|Author's Email Address
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|Type of Document
||Effects of bottom topography and flows on oceanic turbulent mixing|
|Date of Defense
||This study investigates the turbulent mixing characteristics of Peng-hu Channel, |
South China Sea along 21°N and the Kuroshio region by using CTD/LADCP and
MicroRider. Dissipation rate of turbulent kinetic energy or thermal variances is
estimated primarily by the Thorpe overturn method, and is compared with the
microstructure turbulence from direct measurement as well as those estimated from
the parameterization method based on shear and strain spectra.
Our results indicate that there are different turbulent characteristics and dynamic
mechanisms at these three regions. Because of its funnel-shaped topography and strong
semi-diurnal tides in the Peng-hu Channel, the turbulent mixing and eddy diffusivity
reach a maximum value at the narrowest part of Peng-hu Channel near its sea bottom
and show a clear tidal variation.
In the main stream of Kuroshio where the current speed is faster than 0.8 m/s,
turbulent mixing is not particularly stronger than non-main stream zone. In the
Kuroshio frontal zone between the Kuroshio and the coastal waters off east Taiwan
coast, strong turbulent mixing in the surface layer can be detected. Island wake which
is formed when Kuroshio runs into the Lan-yu Island is a transient feature. Strong
mixing in the upper 100 m accompanied with upwelling and vortices were observed
during one event.
The topography along the latitude of 21°N is rugged and rough in the Luzon
Strait which consists of several ridges and seamounts. Due to its complicated
topography and generation of strong semi-diurnal internal tides, eddy diffusivity as
high as 10^(-2)m^2/s was measured in the bottom layer of the Luzon Strait.
||Yiing-Jang Yang - chair|
I-Huan Lee - co-chair
Yu-Huai Wang - co-chair
Ruo-Shan Tseng - advisor
indicate access worldwide|
|Date of Submission