To describe large amplitude internal solitary waves in a two-layer system, we consider the high-order unidirectional (HOU) model that extends the Korteweg–de Vries equation with high-order nonlinearity and leading-order nonlinear dispersion. While the original HOU model is valid only for weakly nonlinear waves, its coefficients depending on the depth and density ratios are adjusted such that the adjusted

A two-dimensional, vertical section of the Strait of Gibraltar is simulated numerically with the nonhydrostatic/non-Boussinesq three-dimensional CROCO model to investigate details of small-scale dynamics. The proposed configuration is simple, computationally efficient and incorporates the configuration of sills characteristic of this region. Despite the shortcomings of a 2D representation, this configuration

The unstructured mesh, discontinuous Galerkin finite element discretisation based coastal ocean model, Thetis, has been extended to include non-hydrostatic (buoyancy-driven and free surface) dynamics. Two alternative approaches to achieve this are described in this work. The first (a 3D based algorithm) makes use of prismatic element based meshes and uses a split-step pressure projection method for

Accurate representation of vertical turbulent fluxes is crucial for numerical ocean modeling, both in global and coastal applications. The state-of-the-art approach is to use two-equation turbulence closure models which introduces two dynamic equations to the system. Solving these equations numerically, however, is challenging due to the strict requirement of positivity of the turbulent quantities

This study is concerned with the characteristics of coherent vortices within the turbulent air flow undulated by gravity and capillary–gravity water waves. The flow fields from the direct numerical simulations are analyzed. A formal scheme is developed to detect and classify the vortical structures. The scheme uses local analysis of the velocity-gradient tensor to define the vortex swirling core, and

The water masses exiting the Labrador Sea, and in particular the dense water mass formed by convection (i.e. Labrador Sea Water, LSW), are important components of the Atlantic Meridional Overturning Circulation (AMOC). Several studies have questioned the connection of the LSW production to the AMOC variability. This is partly due to the limited understanding of how this locally formed water mass leaves

The 200m-thick surface layer of the Arctic Ocean contains a lower salinity part in the Canadian Basin, receiving fresher water from the Pacific Ocean as well as rivers, and also a higher salinity part in the Eurasian Basin, receiving saltier water from the Greenland Sea. This surface layer receives atmospheric forcing, and also partially mixes with the subsurface layer. Thus, thermohaline circulation

Three-dimensional (3D) obstacles on the bottom are common sites for the generation of vortices, internal waves and turbulence by ocean currents. Turbulence-resolving simulations are conducted for stratified flow past a conical hill, a canonical example of 3D obstacles. Motivated by the use of slip boundary condition (BC) and drag-law (effectively partial slip) BC in the literature on geophysical wakes

In this study, we expand previous large eddy simulation (LES) modeling investigations of Langmuir turbulence (LT) to real ocean conditions using field observations collected under the multi-platform field campaign “Coupled Air–Sea Processes and Electromagnetic (EM) ducting Research (CASPER-East)”. The measurement site has strong local variabilities of temperature and salinity and experienced large

The quality of metocean forecasts at longer forecast ranges has a significant impact on maritime safety and offshore operations. A nonlinear ensemble averaging technique is demonstrated using neural networks applied to one year (2017) of Global ocean Wave Ensemble forecast System (GWES) data provided by NCEP. Post-processing algorithms are developed based on multilayer perceptron neural networks (NN)

We study the 2D turbulent mixing of a passive scalar in the ocean mixed layer. As an example, we examine a steady-state convective mixed layer in which the boundary conditions are chosen so that the system reaches a dynamical equilibrium. In this idealized case, we parameterize the horizontally and temporally averaged fluxes as a functional of the horizontally and temporally averaged property gradients

A coastal ocean model is presented, adapting the unstructured C-grid discretisation (Ringler et al., 2010) employed in the MPAS (Model for Prediction Across Scales) global ocean model for use in an existing structured coastal modelling framework. Specifically, the discretisation of momentum advection, horizontal viscosity, Coriolis and continuity due to Ringler et al. are used; remaining terms are

