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Accurately mapping the evolving bathymetry under energetic wave breaking is challenging, yet critical for improving our understanding of sandy beach morphodynamics. Though remote sensing is one of the most promising opportunities for reaching this goal, existing depth‐inversion algorithms using linear approaches face major theoretical and/or technical issues in the surf zone, limiting their accuracy over this region. Here, we present a new depth‐inversion approach relying on Boussinesq theory for quantifying nonlinear dispersion effects in nearshore waves. Using high‐resolution datasets collected in the laboratory under diverse wave conditions and beach morphologies, we demonstrate that this approach results in enhanced levels of accuracy in the surf zone (errors typically within 10%) and presents a major improvement over linear methods. The new nonlinear depth‐inversion approach provides significant prospects for future practical applications in the field using existing remote sensing technologies, including continuous lidar scanners and stereo‐imaging systems. Plain Language Summary The coastal science community currently lacks insights into the morphological evolution of sandy beaches, including rapid changes that occur during storms. This is, to a large extent, explained by the difficulty to monitor the seabed elevation under such conditions in a region of the nearshore where high‐energy waves break. If a relationship can be established between observed wave dynamics at the surface and the water depth below, remote‐sensing technology presents a promising opportunity to reach this goal since it requires no physical interaction with the water environment. However, the existing algorithms to retrieve the water depth rely on the linear wave dispersion relation, which fails at describing the nonlinear dynamics of shoaling and breaking waves. Here, we develop a new depth‐inversion approach based on a Boussinesq theory, which better describes such dynamics. Using a range of wave conditions and beach morphologies, we demonstrate that our approach results in significant improvement compared to the classic approaches, achieving typical accuracy within 10% in regions of the nearshore where waves break. The new nonlinear depth‐inversion approach provides very promising prospects for future practical applications in the field using, for instance, high‐resolution datasets collected with lidar scanners or stereo imaging systems. Key Points A new depth‐inversion approach for the nearshore is proposed, based on a Boussinesq theory for quantifying nonlinear dispersion effects Unprecedented levels of accuracy (typically within 10%) are obtained in the surf zone over both planar and barred beaches Improvement over the linear wave theory method, which overestimates depths by 40% or more in surf zones (up to 80% at the shoreline)

Tidal-scale wave modulation is a critical yet complex process in macro-tidal estuaries. This study investigates semidiurnal wave modulations in the Changjiang River Estuary (CRE) using unique, long-term in situ observations and high-resolution ADCIRC–SWAN coupled simulations. Pronounced semidiurnal signals are identified in significant wave height (Hs), mean wave period, and wave direction. Observational results demonstrate that the modulation intensity is highest in Hangzhou Bay and the CRE mouth, decreasing gradually offshore. A key finding is that semidiurnal Hs maxima systematically coincide with peak flood currents and precede high water by approximately three hours. Long-term records confirm that this modulation persists year-round and intensifies during energetic events such as typhoons. The expression of the tidal signal depends on wave composition: wind-sea-dominated conditions exhibit stronger period modulation, whereas swell-dominated conditions favor coherent Hs modulation as kinematic tidal effects remain more apparent in the absence of strong local wind forcing. Numerical sensitivity experiments demonstrate that tidal currents are the primary driver of the observed wave modulation, while water-level effects are largely confined to shallow shoals. The results highlight that accurately reproducing the observed frequency–directional structure requires the inclusion of current-induced Doppler shifts and refraction. Beyond the classical following-current effects, the analysis suggests that the spatial deceleration of currents along the wave path acts as a kinematic trap that focuses wave action and sustains Hs intensification. This mechanism provides a physically plausible explanation for the observed phase relationship and points to the non-local nature of estuarine wave dynamics, where the wave state appears as an integrated response to cumulative current gradients along the propagation path. These findings emphasize the necessity of incorporating wave–current coupling in future coastal modeling and hazard forecasting.

