Non linear internal waves modeling of their influence on acoustic mode energy fluctuations and characterization using SAR systems
Colosi, John A.
Durkee, Philip A.
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Non Linear Internal Waves (NLIW) are ubiquitous and appear wherever a proper combination of stratified water, current and bathymetry occur. In recent years, they have also been proven of primary interest for acoustic oceanography, since they are known to play an important role in sound speed fluctuations in shallow waters. The predictability of acoustic variability caused by these waves has been somewhat limited, and largely based on direct numerical simulation. Through this project, we present a simple and computationally efficient analytic model based on coupled mode theory. For this purpose, narrow and broadband acoustic normal mode fluctuations in the 2001 South China Sea ASIAEX experiment are first examined. Then ASIAEX environmental data are used to characterize the space/time scales of NLIW sound speed structure. Finally, a comparison is conducted between the observed normal mode variability and the predictions from an analytic model utilizing the observed NLIW structure, such as its width, amplitude and speed. As the model proves to be very sensitive to these characteristics, an overview of the Synthetic Aperture Radar capabilities to retrieve them is also conducted. In this latter part of the project, particular attention is given to wind effects on SAR data.
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