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Many internal wave-wave interaction patterns have been observed in satellite images. However, very few studies have been made on understanding these patterns. Internal wave interactions may result in exceptionally large amplitudes in the interaction zone, which, in turn, pose threats to underwater structures. In this paper, we analyze the characteristics of interaction patterns observed in satellite images of the Mid-Atlantic Bight, such as internal wave phase shifts and amplitude changes. Based on these characteristics, we categorize the patterns 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. We provide a detailed analysis of one observed interaction pattern within each category and compare our findings with existing analytical and numerical models for a two-soliton interaction. One important result from this study of interaction patterns is that the patterns alone can be used to deduce how the amplitude changes in the potentially hazardous interaction zone. This paper thus proves that high-resolution satellite images can provide a useful and efficient means of studying internal wave interaction. [ABSTRACT FROM PUBLISHER]

Satellite images have long been used to study surface manifestations of internal waves (IWs). More recently, marine X-band radar data have been employed to retrieve IW packet parameters. Marine radars have the advantage over satellite systems that their high temporal resolution enables the study of the IW evolution. Until today, no method to automatically detect IW surface signatures in marine radar data has been suggested. In this paper, we present a new fully automated tool to retrieve IW signatures from marine radar image sequences. First, after various preprocessing steps, the IW packet velocity is determined using a combination of localized Radon transform and cross-correlation techniques. Temporal averaging of the marine radar data significantly enhances the IW signatures. The knowledge of the IW packet velocity is used to correct for the IW motion, enabling us to extend the averaging period, which further enhances the IW signal. An IW-motion correction is necessary because, otherwise, the IW signal would become smeared if the averaging period were much longer than the time it takes the IW to propagate between radar resolution cells. The IW-enhanced images are then utilized for the IW signature analysis. Here, we identify local backscatter peaks and exploit the marine radar's high temporal resolution to distinguish signal from noise. The resulting series of IW soliton maps provides information on changes in soliton wavelength, velocity, and backscatter intensity. Our marine radar IW signature analysis tool therefore offers a great opportunity of studying the spatiotemporal evolution of IWs as they grow and decay. [ABSTRACT FROM AUTHOR]

The accurate estimation of internal solitary waves' (ISWs') amplitudes from radar images is important for understanding the ISW evolution, energy dissipation, and mixing processes. The in situ data from the Non-Linear Internal Wave Initiative experiment in the Mid-Atlantic Bight show many ISWs with amplitudes of 10 m or more in a shallow water depth of 80 m or less. Therefore, the higher order Korteweg–de Vries (KdV) equation in a two-layer system is needed to describe these large-amplitude ISWs instead of the classic KdV equation. Based on a simple theoretical radar imaging model, we develop a method 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. Two groups of ISWs with large amplitudes, determined from the temperature records from nearby moorings, are observed in a RADARSAT synthetic-aperture-radar image and in marine X-band radar data collected during the experiment. We validate the method using the ISW signatures taken from these two cases. We find the estimated amplitudes to agree well with those determined from the moorings. The proposed method provides a relatively simple and accurate way to estimate large ISW amplitudes from radar images. [ABSTRACT FROM AUTHOR]