High-resolution internal solitary wave simulations of shoaling and sand dune formation
Abstract
Abstract: High-resolution internal solitary wave simulations of shoaling and sand dune formationThis proposal focuses on the dynamics of internal solitary waves (ISW) in the South China Sea (SCS) which are among the largest in the world. Measurements on the SCS shelf indicate the presence of pronounced sand dunes that are hypothesized to be generated by the ISWs, yet no studies have confirmedthe mechanisms behind their formation. The first objective of this proposal is to understand the relationship between the sand dunegeometry and the properties of ISWs and internal tides using numerical simulations. While many numerical modeling studies have focused on the ISW dynamics in the SCS, there continues to be a lack of understanding of the three-dimensional processes governing ISW shoaling on the continental shelf. The second objective of the proposal is to conduct accurate, high-resolution numerical simulationsto understand the shoaling process. As part of this objective, we will develop methods to quantify the uncertainty of ISW predictions and quantitatively compare the simulations to SAR satellite imagery to better validate the simulated, three-dimensional shoaling dynamics. Numerical simulations will be conducted to study the relationship between the ISW parameters and the length and height of the dunes in flat-bottomed, periodic domains. The effects of both locally and remotely generated internal tides will be assessed in domains with linear shelf-slope bathymetry with critical and non-critical slopes with respect to the internal tide. The source of the spatial heterogeneity of the dunes in the SCS will be studied through simulations of different ISWs at different depths as they shoal onto the continental shelf. To accomplish the second objective, an accurate, high-resolution model will be developed to simulatethe evolution of ISWs in the SCS from generation in the Luzon Strait to transformation and eventual decay on the continental shelf.Computational requirements needed to accurately compute ISW shoaling will be assessed via comparison of two- and three-dimensional simulations to in-situ observations, and the uncertainty in predicting the ISWs will be evaluated using methods in uncertainty quantification. Finally, methods will be developed to quantitatively compare the ISW simulations to SAR imagery to validate the simulatedspatial variability of the ISWs.If successful, the proposed research will lead to an understanding of the formation of sand dunes by ISWs and internal tides, including the relationship between the waves and the sand dune length and height as well as how shoaling ISWs impact their spatial heterogeneity. The research will also lead to an accurate simulation tool that is capable of simulating ISW dynamics over much of their life cycle in domains like the SCS. The evolution of the ISWs will be validated quantitatively againstSAR satellite imagery, and methods will be developed to identify the dominant sources of uncertainty in the ISW predictions.Ocean acoustic signals involved in communications and sonar systems are highly sensitive to bottom bedforms and the spatio-temporal structure of the stratification, both of which are affected by ISWs and internal tides. Therefore, improved modeling capabilities of internal gravity wave processes acting over many scales, including their impact on sand dune formation, improve predictive capability of acoustics critical to naval operations in open ocean and coastal waters.Approved for Public Release.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142412707
Entities
People
- Oliver Fringer
Organizations
- Office of Naval Research
- Stanford University
- United States Navy