Effects of Wave-Induced Processes in a Coupled Wave–Ocean Model on Particle Transport Simulations

This study investigates the effects of wind–wave processes in a coupled wave–ocean circulation model on Lagrangian transport simulations. Drifters deployed in the southern North Sea from May to June 2015 are used. The Eulerian currents are obtained by simulation from the coupled circulation model (NEMO) and the wave model (WAM), as well as a stand-alone NEMO circulation model. The wave–current interaction processes are the momentum and energy sea state dependent fluxes, wave-induced mixing and Stokes–Coriolis forcing. The Lagrangian transport model sensitivity to these wave-induced processes in NEMO is quantified using a particle drift model. Wind waves act as a reservoir for energy and momentum. In the coupled wave–ocean circulation model, the momentum that is transferred into the ocean model is considered as a fraction of the total flux that goes directly to the currents plus the momentum lost from wave dissipation. Additional sensitivity studies are performed to assess the potential contribution of windage on the Lagrangian model performance. Wave-induced drift is found to significantly affect the particle transport in the upper ocean. The skill of particle transport simulations depends on wave–ocean circulation interaction processes. The model simulations were assessed using drifter and high-frequency (HF) radar observations. The analysis of the model reveals that Eulerian currents produced by introducing wave-induced parameterization into the ocean model are essential for improving particle transport simulations. The results show that coupled wave–circulation models may improve transport simulations of marine litter, oil spills, larval drift or transport of biological materials.

Download Full-text

Multi-grid algorithm for passive tracer transport in the NEMO ocean circulation model: a case study with the NEMO OGCM (version 3.6)

Geoscientific Model Development ◽

10.5194/gmd-13-5465-2020 ◽

2020 ◽

Vol 13 (11) ◽

pp. 5465-5483

Author(s):

Clément Bricaud ◽

Julien Le Sommer ◽

Gurvan Madec ◽

Christophe Calone ◽

Julie Deshayes ◽

...

Keyword(s):

Spatial Resolution ◽

Ocean Circulation ◽

Circulation Model ◽

Ocean Model ◽

Ocean Dynamics ◽

Global Ocean ◽

Passive Tracer ◽

Tracer Transport ◽

Ocean Circulation Model ◽

Grid Algorithm

Abstract. Ocean biogeochemical models are key tools for both scientific and operational applications. Nevertheless the cost of these models is often expensive because of the large number of biogeochemical tracers. This has motivated the development of multi-grid approaches where ocean dynamics and tracer transport are computed on grids of different spatial resolution. However, existing multi-grid approaches to tracer transport in ocean modelling do not allow the computation of ocean dynamics and tracer transport simultaneously. This paper describes a new multi-grid approach developed for accelerating the computation of passive tracer transport in the Nucleus for European Modelling of the Ocean (NEMO) ocean circulation model. In practice, passive tracer transport is computed at runtime on a grid with coarser spatial resolution than the hydrodynamics, which reduces the CPU cost of computing the evolution of tracers. We describe the multi-grid algorithm, its practical implementation in the NEMO ocean model, and discuss its performance on the basis of a series of sensitivity experiments with global ocean model configurations. Our experiments confirm that the spatial resolution of hydrodynamical fields can be coarsened by a factor of 3 in both horizontal directions without significantly affecting the resolved passive tracer fields. Overall, the proposed algorithm yields a reduction by a factor of 7 of the overhead associated with running a full biogeochemical model like PISCES (with 24 passive tracers). Propositions for further reducing this cost without affecting the resolved solution are discussed.

Download Full-text

Changes in Ocean Heat Content Caused by Wave-Induced Mixing in a High-Resolution Ocean Model

Journal of Physical Oceanography ◽

10.1175/jpo-d-17-0142.1 ◽

2018 ◽

Vol 48 (5) ◽

pp. 1139-1150 ◽

Cited By ~ 5

Author(s):

Lachlan Stoney ◽

Kevin J. E. Walsh ◽

Steven Thomas ◽

Paul Spence ◽

Alexander V. Babanin

Keyword(s):