River plume source-front connectivity, or the relationship between processes at the source, plume body and front, is investigated with numerical simulations of the Merrimack River plume using the Regional Ocean modeling System (ROMS). Source water, i.e. water discharged from the estuary during an ebb pulse, overtakes the front as it propagates offshore, resulting in the strong convergence that exists

Dynamical climate models have been extensively used over the last decade to perform seasonal sea ice predictions in the context of ensemble forecasting. To date, the sensitivity to the initial conditions has received the most attention through the evaluation of the theoretical limit of Antarctic sea ice predictability imposed by the chaotic evolution of the climate system. The respective contributions

In this study, we investigated the short-term dynamics of upwelling off the west coast of Hainan Island (UWH) by combining Moderate Resolution Imaging Spectroradiometer (MODIS) infrared sea surface temperature (SST) images and Regional Ocean Modeling System (ROMS) simulations. MODIS observations showed that the UWH could exhibit rapid temporal variations, where the SST could increase or decrease by

Representing the net freshwater flux at river mouths is challenging for global and regional scale ocean modelling. Although rivers are well known to affect both the coastal and basin-wide circulation and dynamics, coarse resolution ocean models cannot resolve the estuarine dynamics and are usually forced at river outlets in a simplistic way, with climatological runoff and zero or constant salinity

The model of coastal waves based on the depth-averaging of the large eddy simulation equations (Kazakova and Richard, 2019) is extended to the case of regular and irregular wave trains. To take into account a stronger turbulence, the third moment of the horizontal velocity is modelled with a gradient-diffusion hypothesis. The effect of this new diffusive term is to smooth and regularize the solutions

In this paper, we explore the secondary flows in the Danish Straits using observations and numerical simulations performed with the unstructured-grid hydrodynamic model SCHISM covering the North Sea and Baltic Sea. The straits are resolved on scales of up to ∼100 m. Given that large-scale atmospheric variability dominates the transport in these straits, we focus on the processes with subtidal time

Baroclinic eddy restratification strongly influences the ocean’s general circulation and tracer budgets, and has been routinely parameterized via the Gent-McWilliams (GM) scheme in coarse-resolution ocean climate models. These parameterizations have been improved via refinements of the GM eddy transfer coefficient using eddy-resolving simulations and theoretical developments. However, previous efforts

Open-ocean deep convection (DC), forming a link between the upper and the deep ocean dynamics, is observed in a few localized sites of the World Ocean. In the present paper, we further develop an analytical model of isolated vertically homogenized water columns, up to a few kilometers deep, usually referred to as convective chimneys. We derive analytical solutions for evolution of a chimney during

Understanding ice shelf-ocean interaction is fundamental to projecting the Antarctic ice sheet response to a warming climate. Numerical ice shelf-ocean models are a powerful tool for simulating this interaction, yet are limited by inherent model weaknesses and scarce observations, leading to parameterisations that are unverified and unvalidated below ice shelves. We explore how different models simulate

Rip currents arise from the momentum flux associated with depth-induced breaking of incident surface gravity waves on beaches with irregular bottom topography. In 3D simulations with an idealized topographic configuration, uniform density, and a steady incident wave field, a striking enhancement of transient surf eddy variability occurs over irregular topography compared to smooth topography, especially

We investigated the performance of a tidally and subtidally forced open boundary condition (TST-OBC) on the estuarine-shelf circulation in a limited-area, down-scaling numerical modeling system for the northern South China Sea. We forced the modeling system with amplified tidal forces and subtidal forcing of spatiotemporally variable wind and river discharge. TST-OBC numerically and physically accommodates

As climate models move towards higher resolution, their ocean components are now able to explicitly resolve mesoscale eddies. High resolution for ocean models is roughly classified into eddy-present (EP, ∼1/4°) and eddy-rich (ER, ∼1/12°) resolution. The cost-benefit of ER resolution over EP resolution remains debated. To inform this discussion, we quantify and compare the surface properties of coherent

