Publication Date

2013-12-13

Availability

Open access

Embargo Period

2013-12-13

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Applied Marine Physics (Marine)

Date of Defense

2013-11-12

First Committee Member

Hans C. Graber

Second Committee Member

Michael G. Brown

Third Committee Member

Roland Romeiser

Fourth Committee Member

Karl R. Helfrich

Abstract

Satellite imagery has been widely used to study internal solitary wave (ISW) generation mechanisms, evolution, and properties. The Nonlinear Internal Wave Initiative/Shallow Water 2006 (SW06) experiment in the Mid-Atlantic Bight (MAB) provided a unique dataset to study the vertical structure from their surface manifestation in the images, which can improve our understanding of ISW evolution, energy dissipation, and mixing processes. This thesis has two parts. First, the applicability of various weakly nonlinear theories including the Korteweg-de Vries (KdV), Intermediate Long Wave (ILW), Benjamin-Ono (BO), and higher-order KdV models is tested to describe large amplitude ISWs in the MAB. Based on a simple theoretical radar imaging model, a method is developed to estimate large ISW amplitudes from distances between the positive and negative peaks of ISW signatures in radar images and a selection rule from the two possible amplitude solutions is proposed. Two groups of ISWs with large amplitudes, determined from the temperature records from nearby moorings, are observed in a RADARSAT-1 synthetic-aperture-radar (SAR) image and in marine X-band radar data collected during the experiment. The proposed method is validated by using the ISW signatures taken from these two cases. The estimated amplitudes using the higher-order KdV model are found to agree well with those determined from the moorings. All other models give amplitude estimates that are far too small. Second, the characteristics of the observed interaction patterns in the satellite images such as wave phase shifts and amplitude changes are analyzed. Comparing these patterns with existing analytical and numerical models for a two-soliton interaction, these patterns are categorized into four different types: Mach interaction; regular interaction with prominent positive phase shifts and an amplitude decrease in the interaction zone; regular interaction with prominent negative phase shifts and an amplitude increase in the interaction zone; and wave interactions without phase shifts. One important result from this study is that the patterns alone can be used to deduce how the amplitude changes in the potentially hazardous interaction zone, which demonstrates that high-resolution satellite images can provide a useful and efficient means of studying internal wave interaction.

Keywords

Satellite images; internal solitary waves; wave-wave interactions; Mid-Atlantic Bight

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