High Resolution ◽

Ocean Circulation ◽

Heat Content ◽

Circulation Model ◽

Additional Term ◽

Ocean Model ◽

Ocean Heat Content ◽

Sea Surface ◽

Wave Heights ◽

Wave Induced

Abstract A parameterization of turbulent mixing from unbroken surface waves is included in a 16-yr simulation within a high-resolution ocean circulation model (MOM5). This “surface wave mixing” (SWM) derives from the wave orbital motion and is parameterized as an additional term in a k-epsilon model. We show that SWM leads to significant changes in sea surface temperatures but smaller changes in ocean heat content, and show the extent to which these changes can reduce pre-existing model biases with respect to observed data. Specifically, SWM leads to a widespread improvement in sea surface temperature in both hemispheres in summer and winter, while for ocean heat content the improvements are less clear. In addition, we show that introducing SWM can lead to an accumulation of wave-induced ocean heat content between years. While it has been well established that secular positive trends exist in global wave heights, we find that such trends are relatively unimportant in driving the accumulation of wave-induced ocean heat content. Rather, in response to the new source of mixing, the simulated ocean climate evolves toward a new equilibrium with greater total ocean heat content.

Download Full-text

Multi-grid algorithm for passive tracer transport in NEMO ocean circulation model: a case study with NEMO OGCM (version 3.6)

10.5194/gmd-2019-341 ◽

2020 ◽

Cited By ~ 1

Author(s):

Clément Bricaud ◽

Julien Le Sommer ◽

Madec Gurvan ◽

Christophe Calone ◽

Julie Deshayes ◽

...

Keyword(s):

Spatial Resolution ◽

Ocean Circulation ◽

Circulation Model ◽

Ocean Model ◽

Ocean Dynamics ◽

Global Ocean ◽

Passive Tracer ◽

Tracer Transport ◽

Ocean Circulation Model ◽

Grid Algorithm

Abstract. Ocean biogeochemical models are key tools for both scientific and operational applications. Nevertheless the cost of running these models is often expensive because of the large number of biogeochemical tracers. This has motivated the development of multi-grid approaches where ocean dynamics and tracer transport are computed on grids of different spatial resolution. However, existing multi-grid approaches to tracer transport in ocean modelling do not allow to compute ocean dynamics and tracer transport simultaneously. This paper describes a new multi-grid approach developed for accelerating the computation of passive tracer transport in the NEMO ocean circulation model. In practice, passive tracer transport is computed at runtime on a grid with coarser spatial resolution than the hydrodynamics, which allows to reduce the CPU cost of computing the evolution of tracer. We describe the multi-grid algorithm, its practical implementation in the NEMO ocean model, and discuss its performance on the basis of a series of sensitivity experiments with global ocean model configurations. Our experiments confirm that the spatial resolution of hydrodynamical fields can be coarsened by a factor 3 in both horizontal directions without significantly affecting the resolved passive tracer fields. Overall, the proposed algorithm yields a reduction by a factor 7 of the overhead associated with running a full biogeochemical model like PISCES (with 24 passive tracers). Propositions for reducing further this cost without affecting the resolved solution are discussed.

Download Full-text

Wave-induced mixing in the upper ocean: Distribution and application to a global ocean circulation model

Geophysical Research Letters ◽

10.1029/2004gl019824 ◽

2004 ◽

Vol 31 (11) ◽

pp. n/a-n/a ◽

Cited By ~ 191

Author(s):

Fangli Qiao ◽

Yeli Yuan ◽

Yongzeng Yang ◽

Quanan Zheng ◽

Changshui Xia ◽

...

Keyword(s):

Ocean Circulation ◽

Circulation Model ◽

Global Ocean ◽

Upper Ocean ◽

Ocean Circulation Model ◽

Global Ocean Circulation ◽

Wave Induced

Download Full-text

Estimating Eddy Stresses by Fitting Dynamics to Observations Using a Residual-Mean Ocean Circulation Model and Its Adjoint

Journal of Physical Oceanography ◽

10.1175/jpo2785.1 ◽

2005 ◽

Vol 35 (10) ◽

pp. 1891-1910 ◽

Cited By ~ 118

Author(s):

David Ferreira ◽

John Marshall ◽

Patrick Heimbach

Keyword(s):