Abundant and diverse cold-water coral and fish communities can be found in the deep waters of the Florida Straits, which are believed to be living under suboptimal conditions impacted by increasing oceanic CO2 levels. Yet, little is known regarding the spatial–temporal variability of bottom carbonate chemistry parameters and their dynamic drivers in this area. To address this issue, we present results

In this article, we propose an inverse technique that accurately reconstructs the ocean’s density stratification profile simply from free surface elevation data. Satellite observations suggest that ocean surface contains the signature of internal tides, which are internal gravity waves generated by the barotropic tides. Since internal tides contain the information of ocean’s density stratification

JRA55-do, the new atmospheric dataset for driving ocean–sea-ice models based on the Japanese 55-year atmospheric reanalysis (JRA-55), has been recently proffered for use in future ocean–sea-ice hindcast simulations, including those under the Ocean Model Intercomparison Project (OMIP) umbrella, thereby replacing the Coordinated Ocean-ice Reference Experiments (CORE) interannual forcing dataset. The

In this study, observational data together with the simulations from a high-resolution numerical ocean model are used to identify the processes responsible for the anomalous warm sea surface temperature (SST) over the equatorial Indian Ocean during late spring/early summer in 2007. Our analysis suggests that the SST in the western equatorial Indian Ocean (WEIO) remained unusually warm owing to the

We investigate the stability of a composite cyclone representative of Arabian Sea eddies using a high resolution primitive equation model. We observe that the eddy is unstable with respect to a mixed barotropic/baroclinic instability, leading to the growth of an azimuthal mode 2 perturbation. The latter deforms the eddy, which eventually evolves into a tripole after about 4 months of simulation. The

A year-long Four-Dimensional Variational (4D-Var) data assimilation experiment, formulated on the physical-space statistical analysis system (PSAS) algorithm, has been applied to the Adriatic Sea for the very first time. High-resolution multi-platform observations were assimilated into the Regional Ocean Modeling System (ROMS) forced by mesoscale atmospheric model ALADIN/HR (Aire Limitée Adaptation

The Black Sea is one of the largest land-locked basins in the world. Due to the vulnerability of its unique marine ecosystem, accurate long-term modelling of its hydrodynamics is needed. In this study, we first compare the skills of four NEMO based Black Sea models in a free-run which use different discretization schemes. We find that the most accurate results are obtained with the model (named CUR-MEs)

An ice shelf module is implemented into the unstructured-grid, three-dimensional primitive equation Finite Volume Community Ocean Model (FVCOM) for studying ice shelf-ocean interactions along the complex and irregular geometry of the coastal ocean. Pressure gradient errors associated with the representation of the ice shelf geometry in the model’s terrain-following vertical coordinate are investigated

Rapidly melting sea ice processes during the summer tend to enlarge the open water in the Arctic region. The resulting larger potential fetch for surface waves can allow significant wave generation and development in the region. The sea ice plays an energy dissipation role for waves propagating into the ice-covered sea. A spherical-coordinate surface wave model was established within the unstructured

Accurate and stable implementation of bathymetry boundary conditions remains a challenging problem. The dynamics of ocean flow often depend sensitively on satisfying bathymetry boundary conditions and correctly representing their complex geometry. Generalized (e.g. σ) terrain-following coordinates are often used in ocean models, but they require smoothing the bathymetry to reduce pressure gradient

The role of open boundary conditions in modelling the seasonal variation of the North Equatorial Current Bifurcation latitude (NBL) is studied based on a linear Rossby wave model, 1.5-layer reduced-gravity model and Hybrid Coordinate Ocean Model (HYCOM). For a regional ocean model that covers the western Pacific, it is found that the seasonal variation of the NBL can be well reproduced as long as the

Oil plumes released from subsea blowouts can induce strong optical extinction effect and significantly affect radiative transfer in the ocean euphotic zone where photosynthesis occurs. In this paper, the effect of oil plumes on the ocean radiative transfer is studied numerically by modeling the dispersion of oil plume in the ocean mixed layer and the radiative transfer through the oil-contaminated

