Ocean waves theory and modeling
MEPLab
This research direction relates to advancing the mathematical modelling and physical understanding of linear and nonlinear wave-wave, wave-bottom and wave-current interactions.
Linear and nonlinear shoaling
Linear and nonlinear shoaling are two of the main mechanisms that change the wave spectrum in the near-shore region. The nonlinear mechanism is still not well understood and no mathematical formulation that can adequately allow its inclusion in stochastic wave action equation models, was derived (see e.g., Vrecica and Toledo, 2016,2019). This is one of the main discrepancies in using wave forecasting models in the near-shore region. Wave reflection is an example of a linear property that we developed to be included in operational wave models (see Yevnin and Toledo, 2018, 2021).
Infra-gravity waves
Infra-gravity (IG) waves are long ocean surface waves with periods of 25-250 sec that are not generated directly from the wind but due to nonlinear interactions mostly in the process of wave shoaling or wave breaking. In the nearshore region they can be dominant in the water motion particularly during storms. They have a significant influence on many nearshore processes such as coastal morphodynamics, coastal flooding, seiches of natural bays and harbour agitations. The main long-term goal of the research is to better understand the underlying nonlinear physics of their generation and to extend wind-wave forecasting models to forecast IG waves in regional and global scales. In Vrecica et al. (2019), for example, we found new nonlinear mechanisms to generate IG waves in the deep ocean connecting wind waves with wind gusts.
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Low frequency waves and shelf oscillations​
​Different instruments for observing surface sea level variability had been deployed in Haifa Bay, North of Israel. In addition to expected changes caused by tidal forces and atmospheric influence, the observations revealed significant and persistent oscillations with wave periods of 1 hour and 30 minutes. This means that the average sea level in this area has been changing much more frequently and is less predictable than previously thought. By using analytic explanations and numerical simulations we show that these oscillations are observable due to natural amplification that happens on the continental shelf, the relatively shallow region between Haifa promontory and Achziv Canyon. This intensification reaction could constitute a threat to the coastal area in an event of tsunami event or extreme weather conditions, which are known to generate waves in the same frequency range.​
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Wave-current interactions
Ambient currents have a significant effect on wave propagation. They cause refraction, diffraction, reflection, blocking, and Doppler shifts. Vertically shearing currents even change the wave’s vertical structure and dispersion relation. We use this theory to advance the formulation used in wave forecasting models, measurement methodologies of HF- and X-band radars, and In-situ measurement devices.​
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