GMT 2013-05-23T11:12:47Z http://hdl.handle.net/1721.1/70654 Numerical applications of the generalized method of steepest descents Clarisse, Jean-Marie Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1992.; Includes bibliographical references (leaves 268-272). Wed, 01 Jan 1992 00:00:00 GMT http://hdl.handle.net/1721.1/70654 1992-01-01T00:00:00Z http://hdl.handle.net/1721.1/70641 Digital simulation of a transportation interface. Chryssostomidis, Chryssostomos Massachusetts Institute of Technology. Dept. of Naval Architecture and Marine Engineering. Thesis. 1970. Ph.D.; MICROFICHE COPY ALSO AVAILABLE IN BARKER ENGINEERING LIBRARY.; Vita.; Bibliography: leaves 198-200. Thu, 01 Jan 1970 00:00:00 GMT http://hdl.handle.net/1721.1/70641 1970-01-01T00:00:00Z http://hdl.handle.net/1721.1/69206 Analysis and interpretation of tidal currents in the coastal boundary layer May, Paul Wesley, 1950- Concern with the impact of human activities on the coastal region of the world's oceans has elicited interest in the so-called "coastal boundary layer"-that band of water adjacent to the coast where ocean currents adjust to the presence of a boundary. Within this zone, roughly 10 km wide, several physical processes appear to be important. One of these, the tides, is of particular interest because their deterministic nature allows unusually thorough analysis from short time series, and because they tend to obscure the other processes. The Coastal Boundary Layer Transect (COBOLT) experiment was conducted within 12 km of the south shore of Long Island, New York to elucidate the characteristics of the coastal boundary layer in the Middle Atlantic Bight. Analysis of data from this experiment shows that 35% of the kinetic energy of currents averaged over the 30 m depth are due to the semidiurnal and diurnal tides. The tidal ellipses, show considerable vertical structure. Near-surface tidal ellipses rotate in the clockwise direction for semidiurnal and diurnal tides, while near-bottom ellipses rotate in the counterclockwise direction for the semidiurnal tide. The angle between the major axis of the ellipse and the local coastline decreases downward for semidiurnal and increases downward for diurnal tides. The major axis of the tidal ellipse formed from the depth averaged semidiurnal currents is not parallel to the local shoreline but is oriented at an angle of -15 degrees. This orientation "tilt" is a consequence of the onshore flux of energy which is computed to be about 800 watts/m. A constant eddy viscosity model with a slippery bottom boundary condition reproduces the main features observed in the vertical structure of both semidiurnal and diurnal tidal ellipses. Another model employing long, rotational, gravity waves (Sverdrup waves) and an absorbing coastline explains the ellipse orientations and onshore energy flux as a consequence of energy dissipation in shallow water. Finally, an analytical model with realistic topography suggests that tidal dissipation may occur very close (2-3 km) to the shore. Internal tidal oscillations primarily occur at diurnal frequencies in the COBOLT data. Analysis suggests that this energy may be Doppler-shifted to higher frequencies by the mean currents of the coastal region. These motions are trapped to the shore and are almost exclusively first baroclinic mode internal waves. Thesis (Sc. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences and the Dept. of Meteorology; and the Woods Hole Oceanographic Institution), 1979.; Vita. Also issued in leaves.; Includes bibliographical references (p. [191]-197). Mon, 01 Jan 1979 00:00:00 GMT http://hdl.handle.net/1721.1/69206 1979-01-01T00:00:00Z http://hdl.handle.net/1721.1/69203 Dynamics of global ocean heat transport variability Jayne, Steven Robert A state-of-the-art, high-resolution ocean general circulation model is used to estimate the time-dependent global ocean heat transport and investigate its dynamics. The north-south heat transport is the prime manifestation of the ocean's role in global climate, but understanding of its variability has been fragmentary owing to uncertainties in observational analyses, limitations in models, and the lack of a convincing mechanism. These issues are addressed in this thesis. Technical problems associated with the forcing and sampling of the model, and the impact of high-frequency motions are discussed. Numerical schemes are suggested to remove the inertial energy to prevent aliasing when the model fields are stored for later analysis. Globally, the cross-equatorial, seasonal heat transport fluctuations are close to +4.5 x 1015 watts, the same amplitude as the seasonal, cross-equatorial atmospheric energy transport. The variability is concentrated within 200 of the equator and dominated by the annual cycle. The majority of it is due to wind-induced current fluctuations in which the time-varying wind drives Ekman layer mass transports that are compensated by depth-independent return flows. The temperature difference between the mass transports gives rise to the time-dependent heat transport. The rectified eddy heat transport is calculated from the model. It is weak in the central gyres, and strong in the western boundary currents, the Antarctic Circumpolar Current, and the equatorial region. It is largely confined to the upper 1000 meters of the ocean. The rotational component of the eddy heat transport is strong in the oceanic jets, while the divergent component is strongest in the equatorial region and Antarctic Circumpolar Current. The method of estimating the eddy heat transport from an eddy diffusivity derived from mixing length arguments and altimetry data, and the climatological temperature field, is tested and shown not to reproduce the model's directly evaluated eddy heat transport. Possible reasons for the discrepancy are explored. Thesis (Sc. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and Woods Hole Oceanographic Institution), 1999.; Includes bibliographical references (p. 161-169). Fri, 01 Jan 1999 00:00:00 GMT http://hdl.handle.net/1721.1/69203 1999-01-01T00:00:00Z