During extended winter (November–April), 43% of the intraseasonal rainfall variability in China is explained by three spatial patterns of temporally coherent rainfall. These patterns were identified with empirical orthogonal teleconnection (EOT) analysis of observed 1982–2007 pentad rainfall anomalies and connected to midlatitude disturbances. However, examination of individual strong EOT events shows that there is substantial inter-event variability in their dynamical evolution, which implies that precursor patterns found in regressions cannot serve as useful predictors. To understand the physical nature and origins of the extratropical precursors, the EOT technique is applied to six simulations of the Met Office Unified Model at horizontal resolutions of 200–40 km, with and without air–sea coupling. All simulations reproduce the observed precursor patterns in regressions, indicating robust underlying dynamical processes. Further investigation into the dynamics associated with observed patterns shows that Rossby wave dynamics can explain the large inter-event variability. The results suggest that the apparently slowly evolving or quasi-stationary waves in regression analysis are a statistical amalgamation of more rapidly propagating waves with a variety of origins and properties.

In this article, we construct the exact dynamical wave solutions to the Date–Jimbo–Kashiwara–Miwa equation with conformable derivative by using an efficient and well-established approach, namely: the two-variable G’/G,  1/G-expansion method. The solutions of the Date–Jimbo–Kashiwara–Miwa equation with conformable derivative play a vital role in many scientific occurrences. The regular dynamical wave solutions of the abovementioned equation imply three different fundamental functions, which are the trigonometric function, the hyperbolic function, and the rational function. These solutions are classified graphically into three categories, such as singular periodic solitary, kink soliton, and anti-kink soliton wave solutions. Furthermore, the effect of the fractional parameter on these solutions is discussed through 2D plots.

A strong spring Wyrtki jet (WJ) presents in May 2013 in the eastern equatorial Indian Ocean. The entire buildup and retreat processes of the spring WJ were well captured by two adjacent Acoustic Doppler Current Profilers mounted on the mooring systems. The observed zonal jet behaved as one intraseasonal event with the significant features of abrupt emergence as well as slow disappearance. Further research illustrate that the pronounced surface westerly wind burst during late-April to mid-May, associated with the active phase of a robust eastward-propagating Madden-Julian oscillation in the tropical Indian Ocean, was the dominant reason for the rapid acceleration of surface WJ. In contrasting, the governing mechanism for the jet termination was equatorial wave dynamics rather than wind forcing. The decomposition analysis of equatorial waves and the corresponding changes in the ocean thermocline demonstrated that strong WJ was produced rapidly by the wind-generated oceanic downwelling equatorial Kelvin wave and was terminated subsequently by the westward-propagating equatorial Rossby wave reflecting from eastern boundaries of the Indian Ocean.

Following the 2010 Mentawai tsunami, observations in Sumatra by Hill et al. (J Geophys Res Solid Earth, 2012. https://doi.org/10.1029/2012jb009159) noted enhanced tsunami runup in coastal areas behind island chains. Many local communities in the region, however, falsely believed that islands provide shelter against tsunami waves. The present study aims to capture when and how island chains are amplifiers of wave energy in the coastal areas they shadow, which is often where coastal communities thrive. Physical modeling was carried out in the Directional Wave Basin at the Oregon State University O.H. Hinsdale Wave Research Laboratory. The experiment included four island configurations and three different waveforms a: solitary wave, error function wave and a leading depression N-wave. Results suggest that island chains can act as wave amplifiers, indicating potential amplification in both shoreline runup and current velocity. The amplification is, however, not consistent with every waveform. Also, in some cases, the impact of the offshore islands led to a reduction in coastal impacts. This result suggests that the offshore waveform plays an important role in the wave dynamics between the islands and on the wave uprush directly behind the islands.