Ocean Circulation ◽

Large Scale ◽

Three Dimensional ◽

Circulation Model ◽

Eddy Diffusivity ◽

Ocean Model ◽

Global Ocean ◽

Western Boundary ◽

Mean Flow ◽

Ocean Circulation Model

Abstract A global ocean circulation model is formulated in terms of the “residual mean” and used to study eddy–mean flow interaction. Adjoint techniques are used to compute the three-dimensional eddy stress field that minimizes the departure of the coarse-resolution model from climatological observations of temperature. The resulting 3D maps of eddy stress and residual-mean circulation yield a wealth of information about the role of eddies in large-scale ocean circulation. In eddy-rich regions such as the Southern Ocean, the Kuroshio, and the Gulf Stream, eddy stresses have an amplitude comparable to the wind stress, of order 0.2 N m−2, and carry momentum from the surface down to the bottom, where they are balanced by mountain form drag. From the optimized eddy stress, 3D maps of horizontal eddy diffusivity κ are inferred. The diffusivities have a well-defined large-scale structure whose prominent features are 1) large values of κ (up to 4000 m2 s−1) in the western boundary currents and on the equatorial flank of the Antarctic Circumpolar Current and 2) a surface intensification of κ, suggestive of a dependence on the stratification N 2. It is shown that implementation of an eddy parameterization scheme in which the eddy diffusivity has an N 2 dependence significantly improves the climatology of the ocean model state relative to that obtained using a spatially uniform diffusivity.

Download Full-text

MOMSO 1.0 - a near-global, coupled biogeochemical ocean-circulation model configuration with realistic eddy kinetic energy in the Southern Ocean

10.5194/gmd-2018-297 ◽

2019 ◽

Author(s):

Heiner Dietze ◽

Ulrike Löptien ◽

Julia Getzlaff

Keyword(s):

Kinetic Energy ◽

Southern Ocean ◽

Ocean Circulation ◽

Computational Cost ◽

Circulation Model ◽

Ocean Model ◽

Eddy Kinetic Energy ◽

Ocean Circulation Model ◽

Model Configuration ◽

Modular Ocean Model

Abstract. We present a new near-global coupled biogeochemical ocean-circulation model configuration. The configuration features a horizontal discretization with a grid spacing of less than 11 km in the Southern Ocean and gradually coarsens in meridional direction to more than 200 km at 64° N where the model is bounded by a solid wall. The underlying code framework is GFDL's Modular Ocean Model coupled to the Biology Light Iron Nutrients and Gasses (BLING) ecosystem model of Galbraith et al. (2010). The configuration is cutting-edge in that it features both a relatively equilibrated oceanic carbon inventory and a realistic representation of eddy kinetic energy – a combination that has, to-date, been precluded by prohibitive computational cost. Results from a simulation with climatological forcing and a sensitivity experiment with increasing winds suggest that the configuration is suited to explore Southern Ocean Carbon uptake dynamics on decadal timescales. Further, the fidelity of simulated bottom water temperatures off and on the Antarctic Shelf suggest that the configuration may be used to provide boundary conditions to ice-sheet models. The configuration is dubbed MOMSO a Modular Ocean Model Southern Ocean configuration.

Download Full-text

Tracking the long-distance dispersal of marine organisms: sensitivity to ocean model resolution

Journal of The Royal Society Interface ◽

10.1098/rsif.2012.0979 ◽

2013 ◽

Vol 10 (81) ◽

pp. 20120979 ◽

Cited By ~ 75

Author(s):

Nathan F. Putman ◽

Ruoying He

Keyword(s):

Ocean Circulation ◽

Circulation Model ◽

Ocean Model ◽

Marine Organisms ◽

Model Output ◽

Ocean Circulation Model ◽

Time Step ◽

Long Distance ◽

Near Surface ◽

Basin Scale

Ocean circulation models are widely used to simulate organism transport in the open sea, where challenges of directly tracking organisms across vast spatial and temporal scales are daunting. Many recent studies tout the use of ‘high-resolution’ models, which are forced with atmospheric data on the scale of several hours and integrated with a time step of several minutes or seconds. However, in many cases, the model's outputs that are used to simulate organism movement have been averaged to considerably coarser resolutions (e.g. monthly mean velocity fields). To examine the sensitivity of tracking results to ocean circulation model output resolution, we took the native model output of one of the most sophisticated ocean circulation models available, the Global Hybrid Coordinate Ocean Model, and averaged it to commonly implemented spatial and temporal resolutions in studies of basin-scale dispersal. Comparisons between simulated particle trajectories and in situ near-surface drifter trajectories indicated that ‘over averaging’ model output yields predictions inconsistent with observations. Further analyses focused on the dispersal of juvenile sea turtles indicate that very different inferences regarding the pelagic ecology of these animals are obtained depending on the resolution of model output. We conclude that physical processes occurring at the scale of days and tens of kilometres should be preserved in ocean circulation model output to realistically depict the movement marine organisms and the resulting ecological and evolutionary processes.

Download Full-text