• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Analysis of topography induced flow variations along the Gao-Ping Submarine Canyon based on hydrographic observations

Gau, Ming-Shiung 29 April 2011 (has links)
This study investigates the hydrodynamic variations along the Gao-ping Submarine Canyon influence by the topography effects. The data used in this study were collected from two cruises of field observations using research vessel OR3. Instruments applied include sb-ADCP¡Bbm-ADCP¡Bmoored-ADCP¡BCTD and several vertical strings of temperature loggers. Parameters recorded include flow velocities, water temperature and tidal elevation. The analysis method is enlightenment by the case study in the Monterey Canyon of California. The results show that (1) the current speed in the lower layer is faster than that of upper layer, which is explained due to v-shape of topography and bottom-trapped effect of internal tide. This result is consistent with previous studies. (2) In flood tide, the currents flowed into the Canyon from deep water to shallower. The baroclinic kinetic energy decreased to 0.2 at the turning point of canyon axis at 230m water, whichwas caused mainly by bottom friction. On the other hand, the baroclinic kinetic energy increased to 0.47 at 250m water in ebb tide when there was less influence of bottom friction. (3) In comparison the effects of bottom slope and area of cross section of the canyon, the baroclinic kinetic energy dissipation was mainly occurred at up slope flow during the flood tide. The change of the canyon width had less influence. During the ebb, the baroclinic kinetic energy was mainly due to the change of canyon width in the region shallower then the 230m of the second turning of the canyon. (4) The loss of kinetic energy during flooding up slope current can be verified by the changes of water mass temperature. Cold bottom was raised to upper layer when there was large drop of kinetic energy. There was likely a conversion of kinetic energy to potential energy. No upwelled cold water detected during ebb current with increase of kinetic energy.
2

The topography effect to the flow variation in the coastal region of Nan-bin,Hualien

Chang, Yu-Hung 21 October 2011 (has links)
This study investigates the hydrodynamic variations in the coastal region of Nan-bin, Hualien influence by the topography and water stratification. The data used were collected from four cruises of field observations in 2008/4/29¡B2008/9/5~6¡B2009/3/17~18 and 2009/7/21. Instruments applied include sb-ADCP and CTD. Parameters recorded include flow velocities, water temperature and salinity and tidal elevations. The collected data are analyzed through a variety of time series analysis technique, including buoyancy frequency EOF analysis, potential vorticity and kinetic energy. The results show that (1) the flow field and vorticity in the south side of Hualien Harbor indicate there exist a counterclockwise eddy during flood. The flow pattern reverse to be a clockwise eddy during ebb. The current speed and vorticity is smaller in the surface layer, while the bottom current speed and vorticity is much larger. (2) Currents in transects of along slope, along canyon and along shore all reveal two layers flow separated around 25m, with upper layer flowing eastward and lower layer westward. The current velocity reaches to a maximum at 55m, and the current directions were dominated by the orientation of bottom topography. The baroclinic kinetic energy increase to 0.15m2/s2 along the down slope transect, while the up slope kinetic energy reduced to 0.05m2/s2. (3) The CTD data suggest that the upper layer is warm-fresh water due to river outputs, while the lower layer is dominated by cold-salty open ocean water. (4) The density interface at 25 m is confirmed by buoyance frequency analysis. The EOF analysis of density distribution shows eigenvalue of first mode has maximum at 53m, while the second mode has peaks at 25m and 65m, which match well with the vertical of distribution of flow structures.

Page generated in 0.0568 seconds