A deterministic system of ocean surface waves and flow in the oceanic boundary layer is key to understanding the dynamics of the upper ocean. For the description of such complex systems, a higher‐order shear‐current modified nonlinear Schrödinger equation is newly derived and then used to physically interpret the interplay between Stokes drift, Eulerian return flow due to a passing wave group, and an open‐ocean vertically sheared flow in the extreme sea wave generation. The conditions for the suppression or enhancement of the modulation instability in the rogue wave dynamics in the presence of a background flow are reported, whose relevance and influence to the Craik‐Leibovich type 2 instability in triggering a Langmuir‐type circulation is discussed. The findings highlight the need for future studies to establish and assess the energy transfer from waves to currents or in the reversing order, asserting a plausible physical mechanism for the dissipation of the surface wave energy through wave‐current interactions in the open ocean. Plain Language Summary The dynamics of the upper‐ocean involve many complex processes, including for instance the interplay between wind, waves, currents, and global circulation systems. Such interactions can give rise to instabilities and extreme events with far‐reaching consequences. In this letter, we use a newly derived weakly nonlinear wave framework accounting for the presence of shear currents to quantify the requirements to trigger modulation instability, giving rise to long‐crested rogue waves. Our investigation also provides combined conditions for the occurrence of both, modulation and Craik‐Leibovich (type 2) instabilities, and demonstrates the possibility of energy transfers between waves as well as between waves and currents in the ocean. Key Points An advanced shear‐current modified nonlinear Schrödinger‐type equation is derived for surface waves in a background open‐ocean flow The interplay between Stokes drift, background flow, and Eulerian return flow by a wave group, in extreme waves generation is revealed How a background flow suppresses the modulational instability is explained and its relevance to the CL2 instability is discussed

The aim of the present study is to investigate the linear and nonlinear wave dynamics of a falling incompressible viscous fluid when the fluid undergoes an effect of odd viscosity. In fact, such an effect arises in classical fluids when the time-reversal symmetry is broken. The motivation to study this dynamics was raised by recent studies (Ganeshan & Abanov, Phys. Rev. Fluids, vol. 2, 2017, p. 094101; Kirkinis & Andreev, J. Fluid Mech., vol. 878, 2019, pp. 169–189) where the odd viscosity coefficient suppresses thermocapillary instability. Here, we explore the linear surface wave and shear wave dynamics for the isothermal case by solving the Orr–Sommerfeld eigenvalue problem numerically with the aid of the Chebyshev spectral collocation method. It is found that surface and shear instabilities can be weakened by the odd viscosity coefficient. Furthermore, the growth rate of the wavepacket corresponding to the linear spatio-temporal response is reduced as long as the odd viscosity coefficient increases. In addition, a coupled system of a two-equation model is derived in terms of the fluid layer thickness $h(x,t)$ and the flow rate $q(x,t)$. The nonlinear travelling wave solution of the two-equation model reveals the attenuation of maximum amplitude and speed in the presence of an odd viscosity coefficient, which ensures the delay of transition from the primary parallel flow with a flat surface to secondary flow generated through the nonlinear wave interactions. This physical phenomenon is further corroborated by performing a nonlinear spatio-temporal simulation when a harmonic forcing is applied at the inlet.

Flexural-gravity wave characteristics are analysed, in the presence of a compressive force and a two-layer fluid, under the assumption of linearized water wave theory and small amplitude structural response. The occurrence of blocking for flexural-gravity waves is demonstrated in both the surface and internal modes. Within the threshold of the blocking and the buckling limit, the dispersion relation possesses four positive roots (for fixed wavenumber). It is shown that, under certain conditions, the phase and group velocities coalesce. Moreover, a wavenumber range for certain critical values of compression and depth is provided within which the internal wave energy moves faster than that of the surface wave. It is also demonstrated that, for shallow water, the wave frequencies in the surface and internal modes will never coalesce. It is established that the phase speed in the surface and internal modes attains a minimum and maximum, respectively, when the interface is located approximately in the middle of the water depth. An analogue of the dead water phenomenon, the occurrence of a high amplitude internal wave with a low amplitude at the surface, is established, irrespective of water depth, when the densities of the two fluids are close to each other. When the interface becomes close to the seabed, the dead water effect ceases to exist. The theory developed in the frequency domain is extended to the time domain and examples of negative energy waves and blocking are presented.