We present a creek-to-ocean 3D baroclinic model based on unstructured grids that aims to unite traditional hydrologic and ocean models in a single modeling platform, by taking full advantage of the polymorphism (i.e. a single model grid can seamlessly morph between full 3D, 2DV, 2DH and quasi-1D configurations). Using Hurricane Irene (2011)’s impact on the Delaware Bay as an example, a seamless 2D–3D

With regional ocean models, generating small-scale structures is important in dynamical downscaling using the nesting method. Numerous studies have shown that the generation of small-scale features is driven by large-scale flows and information supplied at the lateral boundaries by a global-scale model or observations, along with local forcing. This work, however, finds that the conventional downscaling

The aim of this study is to develop a Weibull-based distributed downscaling technique for wind field as forcing for the wave models to investigate the wave climate under future scenarios. For this purpose, the statistical downscaling approach modifies Weibull distribution parameters of the global circulation model wind speeds based on the corresponding features of wind data of ECMWF (European Center

This article describes 3D medium (4km) and high (500m) horizontal resolution ocean models developed for the Coral Sea with a particular focus on the Great Barrier Reef lagoon. The medium resolution model is underpinning a 10 year reanalysis and a forecast demonstrator system for maritime monitoring. The ocean models have been developed to assist the management of the Great Barrier Reef given the existence

We downscaled a free ensemble of a regional, parent model to a high-resolution coastal, child ensemble in the Bay of Biscay. The child ensemble was forced at the open boundaries by the parent ensemble, and locally by perturbing the winds. By comparing ensembles generated by each of these forcing perturbations separately and combined we were able to consider the ensemble from either of two paradigms:

This study investigates the design of unstructured mesh resolution and its impact on the modeling of barotropic tides along the United States East Coast and Gulf Coast (ECGC). A discrete representation of a computational ocean domain (mesh design) is necessary due to finite computational resources and an incomplete knowledge of the physical system (e.g., shoreline and seabed topography). The selection

A coupled ice-ocean model with a horizontal resolution of 7 km is developed for the Newfoundland and Labrador Shelves to examine climate trend and variability of ocean and ice conditions over 1979–2010. Daily surface atmospheric forcing is applied and monthly open boundary conditions are prescribed. The model has reasonable skill in simulating interannual and decadal variability and long-term (1979–2010)

We present an analysis of annual and seasonal mean characteristics of the Indian Ocean circulation and water masses from 16 global ocean–sea-ice model simulations that follow the Coordinated Ocean-ice Reference Experiments (CORE) interannual protocol (CORE-II). All simulations show a similar large-scale tropical current system, but with differences in the Equatorial Undercurrent. Most CORE-II models

Averaging techniques are used to generate upscaled forms of the shallow water equations for storm surge including subgrid corrections. These systems are structurally similar to the standard shallow water equations but have additional terms related to integral properties of the fine-scale bathymetry, topography, and flow. As the system only operates with coarse-scale variables (such as averaged fluid

The ocean state off Oregon-Washington, U.S. West coast, is highly variable in time. Under these conditions the assumption made in traditional 4-dimensional variational data assimilation (4DVAR) that the prior model (background) error covariance is the same in every data assimilation (DA) window can be limiting. A DA system based on an ensemble of 4DVARs (En4DVar) has been developed in which the background

This article describes a 10 year regional ocean reanalysis of the western Coral Sea and Great Barrier Reef (GBR) from 2006–2015. Here we use the Regional Ocean Modelling System (ROMS) at 4 km resolution and EnOI (Ensemble Optimal Interpolation) data assimilation. We also account for river freshwater discharge at the coast using hydrological stream gauge observations. The system appears to constrain

This paper presents two semi-implicit nonhydrostatic models to simulate surface water waves. Both models utilize the pressure correction method to solve three-dimensional (3D) incompressible Navier–Stokes equations (NSEs), but one is a noniterative model and the other is associated with iterating to solve the Poisson equation for pressure correction terms. To meet the high computational demands, the

