High-Resolution, Nonhydrostatic Simulations of Internal Wave Generation in the Luzon Strait using SUNTANS
Abstract
The primary objective of this study is to understand the mechanisms leading to the generation of internal waves in the South China Sea by performing high-resolution, nonhydrostatic numerical simulations with the SUNTANS model. A secondary objective is to perform simulations to aid with the planning of the field experiments for the Internal Waves in Straits Experiment (IWISE) DRI. We have developed a linear theory for the generation of internal waves over ridges to determine the phase in the tide at which peaks in the depression waves cross the ridges. The theoretical analysis that we have developed is based on the hypothesis that the generation mechanism is dominated by linear processes, and this is based on the evidence that wave arrival time at a particular mooring in the basin is roughly the same relative to the phase in the particular tide that generated that wave. That is, diurnally-generated A-waves arrive at mooring S7 at the same time every day, while semidiurnally-generated B-waves arrive roughly one hour later each day. This implies that the hydraulic effects at the generation site are weak and that nonlinear effects on the propagation speed are also weak. This justifies the development of a linear model, which is further simplified by assuming that the internal tides are generated and propagate predominantly as first-mode waves. This is based on evidence both from modeling and observations that more than 90% of the internal tidal energy in the Luzon Strait is in the first mode. The linear model is derived from the inviscid equations of motion with the Boussinesq approximation for a two-layer fluid with upper-layer depth d1 and lower-layer depth d2. We hypothesize that the linear theory will show that a two-ridge system can lead to left-propagating waves that are generated during peak ebb tides over the eastern ridge, and that nonlinear effects are not significant in altering this behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2009
- Accession Number
- ADA527200
Entities
People
- Oliver Fringer
Organizations
- Stanford University