Numerical modeling shows great potential as a method for investigating and predicting the future development of ice shelves in a warming climate. The quality of ice shelf-ocean models is continuously improving but some limitations remain. For models using a terrain-following vertical coordinate, one such limitation is the enforcement of a minimum water-column thickness beneath ice shelves by adjustment

Research performed to-date on data assimilation (DA) in storm surge modeling has found it to have limited value for predicting rapid surge responses (e.g., those accompanying tropical cyclones). In this paper, we submit that a well-resolved, barotropic hydrodynamic model is typically able to capture the surge event itself, leaving slower processes that determine the large scale, background water level

In this study we investigated the capabilities of the mesh-free, Lagrangian particle method (Smoothed Particle Hydrodynamics, SPH) to simulate the detailed hydrodynamic processes generated by both spilling and plunging breaking waves within the surf zone. The weakly-compressible SPH code DualSPHysics was applied to simulate wave breaking over two distinct bathymetric profiles (a plane beach and fringing

Storm propagation speed (SPS) can noticeably impact coastal floods around semi-closed basins influenced by extratropical offshore storms. As a case study, the SPS impact on potential flood hazards due to extreme water levels along the UK east coast was studied using a numerical shelf sea model (FVCOM). The storm Xaver, which caused the largest North Sea surge over the past 60 years, was studied as

A high-resolution ocean circulation model for the Indian Ocean (IO) using Regional Ocean Modeling System (ROMS) is operational at Indian National Centre for Ocean Information Services (INCOIS) which provides ocean state forecasts for the Bay of Bengal (BoB) and the Arabian Sea (AS) to the Indian Ocean rim countries. To provide an improved estimate of ocean state, a variant of Ensemble Kalman Filter

To resolve nonlinear internal wave motions in regional domains, we propose a one-way ocean model nesting framework in which a nonhydrostatic model is nested within a regional model. The nesting scheme produces internal tides that propagate freely into and out of the nonhydrostatic model domain with no reflections while nudging the low-frequency motions. We demonstrate the method with idealized test

This paper summarizes the findings of a workshop convened in the United States in 2018 to discuss methods in coastal and estuarine modeling and to propose key areas of research and development needed to improve their accuracy and reliability. The focus of this paper is on physical processes, and we provide an overview of the current state-of-the-art based on presentations and discussions at the meeting

In this study, we examined the possible impacts of atmospheric model resolution and physics on simulating two types of El Niño events. Four experiments were conducted using two different versions of the Community Atmosphere Model (i.e., CAM4 and CAM5) at two different resolutions. Compared with the CAM4 experiments, the CAM5 experiments yielded longer periods for both types of El Niño events, while

Despite the recent success achieved by the unstructured-grid SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model) in multi-resolution studies, its skill in simulating the baroclinic eddying ocean needs to be further improved. In particular, the classical 2nd-order transport schemes for estuaries and coastal zones are too dissipative to resolve the baroclinic dynamics associated with

We develop asymptotic expressions for wave action density and action flux, using an extension of Kirby & Chen (1989)’s perturbation solution for weakly-sheared currents allowing for a basic flow with Froude number F=U∕gh=O(1) but with weak vertical shear. The accuracy of the expressions for action density and flux is established by comparison to analytic results for a current with constant shear, and

The problem of augmenting low-resolution ocean circulation models with the information extracted from the data relevant to the unresolved subgrid processes is addressed. A highly nonlinear model of eddy-resolving oceanic circulation – quasigeostrophic wind-driven double gyres – is considered. The model solutions are characterized by a vigorous dynamic coupling between the resolved large-scale and small-scale

El Niño-Southern Oscillation (ENSO) is recognized as one of the potentially predictable drivers of California Current System (CCS) variability. In this study, we analyze a 67-year coarse-resolution (∼1°) simulation using the ocean model CESM-POP2-BEC forced by NCEP/NCAR reanalysis winds to develop a model composite of the physical–biological response of the CCS during ENSO events. The model results